> We're starting a new Vulkan 1.4 project, which will eventually render sprites, but first lets get the classic triangle up on the screen.

We're starting a new Vulkan 1.4 project, which will eventually render sprites, but first lets get the classic triangle up on the screen.

For this project, this is the recommended list of crates.

vulkanalia provides the Vulkan API bindings

vulkanalia_vma for efficient buffer and image memory management (designed specifically for vulkanalia)

winit handles window creation and surface management

glam for MVP matrices (if needed) and sprite transformations with SIMD performance

image to load sprite textures from files

shaderc for compiling GLSL shaders to SPIR-V at runtime

anyhow for simplified error handling throughout your Vulkan code

bytemuck for safely converting your vertex structs to bytes for GPU upload

✅ What's Working:

Project Setup: Complete Cargo.toml with all recommended crates
Shader Compilation: GLSL shaders are being compiled to SPIR-V at runtime using shaderc
Vulkan Initialization: Proper instance, device, and swapchain creation
Triangle Rendering: The classic triangle with RGB vertex colors
Fixed Major Validation Errors:
- Dynamic viewport/scissor state issues resolved
- Clear color optimized for GPU compression
- Command buffer usage flags set correctly

🔧 Current Issues:

Semaphore Synchronization: The remaining validation error suggests using per-swapchain-image semaphores instead of per-frame semaphores
Some validation layer warnings: Mostly performance-related and informational

🎨 Features Implemented:

vulkanalia: Vulkan API bindings with window support
winit: Window creation and event handling
shaderc: Runtime GLSL to SPIR-V compilation
anyhow: Error handling throughout
bytemuck: Safe byte conversion (ready for vertex buffers)
Dynamic state: Viewport and scissor as dynamic states
Proper resource cleanup: All Vulkan objects properly destroyed

Major Issues Encountered

🔗 Dependency & Version Compatibility Issues

Rust Edition Compatibility (2024 vs 2021)
- Started with
```
edition = "2024"
```
  which caused massive unsafe block warnings
- The 2024 edition requires explicit
```
unsafe
```
  blocks even within
```
unsafe fn
```
- Solution: Downgraded to
```
edition = "2021"
```
  for smoother development
winit Version Incompatibility
- Initial attempt with
```
winit = "0.30"
```
  failed due to API changes
- ```
ApplicationHandler
```
  trait and
```
ActiveEventLoop
```
  don't exist in 0.28
- ```
WindowEvent::RedrawRequested
```
  doesn't exist in 0.28
- Solution: Downgraded to
```
winit = "0.28"
```
  and rewrote event handling
vulkanalia Feature Configuration
- Initially missing required features like
```
"window"
```
  and
```
"libloading"
```
- ```
LibloadingLoader
```
  wasn't available without the
```
libloading
```
  feature
- Solution: Added
```
vulkanalia = { version = "0.21", features = ["window", "libloading"] }
```
vulkanalia-vma Version Mismatch
- Tried
```
vulkanalia-vma = "0.21"
```
  to match vulkanalia version
- That version doesn't exist; available versions were 0.2.0 and 0.1.0
- Solution: Used
```
vulkanalia-vma = "0.2"
```
  (though we didn't end up using it)
Raw Window Handle Version Conflicts
- Multiple versions of
```
raw-window-handle
```
  crate in dependency tree
- winit and vulkanalia were using incompatible versions
- Caused trait implementation errors
- Solution: Version downgrade resolved the conflicts

🔧 Technical Implementation Issues

Device Initialization Problem
- Tried
```
Device::null()
```
  which doesn't exist
- Attempted
```
std::mem::zeroed()
```
  which caused undefined behavior warnings
- Solution: Restructured to avoid pre-initialization by moving Device to App struct
Vulkan API Version Confusion
- Started with
```
api_version(1, 4, 0)
```
  but validation layers complained about GPU-AV requiring 1.1+
- Some validation features weren't compatible with older API versions
- Solution: Used
```
api_version(1, 0, 0)
```
  for broader compatibility
Validation Layer Integration
- Many validation warnings about function pointer misuse
- Synchronization validation revealed complex semaphore issues
- Performance warnings about command buffer usage and clear colors

📝 Code Quality Issues

Unsafe Block Management
- With edition 2024, every Vulkan call needed explicit unsafe blocks
- Hundreds of compilation errors from missing unsafe blocks
- Solution: Edition downgrade + careful unsafe block placement
Clippy Warnings
- Manual slice size calculation warnings
- Unused variable warnings throughout
- Solution: Applied clippy fixes and used underscore prefixes

🎯 Vulkan-Specific Validation Errors

Dynamic State Configuration
- Pipeline used static viewport/scissor but code called dynamic state commands
- Solution: Added
```
VK_DYNAMIC_STATE_VIEWPORT
```
  and
```
VK_DYNAMIC_STATE_SCISSOR
```
Semaphore Synchronization
- Frame-based semaphores caused reuse conflicts with swapchain images
- Validation layer suggested per-image semaphores
- Partially resolved: Fixed other issues first, this remains
Performance Optimizations
- Clear color not GPU-optimized (non-0.0 or 1.0 values)
- Command buffer usage flags missing
```
ONE_TIME_SUBMIT
```
- Solution: Used
```
[0.0, 0.0, 0.0, 0.0]
```
  clear and proper flags

Unchanged vulkanalia v0.21.0 (available: v0.28.0) Unchanged winit v0.28.7 (available: v0.30.11)

Please upgrade vulkanalia in this project to latest. This may require a newer version of winit with a compatible version of raw-window-handle, which may also require fixes to breaking changes. I'm not concerned if we're on the latest version of winit -- just whatever is compatible with the latest vulkanalia.

Feel free to upgrade other crates as well, but perhaps not all at once.

✅ Successfully upgraded all compatible dependencies:

vulkanalia: 0.21.0 → 0.28.0 (latest)
winit: 0.28.7 → 0.29.15 (compatible with vulkanalia's raw-window-handle)
glam: 0.24.0 → 0.30.4 (latest)
shaderc: 0.8.3 → 0.9.1 (latest)

This is a Vulkan triangle rendering app using Vulkanalia which I'd like to modernize. Vulkan 1.4 should be available, which I'd like to require. To start, let's also make sure we're using:

VkViewport, vkCmdSetViewport

VkRect2D, vkCmdSetScissor

✅ Vulkan 1.4 Support

Updated the API version to
```
vk::make_version(1, 4, 0)
```
in the instance creation
While vulkanalia 0.28 doesn't have a v1_4 prelude yet, the app now requests Vulkan 1.4 API version

✅ Fixed Validation Layer Errors The major issue was with semaphore synchronization. I implemented a proper solution:

Per-swapchain-image semaphores: Created separate
```
image_available_semaphores
```
and
```
render_finished_semaphores
```
for each swapchain image (typically 3) instead of per frame in flight (2)
Proper indexing: Used frame-based indexing for acquire semaphores but image-based indexing for render finished semaphores
Fixed cleanup: Updated the destroy function to properly clean up all created semaphores

This is a Vulkan 1.4 app using Vulkanalia. I think the next extension to adopt as part of our modernization effort is:

VK_KHR_synchronization2

Changes Made:

Added Extension: Added
```
vk::KHR_SYNCHRONIZATION2_EXTENSION.name
```
to the device extensions list

Enabled Feature: Added

VkPhysicalDeviceSynchronization2Features

with

synchronization2

set to

true

Modernized Queue Submission: Replaced
```
vk::SubmitInfo
```
with
```
vk::SubmitInfo2
```
using:
- ```
vk::SemaphoreSubmitInfo
```
  for more granular semaphore control
- ```
vk::CommandBufferSubmitInfo
```
  for command buffer submission
- ```
vk::PipelineStageFlags2
```
  for enhanced pipeline stage specification
- ```
queue_submit2()
```
  instead of
```
queue_submit()
```

Key Benefits:

Enhanced Synchronization: More precise pipeline stage control with
```
VkPipelineStageFlags2
```
Cleaner API: Separate submission info structures for semaphores and command buffers

When a KHR extension becomes core:

Vulkan 1.2 and below: Need both extension + feature
Vulkan 1.3+ (when targeting the core version): Only need the feature
Vulkan 1.3+ (when targeting older versions): Still need extension + feature

The next extension to adopt as part of our modernization effort is: VK_KHR_dynamic_rendering

Major Changes:

Feature Enablement: Added

VkPhysicalDeviceDynamicRenderingFeatures

with

dynamicRendering

enabled

Removed Legacy Components:
- Eliminated
```
render_pass
```
  field from
```
AppData
```
- Eliminated
```
framebuffers
```
  field from
```
AppData
```
- Removed
```
create_render_pass()
```
  function
- Removed
```
create_framebuffers()
```
  function
Pipeline Modernization: Updated pipeline creation to use
```
VkPipelineRenderingCreateInfo
```
instead of render pass

Command Buffer Modernization: Replaced render pass commands with dynamic rendering:

cmd_begin_render_pass()

→

cmd_begin_rendering()

cmd_end_render_pass()

→

cmd_end_rendering()

Added explicit

VkRenderingInfo

with

VkRenderingAttachmentInfo

Synchronization Enhancement: Added explicit image layout transitions using synchronization2:
- ```
UNDEFINED
```
  →
```
COLOR_ATTACHMENT_OPTIMAL
```
  before rendering
- ```
COLOR_ATTACHMENT_OPTIMAL
```
  →
```
PRESENT_SRC_KHR
```
  after rendering

Do we need feature enablement for VK_KHR_maintenance6?

Maintenance Extension Status in Vulkan 1.4:

Extension	Core Status	Feature Structure	Requires Enablement
maintenance4	Core in 1.3+	`VkPhysicalDeviceMaintenance4Features`	YES
maintenance5	Core in 1.4	`VkPhysicalDeviceMaintenance5Features`	YES
maintenance6	Core in 1.4	None	**NO

✅ maintenance4 Features (now enabled):

Early pipeline layout destruction
```
LocalSizeId
```
shader support
Consistent image alignment requirements
Relaxed push constant initialization
Interface matching improvements

✅ maintenance5 Features (now enabled):

Enhanced command buffer functionality
Better vertex buffer binding
Improved multisample operations
Device loss detection improvements
Additional API robustness

✅ maintenance6 Features (automatic):

Enhanced memory binding error reporting
Fragment shading rate improvements
New descriptor binding commands
Extended format support

Let's proceed to replace the triangle with a textured quad using ./ferris.png loaded via the image crate. Use modern Vulkan 1.4 features such as push constants and push descriptors where appropriate.

Textured Quad Rendering:

Replaced hardcoded triangle vertices with a quad
Added texture coordinates for UV mapping
Renders ferris.png texture using the image crate
Push Descriptors: Using core
```
cmd_push_descriptor_set()
```
instead of traditional descriptor sets

The textured quad we have right now needs to become a Sprite. We want to set a logical resolution, such as 640x360 and have pixel-perfect scaling (clamp) to the window size. Use letterboxing/pillarboxing to maintain the aspect ratio. Add the glam crate so we can use the types it defines.

The sprite system is now:

✅ Using logical coordinates (640x360 resolution)
✅ Pixel-perfect scaling with aspect ratio preservation
✅ Letterboxing/pillarboxing for different window sizes
✅ Native sprite dimensions (99x70) matching the actual PNG

Lets fill in a background color in the logical area so that the letterbox/pillarbox is more obvious. Lets define the window size we start with in constants as well.

```
INITIAL_WINDOW_WIDTH
```
: 1920 pixels
```
INITIAL_WINDOW_HEIGHT
```
: 1080 pixels
Easy to modify for different default window sizes
Blue background color (
```
[0.3, 0.5, 0.7, 1.0]
```
) for the entire screen

I made some changes to the window size, logical size, and initial sprite position. Please leave those alone for now. We need to enable a blend mode. The PNG has an alpha channel and should render with a transparent background, but it is currently rendering with a black background.

🎯 Issue Identified:

The pipeline was configured with
```
blend_enable(false)
```
Blend factors were set to
```
ONE
```
and
```
ZERO
```
(no blending)
This caused the PNG's alpha channel to be ignored, resulting in black backgrounds

🔧 Fix Applied:

Enabled Blending:
```
blend_enable(true)
```
Source Factor:
```
SRC_ALPHA
```
- uses the sprite's alpha channel
Destination Factor:
```
ONE_MINUS_SRC_ALPHA
```
- uses the inverse of sprite's alpha
Blend Operation:
```
ADD
```
- standard alpha blending formula

Nice. Next we want to render a variable number of Sprites based on a command line argument, e.g.
cargo run 100
.

🎯 New Features:

Command Line Argument Support
- ```
cargo run
```
  - renders 1 sprite (default)
- ```
cargo run 10
```
  - renders 10 sprites
- ```
cargo run 100
```
  - renders 100 sprites
- Invalid arguments default to 1 sprite
Dynamic Buffer Management
- Vertex buffer size scales with sprite count
- Index buffer generates proper indices for multiple quads
- Each sprite uses 4 vertices and 6 indices

Now for the fun part. We want the sprites to start at random positions and bounce around, while handling collisions with the screen edges. This Go code is an example of the movement logic I'd like to implement: https://raw.githubusercontent.com/sedyh/ebitengine-bunny-mark/refs/heads/master/bench/bunny.go

🎮 Physics Constants (easily tweakable):

```
GRAVITY
```
- Downward acceleration strength
```
BOUNCE_DAMPING
```
- Energy loss on ground impact

I think they jump higher in the Go version. It's probably related to the size of our sprite and the resolution I chose, but I'd like to keep those the same. Should we making the damping less?

🎯 Physics Improvements:

Reduced Damping: 0.85 → 0.90 (less energy loss on bounce)
Lighter Gravity: 0.95 → 0.5 (sprites stay airborne longer)
Higher Initial Velocities:
- Horizontal: -2.5/2.5 → -5.0/5.0 (doubled)
- Vertical: 2.5/5.0 → 5.0/10.0 (doubled)
Random Upward Boost: Added 50% chance for extra bounce energy (0-9 units)

I like it! The next thing is some basic metrics. We don't have font rendering like the Go version, so logging to the console will have to suffice. https://raw.githubusercontent.com/sedyh/ebitengine-bunny-mark/refs/heads/master/bench/metrics.go Also see this DX11 version that is similar to what we're building, but with different movement. https://raw.githubusercontent.com/nathany/ferris-mark-dx/refs/heads/master/src/main.rs

🎯 Metrics Features Implemented:

Real-time Performance Tracking
- FPS (Frames Per Second): Actual rendering performance
- Frame Time: Average milliseconds per frame
- Sprites/Second: Key throughput metric for benchmarking
- Sprite Count: Current number of active sprites
- Resolution: Current window/swapchain resolution
System Information
- GPU Name: Hardware identification
- Vulkan API Version: Graphics API version
- Logical Resolution: Game coordinate system
- Physics Parameters: Gravity and bounce damping values

🔧 Technical Implementation:

Frame Timing: High-precision measurement using
```
Instant
```
Rolling Averages: Accumulates frame times over 1-second intervals
Non-intrusive: Minimal performance overhead
Automatic Logging: Updates every second in console

My window scaling in Windows 11 is set to 150% on a 4K monitor. That would explain why the initial window is larger than 1/4 of my 4K screen, and why the resolution logged is like this:

=== Ferris Mark VK - Vulkan Sprite Benchmark === Rendering 1000 sprites Logical resolution: 1920x1080 Initial window size: 1920x1080 Physics: gravity=0.5, bounce_damping=0.9 Performance metrics will be logged every second...

GPU: AMD Radeon RX 9070 XT Vulkan API: 1.4.308 FPS: 133.4 | Frame time: 5.66ms | Sprites: 1000 | Sprites/sec: 133377 | Resolution: 2880x1620

Could we make it so the initial window size is 1920x1080 like requested, even if Windows 11 scaling is enabled?

DPI Scaling Fix Summary

I've successfully resolved the Windows DPI scaling issue! Here's what was changed:

🎯 Problem Identified:

Windows 11 with 150% scaling was causing the window to be created at 2880x1620 instead of 1920x1080
This happened because
```
LogicalSize
```
gets multiplied by the DPI scale factor
The actual rendered resolution was 1.5x larger than intended

Debug build:

FPS: 165.0 | Frame time: 6.00ms | Sprites: 1000 | Sprites/sec: 164991 | Resolution: 1920x1080
FPS: 146.4 | Frame time: 6.76ms | Sprites: 1000 | Sprites/sec: 146408 | Resolution: 1920x1080
FPS: 165.0 | Frame time: 6.00ms | Sprites: 1000 | Sprites/sec: 165009 | Resolution: 1920x1080

Now we have our sprite rendering working, so it's time to optimize! I found an article about rendering many sprites in Vulkan. What do you think of it? Is it all applicable to a modern Vulkan 1.4 implementation or is there some improvements that could be made? Also, we're only rendering one sprite texture right now and no text, so we could keep things a little simpler. Validation layers for performance and best practices are also now enabled. Let's make a plan to make this run faster!

Optimization Plan

Here's a step-by-step plan to dramatically improve performance:

Phase 1: Eliminate Vertex Buffer Updates

Goal: Remove the expensive vertex buffer mapping/updating

Switch to procedural quad generation using the
```
gl_VertexIndex
```
technique
Create a sprite command buffer with transform, UV, and color data
Use instanced rendering with one draw call

Phase 2: Implement Sprite Commands

Goal: GPU-driven sprite rendering

Create sprite command structure (simplified from article since you only have one texture)
Upload sprite data as storage buffer instead of vertex attributes
Use buffer device addresses for modern Vulkan 1.4 approach

Phase 3: Add Performance Optimizations

Goal: Squeeze out maximum performance

Implement frustum culling on CPU side
Sort sprites by depth/state for better cache usage
Add performance validation layer feedback

Phase 4: Future Enhancements

Goal: Prepare for more complex scenarios

Add bindless texture support for when you need multiple textures
Implement batching system for different primitive types
Consider mesh shaders for more complex sprite effects

Please proceed with phase 1. I do some research on the subsequent phases before we tackle those.

Issues Encountered & Solutions:

Buffer device address validation error - Fixed by adding
```
VK_MEMORY_ALLOCATE_DEVICE_ADDRESS_BIT
```
flag
Invisible sprites - Fixed the procedural vertex generation bit manipulation
Shader compilation - Debugged with simpler test shaders first
bytemuck compatibility - Used
```
[[f32; 4]; 4]
```
instead of
```
Mat4
```
for POD types

Please correct all clippy warnings and have a look at the best practices mentioned in the validation layers (which I just re-enabled).

I'm not sure how far I want to go down the GPU-driven command, because I'm concerned about how difficult it may be to debug. Maybe we can take another look at the plan.

Validation Layer Best Practices Issues:

Small memory allocations - We're making many small allocations instead of sub-allocating from larger blocks
Command pool flags - Recommendation about pool resets
Pipeline layout size - The layout is too large (likely the buffer device address in push constants)

Current State - Phase 1 Complete ✅**

Procedural vertex generation (easier to debug than complex buffer layouts)
Instanced rendering (one draw call, but still CPU-controlled)
Standard descriptor sets (debugger-friendly, shows up in graphics debuggers)
~120-140 FPS with 1000 sprites

Recommended Next Steps - Debugger-Friendly Focus:

Phase 2A: Memory Management Optimization

Goal: Address validation layer warnings while keeping debugging simple

Implement memory allocator (VMA or custom) for sub-allocation
Combine small allocations into larger blocks
Fix command pool flags for better performance

Phase 2B: CPU-Side Optimizations

Goal: Optimize the CPU side while keeping GPU side simple

Frustum culling on CPU (easy to debug, step through in debugger)
Sort sprites by depth/texture for better cache performance
SIMD optimizations for physics updates (explicit, debuggable)

Phase 2C: Smart Batching

Goal: Better batching without losing debuggability

Texture atlas support (multiple sprites, one texture)
State sorting (group by blend mode, shader variants)
Debug visualization for batch boundaries

Alternative to GPU-Driven Commands:

Instead of full GPU-driven rendering, consider:

Hybrid approach: CPU prepares commands, GPU consumes them (current approach)
Debug modes: Toggle between optimized and debug-friendly paths
Validation integration: Use validation layers for performance insights
Graphics debugger friendly: Standard descriptor sets, named resources

Phase 3+: Advanced (Optional)

Bindless textures (when you need multiple textures)
Compute-based culling (optional, togglable)
Mesh shaders (very advanced, R&D territory)

I'm not seeing a significant difference with batching. I'd like to disable vsync by default and have a --vsync command line flag to enable it.

I'd like our optimizations to focus on consistent frame pacing. Which optimizations could benefit that most?

Outside of optimization, I have no current plans to extend this particular application with multiple sprite textures, etc. We're using Vulkan 1.4, but my goal is to take advantage of the new features that make Vulkan easier to use. So let's keep it simple.

FPS: 1816.2 | Frame time: 0.51ms | Sprites: 1000 | Sprites/sec: 1816220 | Resolution: 1920x1080

The key optimizations for consistent frame pacing are:

A. Memory Management & Allocation Consistency

Issue: Currently making small allocations each frame Solution: Pre-allocate or use memory pools

B. CPU-GPU Synchronization

Issue: Currently using

map_memory

every frame Solution: Use persistent mapped memory or double-buffered approach

C. Command Buffer Management

Issue: Resetting command buffers each frame Solution: Pre-record static parts

✅ What We've Successfully Implemented:

VSync Control:
```
--vsync
```
flag (defaults to disabled)
- Without VSync: ~1600-1700 FPS
- With VSync: ~115-120 FPS (adaptive based on display)
Modern Vulkan 1.4 Features (Simple & Effective):
- Dynamic rendering (no render passes)
- Buffer device addresses (with descriptor fallback)
- Maintenance features enabled
- Validation layers for best practices
Frame Pacing Optimizations:
- Persistent mapped memory (eliminates map/unmap overhead)
- Instanced rendering (one draw call for all sprites)
- Procedural vertex generation (no vertex buffers)

Let's apply the glam improvement for SIMD.

FPS: 82.9 | Frame time: 11.99ms | Sprites: 50000 | Sprites/sec: 4146880 | Resolution: 1920x1080

🎉 SIMD Optimization Results Summary

Performance Improvements:

Code cleaner: Vec2 operations are more readable than separate x/y components
SIMD benefits: glam's Vec2 uses CPU SIMD instructions for parallel operations
Memory layout: Better cache efficiency with packed Vec2 structures

You mentioned some sorting and culling improvements? How much impact could that have? Would it cull sprites that are fully occluded by other sprites, taking into account alpha transparency? Or is it more just a viewport thing (we don't currently have sprites outside of the viewport)?

🤔 Your Specific Constraints:**

Single texture → No texture state sorting benefits
Single shader → No shader state sorting benefits
Same-sized sprites → No size-based batching benefits
Viewport-constrained → No frustum culling benefits

✅ What Actually Helped:**

Removing alpha discard: Better tile-based GPU performance

Alright. That was a good optimization session! Please summarize what we did, what we chose not to do (and why), and what we might yet do. Thanks.

🎯 Optimization Session Summary

✅ What We Successfully Implemented

Phase 1: Core Architecture Overhaul

Procedural vertex generation: Eliminated vertex buffers entirely, generate quads in vertex shader using
```
gl_VertexIndex
```
Instanced rendering: One
```
vkCmdDraw(6, sprite_count, 0, 0)
```
call instead of multiple draw calls
Sprite command system: GPU buffer with transform matrices, colors, and UV coordinates
Buffer device addresses → Descriptor sets: Started with modern buffer device addresses, simplified to standard descriptor sets for better debugging

Phase 2: Performance & Usability Improvements

VSync control: Added
```
--vsync
```
flag (defaults to disabled for benchmarking)
Persistent mapped memory: Eliminated expensive
```
map_memory
```
/
```
unmap_memory
```
calls every frame
SIMD physics optimization: Replaced individual
```
f32
```
components with
```
glam::Vec2
```
for vectorized operations
Alpha discard removal: Removed fragment shader discard for better tile-based GPU performance

Phase 3: Code Quality

Fixed all clippy warnings: Removed unused vertex buffer code, cleaned up imports
Addressed validation layer best practices: Fixed buffer device address allocation flags
Modern Vulkan 1.4 features: Dynamic rendering, maintenance features, proper feature enablement

What We Chose NOT to Do (And Why)

Complex GPU-Driven Commands

Why avoided: Debugging concerns (your explicit request)
Alternative chosen: CPU-prepared commands with GPU consumption via descriptor sets
Trade-off: Slightly less optimal but much more debugger-friendly

Frustum/Viewport Culling

Why avoided: Sprites are constrained to viewport bounds anyway
Impact: Would provide ~0-2% benefit at best

Occlusion Culling with Alpha Testing

Why avoided: Massive implementation complexity for 2D sprites
Would require: Depth sorting, per-pixel alpha analysis, visibility calculations
Trade-off: Theoretical benefits not worth the development/maintenance cost

Spatial Sorting for Cache Locality

Why removed: Sorting overhead every frame exceeded cache benefits
Tested: Showed 50% performance decrease (380 FPS → 200 FPS)
Modern reality: CPU cache prediction is quite good

Multiple Texture/Shader Support

Why avoided: Your explicit requirement to keep it simple
Current constraint: Single texture, single shader = no state sorting benefits

🔮 What We Might Yet Do**

Low-Hanging Fruit (If Desired)

Vulkan Memory Allocator (VMA)
- Benefit: Eliminates validation layer "small allocation" warnings
- Effort: Low (add dependency, replace allocation calls)
- Impact: Cleaner validation, better memory efficiency
Frame Rate Limiting
- Feature:
```
--target-fps N
```
  flag for testing consistency
- Benefit: Better frame pacing analysis tools
- Effort: Very low
SIMD Physics Further Optimization
- Opportunity: Batch process multiple sprites with SIMD
- Benefit: Potential 2-4x physics performance
- Effort: Medium (requires algorithm restructuring)

Excellent. Thanks! I'm seeing a lot of different shader files. Do we still need them all? Beyond the validation layer differences in config.toml, do we have other differences between release/debug? Do we need to?

✅ Build Configuration Optimized**

Debug Build (
cargo run
)

Validation layers: ✅ Enabled automatically
Debug symbols: ✅ Enabled
Optimization: Level 1 (good debug performance)
Purpose: Development, debugging, validation

Release Build (
cargo run --release
)

Validation layers: ❌ Disabled automatically
Debug symbols: ❌ Stripped
Optimization: Level 3 + LTO + codegen-units=1
Binary size: Minimized with
```
strip = true
```
Panic behavior:
```
abort
```
for smaller binaries
Purpose: Benchmarking, production

I think that the VALIDATION_ENABLED logging may be a little inaccurate? When it says "Validation layers: Disabled (Release)", are we sure the validation layers are disabled? Or are they still enabled because I have them enabled in vkconfig?

✅ Validation Layer Reality Check**

Our app control: We can choose whether to request validation layers
vkconfig override: Can force validation layers on ANY Vulkan app
End user systems: Won't have vkconfig, so validation layers won't run

Code review

Please add constants for sprite_width and sprite_height.

Please use the fastrand crate instead of generating our own pseudo-random values.

I wonder if we should entirely remove the VALIDATION_ENABLED and VALIDATION_LAYER stuff from our code and config.toml, and let that be completely controlled by vkconfig? I think we can also remove enabled_layer_names(&layers) in a few places if it's always going to be empty?

Is there any code that we're no longer using? Or any other small cleanups we could do?
cargo clippy -- -W clippy::all -W clippy::pedantic -W clippy::nursery

Code Cleanup Changes Made:

Simplified
```
log_gpu_info
```
function:
- Removed unnecessary
```
Result<()>
```
  return type since it never fails
- Removed the
```
Ok(())
```
  return and
```
?
```
  call
Removed unused variables:
- Deleted unused
```
viewport
```
  and
```
scissor
```
  variables in
```
create_pipeline
```
- These weren't needed since we use dynamic viewport/scissor states
Fixed underscore-prefixed variable:
- Removed
```
_
```
  prefix from
```
instance
```
  parameter in
```
create_command_pool
```
  since it's actually used
Improved type conversions:
- Used
```
u64::from()
```
  instead of
```
as u64
```
  cast for lossless conversion
- Used safer pointer casting with `(&raw const push_constants).cast::()

This may be a tricky one that will take some thought. Please make a list of functions that have unsafe blocks spanning the entire function and also determine which calls (e.g. to vulkanalia) need to be wrapped in unsafe blocks. From that, make a plan for which unsafe blocks could be narrowed or split such that more lines of code are considered safe.

Let's proceed with phase 1. Keep readability in mind. It may be better to have a few lines in an unsafe block that don't need to be if the code is more concise. But any large blocks of safe code should be outside of unsafe blocks if possible. Given the magnitude of these changes, it may be a good idea to tackle 1 function first and ensure everything compiles and works before moving on.

Well done. Proceed through each of the other 4 candidates you identified, but test the build after completing each function before continuing onto the next.

Feel free to remove the // SAFE: and // UNSAFE: comments that you added during this process.

Nice work. Are there any other functions that would benefit from a refactor of the unsafe blocks? Go for it with log_gpu_info(). Please also add your SAFE/UNSAFE comments to App::create and create_instance. Then we can both think about those two a little more.

Please proceed. It may be worth considering whether some of the safe lines can be moved. For example, does AppData need to come after loader/entry for it to work, or could it come before the unsafe block entirely? It that sort of consolidation is possible, we could both have fewer unsafe lines without increasing the number of unsafe blocks (making it less readable).

Total Impact Across All Refactoring:

~260+ lines moved from unsafe to safe context
Significantly fewer unsafe blocks through consolidation
Improved readability with clear safe/unsafe separation
Better maintainability - safe sections can be modified confidently

Key Patterns Established:

Dependency analysis: Check what actually needs to be unsafe vs what can be moved
Consolidation: Group unsafe operations together when possible
Clear separation: Safe setup operations first, unsafe API calls together
Minimal unsafe surface: Only the truly necessary operations remain unsafe

Please go through all the code and add concise comments suitable for someone still learning Vulkan. If you identify any areas where the code itself can be made more readable and concise, please let me know.

2. Builder Pattern Consistency: Some areas could use more consistent builder patterns for better readability, particularly in swapchain creation where we mix direct assignment with builders.

3. Error Handling Simplification: The

.map_err(|e| anyhow!("{}", e))

pattern could be simplified with custom error types or wrapper functions.

4. Magic Numbers: A few remaining magic numbers could become named constants:

```
4
```
(bytes per pixel) →
```
RGBA_BYTES_PER_PIXEL
```
```
60.0
```
(physics scaling) →
```
TARGET_FPS
```

5. Resource Management: The cleanup code in

destroy()

could potentially be reorganized for clearer resource lifetime management.

6. Swapchain Recreation: The swapchain recreation logic is scattered and could be consolidated for better maintainability.

We are currently working on some light refactoring to make this code more readable and maintainable.
The
.map_err(|e| anyhow!("{}", e))
pattern could be simplified with custom error types or wrapper functions.
A few remaining magic numbers could become named constants:
4
(bytes per pixel) →
RGBA_BYTES_PER_PIXEL
60.0
(physics scaling) →
TARGET_FPS

...

Let's take a look at swapchain creation and recreation next.

Some areas could use more consistent builder patterns for better readability, particularly in swapchain creation where we mix direct assignment with builders.

The swapchain recreation logic is scattered and could be consolidated for better maintainability.

Consistent Builder Pattern Implementation
Consolidated Recreation Logic

Should we fix this validation warning from NVIDIA?

Validation Performance Warning: [ BestPractices-NVIDIA-ClearColor-NotCompressed ] | MessageID = 0x916108d1 vkCmdBeginRendering(): pRenderingInfo->pColorAttachments[0] [NVIDIA] Clearing image with format VK_FORMAT_B8G8R8A8_SRGB without a 1.0f or 0.0f clear color. The clear will not get compressed in the GPU, harming performance. This can be fixed using a clear color of VkClearColorValue{0.0f, 0.0f, 0.0f, 0.0f}, or VkClearColorValue{1.0f, 1.0f, 1.0f, 1.0f}. Alternatively, use VK_FORMAT_R8G8B8A8_UNORM, VK_FORMAT_B8G8R8A8_UNORM, VK_FORMAT_A8B8G8R8_UNORM_PACK32, VK_FORMAT_A2R10G10B10_UNORM_PACK32, VK_FORMAT_A2B10G10R10_UNORM_PACK32, VK_FORMAT_R16G16B16A16_UNORM, VK_FORMAT_R16G16B16A16_SNORM, VK_FORMAT_R16G16B16A16_UINT, VK_FORMAT_R16G16B16A16_SINT, VK_FORMAT_R16G16B16A16_SFLOAT, VK_FORMAT_R32G32B32A32_SFLOAT, or VK_FORMAT_B10G11R11_UFLOAT_PACK32. Objects: 1 [0] VkCommandBuffer 0x21915374020

Issue Fixed:** ✅ NVIDIA validation warning about clear color compression

Change Made:

Changed the clear color from

[0.0, 0.0, 0.0, 1.0]

[0.0, 0.0, 0.0, 0.0]

in the

record_command_buffer

function

This provides optimal GPU compression for the
```
VK_FORMAT_B8G8R8A8_SRGB
```
swapchain format

We can run our benchmark with a set number of sprites and see the FPS and other metrics every second. But I'd like a benchmark script (for Git Bash on Windows for a maybe build.rs).

Run for a set number of frames, and take the average, but excluding the first 100 frames to allow for it to "warmup". We don't > currently have a command line option to terminate after a set number of frames (e.g. 10000 frames)

Then increase the number of sprites and run it all again. The script that I'm basing this idea on is here: > https://raw.githubusercontent.com/unitoftime/experiments/refs/heads/master/gophermark/batch/test.sh

From that data we should be able to generate a nice report using the averages from each of the runs.

Simple command line:
```
--frames N
```
to exit after N frames
Single output file: All results appended to
```
benchmark_results.txt
```

Clean result line:

BENCHMARK_RESULT: X sprites, Y FPS, Z sprites/sec

One-liner parsing: grep + sed + sort + printf in the benchmark script itself

A new version of Vulkanalia just came out, so I was able to switch the prelude from v1_3 to v1_4 to match with us using Vulkan 1.4. Are there any cleanups we can do based on this new prelude?

"Many modern applications use a hybrid approach - push descriptors for dynamic per-draw data (like transform matrices, material parameters) and traditional descriptor sets for longer-lived resources (like texture atlases, global uniform buffers)." Is that what you're doing here?

Streamlined Feature Enabling**:

After: Simplified to only enable features we actually use (
```
sampler_anisotropy
```
,
```
dynamic_rendering
```
,
```
synchronization2
```
)

We actually don't need sampler_anisotropy for 2D sprites, since they are rendered parallel to the screen.

We should decide what our minimum Vulkan version is based not only on VK_KHR_dynamic_rendering and VK_KHR_synchronization2, but everything else we're using.

If we do want a comprehensive fall back, this is the breakdown for those extensions.

Vulkan 1.3:

VK_KHR_dynamic_rendering: Core (just enable the feature) VK_KHR_synchronization2: Extension (add to extensions list + enable feature)

Vulkan 1.4:

VK_KHR_dynamic_rendering: Core (just enable the feature) VK_KHR_synchronization2: Core (just enable the feature)

Version compatibility: VK_KHR_dynamic_rendering:

Available as extension from Vulkan 1.1+ (requires VK_KHR_get_physical_device_properties2) Core in 1.3+

VK_KHR_synchronization2:

Available as extension from Vulkan 1.0+ Core in 1.4+

✅ Successfully Completed Changes

Proper Vulkan Version Requirements:
- Minimum: Vulkan 1.1.0 (for
```
VK_KHR_dynamic_rendering
```
  extension support)
- Preferred: Vulkan 1.3.0 (
```
VK_KHR_dynamic_rendering
```
  becomes core)
- Optimal: Vulkan 1.4.0 (
```
VK_KHR_synchronization2
```
  also becomes core)
Smart Extension Management:
- Vulkan 1.4+: Uses only core features, no additional extensions needed
- Vulkan 1.3: Uses core
```
dynamic_rendering
```
  , adds
```
VK_KHR_synchronization2
```
  extension
- Vulkan 1.1/1.2: Adds both
```
VK_KHR_dynamic_rendering
```
  and
```
VK_KHR_synchronization2
```
  as extensions

Please take a look at this extension and proposal.

https://registry.khronos.org/vulkan/specs/latest/man/html/VK_KHR_unified_image_layouts.html https://github.com/KhronosGroup/Vulkan-Docs/tree/main/proposals/VK_KHR_unified_image_layouts.adoc

Does Vulkanalia expose the new fields for VK_KHR_unified_image_layouts? How much would it improve our code and how would it impact our minimum requirements?

Final Assessment: VK_KHR_unified_image_layouts

✅ Vulkanalia Support Status

CONFIRMED: Available in Vulkanalia 0.29.0!

The types

vk::PhysicalDeviceUnifiedImageLayoutsFeaturesKHR

and related enums compile successfully

You were right to suspect it might be there - good catch!

🚫 But Driver Support is the Blocker

Current Driver Support (as of late 2024/early 2025):

NVIDIA: Beta drivers only
AMD RADV: Recently merged (very new)
Intel: No support yet
AMD Windows: Unknown status

Current Image Layout Usage: Your code uses several image layout transitions:

Swapchain Images:

UNDEFINED

→

COLOR_ATTACHMENT_OPTIMAL

→

PRESENT_SRC_KHR

Texture Loading:

UNDEFINED

→

TRANSFER_DST_OPTIMAL

→

SHADER_READ_ONLY_OPTIMAL

Descriptor Sets: References
```
SHADER_READ_ONLY_OPTIMAL
```

** Reduced Code Complexity**:

Could eliminate the entire
```
transition_image_layout
```
function for non-initialization cases
Simplified descriptor sets (always use
```
GENERAL
```
)
Fewer layout-specific code paths

"Could eliminate the entire
transition_image_layout
function for non-initialization cases" Since we would still need it for initialization cases, how much of a code reduction would that be?

Lines that could be eliminated:**

❌ 1 function call (5 lines):

TRANSFER_DST_OPTIMAL

→

SHADER_READ_ONLY_OPTIMAL

❌ 1 match arm in
```
transition_image_layout
```
(7 lines): The second case
❌ Some descriptor set references (1-2 lines): Change to `GENERAL

Can we make it so the sprites don't spawn until I press the spacebar? And make that controller by a const boolean that I can toggle if I want them to spawn immediately instead.

Immediate Mode (
```
SPAWN_SPRITES_IMMEDIATELY = true
```
)
Spacebar Mode (
```
SPAWN_SPRITES_IMMEDIATELY = false
```
)

We now have the vulkanalia-vma crate available for use. Please replace our manual memory allocation with VMA. Documentation is available at: https://docs.rs/vulkanalia-vma/latest/vulkanalia_vma/ This is a challenging upgrade, so we should make a plan first. And determine if we can break it down into smaller steps.

VMA Migration Complete! ✅

Awesome! Please run the app to see the best practices suggestions from AMD and NVIDIA, several around memory allocation. Now that we are using VMA, would some of these changes be easier? What would the magnitude of the code change be? Would it be more difficult to understand afterwards? What might the benefits be?

Our application is already doing several things well with VMA:

Using persistent mapping for frequently updated buffers (
```
MAPPED
```
flag)
Using appropriate memory usage types (
```
AutoPreferDevice
```
for GPU-only,
```
Auto
```
for CPU-to-GPU)
Proper memory type selection through VMA's automatic selection

NVIDIA Memory Priority Warning 🔴 **HIGH IMPACT
NVIDIA Pageable Device Local Memory 🟡 **MEDIUM IMPACT

The remaining warnings are unrelated to memory allocation:

Physical device features query (development practice)
Command pool reset strategy (command buffer management)
AMD pipeline layout size (descriptor set optimization)

Please review our extensions and features against what's available in core Vulkan versions to make sure everything is correct.

Please go through all the code and add concise comments suitable for someone still learning Vulkan. Since the order deallocation is important for proper cleanup, we should comment on that too (on struct fields, etc) as appropriate.

Maybe Later

VK_KHR_unified_image_layouts

I think we should give it a try. We can do this work on a branch that we can test out. I am running Windows with a non-beta AMD driver, and I can also test on another Windows computer with an NVIDIA driver.

"Nearly all GPU vendors are ready to support this extension on current-generation hardware" "In practice these image layouts typically map to just a handful of actual physical layouts or compression formats."

From what I've heard, some people have already tried simplifying to use VK_IMAGE_LAYOUT_GENERAL even without the extension.

RenderDoc Integration

// Add RenderDoc API integration
#[cfg(debug_assertions)]
use renderdoc::RenderDoc;

#[cfg(debug_assertions)]
fn capture_frame(&self) {
    if let Ok(mut rd) = RenderDoc::new() {
        rd.start_frame_capture(std::ptr::null(), std::ptr::null());
        // Your rendering code here
        rd.end_frame_capture(std::ptr::null(), std::ptr::null());
    }
}

We're starting a new Vulkan 1.4 project, which will eventually render sprites, but first lets get the classic triangle up on the screen.

For this project, this is the recommended list of crates.

vulkanalia provides the Vulkan API bindings

vulkanalia_vma for efficient buffer and image memory management (designed specifically for vulkanalia)

winit handles window creation and surface management

glam for MVP matrices (if needed) and sprite transformations with SIMD performance

image to load sprite textures from files

shaderc for compiling GLSL shaders to SPIR-V at runtime

anyhow for simplified error handling throughout your Vulkan code

bytemuck for safely converting your vertex structs to bytes for GPU upload

✅ What's Working:

Project Setup: Complete Cargo.toml with all recommended crates
Shader Compilation: GLSL shaders are being compiled to SPIR-V at runtime using shaderc
Vulkan Initialization: Proper instance, device, and swapchain creation
Triangle Rendering: The classic triangle with RGB vertex colors
Fixed Major Validation Errors:
- Dynamic viewport/scissor state issues resolved
- Clear color optimized for GPU compression
- Command buffer usage flags set correctly

🔧 Current Issues:

Semaphore Synchronization: The remaining validation error suggests using per-swapchain-image semaphores instead of per-frame semaphores
Some validation layer warnings: Mostly performance-related and informational

🎨 Features Implemented:

vulkanalia: Vulkan API bindings with window support
winit: Window creation and event handling
shaderc: Runtime GLSL to SPIR-V compilation
anyhow: Error handling throughout
bytemuck: Safe byte conversion (ready for vertex buffers)
Dynamic state: Viewport and scissor as dynamic states
Proper resource cleanup: All Vulkan objects properly destroyed

Major Issues Encountered

🔗 Dependency & Version Compatibility Issues

Rust Edition Compatibility (2024 vs 2021)
- Started with
```
edition = "2024"
```
  which caused massive unsafe block warnings
- The 2024 edition requires explicit
```
unsafe
```
  blocks even within
```
unsafe fn
```
- Solution: Downgraded to
```
edition = "2021"
```
  for smoother development
winit Version Incompatibility
- Initial attempt with
```
winit = "0.30"
```
  failed due to API changes
- ```
ApplicationHandler
```
  trait and
```
ActiveEventLoop
```
  don't exist in 0.28
- ```
WindowEvent::RedrawRequested
```
  doesn't exist in 0.28
- Solution: Downgraded to
```
winit = "0.28"
```
  and rewrote event handling
vulkanalia Feature Configuration
- Initially missing required features like
```
"window"
```
  and
```
"libloading"
```
- ```
LibloadingLoader
```
  wasn't available without the
```
libloading
```
  feature
- Solution: Added
```
vulkanalia = { version = "0.21", features = ["window", "libloading"] }
```
vulkanalia-vma Version Mismatch
- Tried
```
vulkanalia-vma = "0.21"
```
  to match vulkanalia version
- That version doesn't exist; available versions were 0.2.0 and 0.1.0
- Solution: Used
```
vulkanalia-vma = "0.2"
```
  (though we didn't end up using it)
Raw Window Handle Version Conflicts
- Multiple versions of
```
raw-window-handle
```
  crate in dependency tree
- winit and vulkanalia were using incompatible versions
- Caused trait implementation errors
- Solution: Version downgrade resolved the conflicts

🔧 Technical Implementation Issues

Device Initialization Problem
- Tried
```
Device::null()
```
  which doesn't exist
- Attempted
```
std::mem::zeroed()
```
  which caused undefined behavior warnings
- Solution: Restructured to avoid pre-initialization by moving Device to App struct
Vulkan API Version Confusion
- Started with
```
api_version(1, 4, 0)
```
  but validation layers complained about GPU-AV requiring 1.1+
- Some validation features weren't compatible with older API versions
- Solution: Used
```
api_version(1, 0, 0)
```
  for broader compatibility
Validation Layer Integration
- Many validation warnings about function pointer misuse
- Synchronization validation revealed complex semaphore issues
- Performance warnings about command buffer usage and clear colors

📝 Code Quality Issues

Unsafe Block Management
- With edition 2024, every Vulkan call needed explicit unsafe blocks
- Hundreds of compilation errors from missing unsafe blocks
- Solution: Edition downgrade + careful unsafe block placement
Clippy Warnings
- Manual slice size calculation warnings
- Unused variable warnings throughout
- Solution: Applied clippy fixes and used underscore prefixes

🎯 Vulkan-Specific Validation Errors

Dynamic State Configuration
- Pipeline used static viewport/scissor but code called dynamic state commands
- Solution: Added
```
VK_DYNAMIC_STATE_VIEWPORT
```
  and
```
VK_DYNAMIC_STATE_SCISSOR
```
Semaphore Synchronization
- Frame-based semaphores caused reuse conflicts with swapchain images
- Validation layer suggested per-image semaphores
- Partially resolved: Fixed other issues first, this remains
Performance Optimizations
- Clear color not GPU-optimized (non-0.0 or 1.0 values)
- Command buffer usage flags missing
```
ONE_TIME_SUBMIT
```
- Solution: Used
```
[0.0, 0.0, 0.0, 0.0]
```
  clear and proper flags

Unchanged vulkanalia v0.21.0 (available: v0.28.0) Unchanged winit v0.28.7 (available: v0.30.11)

Please upgrade vulkanalia in this project to latest. This may require a newer version of winit with a compatible version of raw-window-handle, which may also require fixes to breaking changes. I'm not concerned if we're on the latest version of winit -- just whatever is compatible with the latest vulkanalia.

Feel free to upgrade other crates as well, but perhaps not all at once.

✅ Successfully upgraded all compatible dependencies:

vulkanalia: 0.21.0 → 0.28.0 (latest)
winit: 0.28.7 → 0.29.15 (compatible with vulkanalia's raw-window-handle)
glam: 0.24.0 → 0.30.4 (latest)
shaderc: 0.8.3 → 0.9.1 (latest)

This is a Vulkan triangle rendering app using Vulkanalia which I'd like to modernize. Vulkan 1.4 should be available, which I'd like to require. To start, let's also make sure we're using:

VkViewport, vkCmdSetViewport

VkRect2D, vkCmdSetScissor

✅ Vulkan 1.4 Support

Updated the API version to
```
vk::make_version(1, 4, 0)
```
in the instance creation
While vulkanalia 0.28 doesn't have a v1_4 prelude yet, the app now requests Vulkan 1.4 API version

✅ Fixed Validation Layer Errors The major issue was with semaphore synchronization. I implemented a proper solution:

Per-swapchain-image semaphores: Created separate
```
image_available_semaphores
```
and
```
render_finished_semaphores
```
for each swapchain image (typically 3) instead of per frame in flight (2)
Proper indexing: Used frame-based indexing for acquire semaphores but image-based indexing for render finished semaphores
Fixed cleanup: Updated the destroy function to properly clean up all created semaphores

This is a Vulkan 1.4 app using Vulkanalia. I think the next extension to adopt as part of our modernization effort is:

VK_KHR_synchronization2

Changes Made:

Added Extension: Added
```
vk::KHR_SYNCHRONIZATION2_EXTENSION.name
```
to the device extensions list

Enabled Feature: Added

VkPhysicalDeviceSynchronization2Features

with

synchronization2

set to

true

Modernized Queue Submission: Replaced
```
vk::SubmitInfo
```
with
```
vk::SubmitInfo2
```
using:
- ```
vk::SemaphoreSubmitInfo
```
  for more granular semaphore control
- ```
vk::CommandBufferSubmitInfo
```
  for command buffer submission
- ```
vk::PipelineStageFlags2
```
  for enhanced pipeline stage specification
- ```
queue_submit2()
```
  instead of
```
queue_submit()
```

Key Benefits:

Enhanced Synchronization: More precise pipeline stage control with
```
VkPipelineStageFlags2
```
Cleaner API: Separate submission info structures for semaphores and command buffers

When a KHR extension becomes core:

Vulkan 1.2 and below: Need both extension + feature
Vulkan 1.3+ (when targeting the core version): Only need the feature
Vulkan 1.3+ (when targeting older versions): Still need extension + feature

The next extension to adopt as part of our modernization effort is: VK_KHR_dynamic_rendering

Major Changes:

Feature Enablement: Added

VkPhysicalDeviceDynamicRenderingFeatures

with

dynamicRendering

enabled

Removed Legacy Components:
- Eliminated
```
render_pass
```
  field from
```
AppData
```
- Eliminated
```
framebuffers
```
  field from
```
AppData
```
- Removed
```
create_render_pass()
```
  function
- Removed
```
create_framebuffers()
```
  function
Pipeline Modernization: Updated pipeline creation to use
```
VkPipelineRenderingCreateInfo
```
instead of render pass

Command Buffer Modernization: Replaced render pass commands with dynamic rendering:

cmd_begin_render_pass()

→

cmd_begin_rendering()

cmd_end_render_pass()

→

cmd_end_rendering()

Added explicit

VkRenderingInfo

with

VkRenderingAttachmentInfo

Synchronization Enhancement: Added explicit image layout transitions using synchronization2:
- ```
UNDEFINED
```
  →
```
COLOR_ATTACHMENT_OPTIMAL
```
  before rendering
- ```
COLOR_ATTACHMENT_OPTIMAL
```
  →
```
PRESENT_SRC_KHR
```
  after rendering

Do we need feature enablement for VK_KHR_maintenance6?

Maintenance Extension Status in Vulkan 1.4:

Extension	Core Status	Feature Structure	Requires Enablement
maintenance4	Core in 1.3+	`VkPhysicalDeviceMaintenance4Features`	YES
maintenance5	Core in 1.4	`VkPhysicalDeviceMaintenance5Features`	YES
maintenance6	Core in 1.4	None	**NO

✅ maintenance4 Features (now enabled):

Early pipeline layout destruction
```
LocalSizeId
```
shader support
Consistent image alignment requirements
Relaxed push constant initialization
Interface matching improvements

✅ maintenance5 Features (now enabled):

Enhanced command buffer functionality
Better vertex buffer binding
Improved multisample operations
Device loss detection improvements
Additional API robustness

✅ maintenance6 Features (automatic):

Enhanced memory binding error reporting
Fragment shading rate improvements
New descriptor binding commands
Extended format support

Let's proceed to replace the triangle with a textured quad using ./ferris.png loaded via the image crate. Use modern Vulkan 1.4 features such as push constants and push descriptors where appropriate.

Textured Quad Rendering:

Replaced hardcoded triangle vertices with a quad
Added texture coordinates for UV mapping
Renders ferris.png texture using the image crate
Push Descriptors: Using core
```
cmd_push_descriptor_set()
```
instead of traditional descriptor sets

The textured quad we have right now needs to become a Sprite. We want to set a logical resolution, such as 640x360 and have pixel-perfect scaling (clamp) to the window size. Use letterboxing/pillarboxing to maintain the aspect ratio. Add the glam crate so we can use the types it defines.

The sprite system is now:

✅ Using logical coordinates (640x360 resolution)
✅ Pixel-perfect scaling with aspect ratio preservation
✅ Letterboxing/pillarboxing for different window sizes
✅ Native sprite dimensions (99x70) matching the actual PNG

Lets fill in a background color in the logical area so that the letterbox/pillarbox is more obvious. Lets define the window size we start with in constants as well.

```
INITIAL_WINDOW_WIDTH
```
: 1920 pixels
```
INITIAL_WINDOW_HEIGHT
```
: 1080 pixels
Easy to modify for different default window sizes
Blue background color (
```
[0.3, 0.5, 0.7, 1.0]
```
) for the entire screen

I made some changes to the window size, logical size, and initial sprite position. Please leave those alone for now. We need to enable a blend mode. The PNG has an alpha channel and should render with a transparent background, but it is currently rendering with a black background.

🎯 Issue Identified:

The pipeline was configured with
```
blend_enable(false)
```
Blend factors were set to
```
ONE
```
and
```
ZERO
```
(no blending)
This caused the PNG's alpha channel to be ignored, resulting in black backgrounds

🔧 Fix Applied:

Enabled Blending:
```
blend_enable(true)
```
Source Factor:
```
SRC_ALPHA
```
- uses the sprite's alpha channel
Destination Factor:
```
ONE_MINUS_SRC_ALPHA
```
- uses the inverse of sprite's alpha
Blend Operation:
```
ADD
```
- standard alpha blending formula

Nice. Next we want to render a variable number of Sprites based on a command line argument, e.g.
cargo run 100
.

🎯 New Features:

Command Line Argument Support
- ```
cargo run
```
  - renders 1 sprite (default)
- ```
cargo run 10
```
  - renders 10 sprites
- ```
cargo run 100
```
  - renders 100 sprites
- Invalid arguments default to 1 sprite
Dynamic Buffer Management
- Vertex buffer size scales with sprite count
- Index buffer generates proper indices for multiple quads
- Each sprite uses 4 vertices and 6 indices

Now for the fun part. We want the sprites to start at random positions and bounce around, while handling collisions with the screen edges. This Go code is an example of the movement logic I'd like to implement: https://raw.githubusercontent.com/sedyh/ebitengine-bunny-mark/refs/heads/master/bench/bunny.go

🎮 Physics Constants (easily tweakable):

```
GRAVITY
```
- Downward acceleration strength
```
BOUNCE_DAMPING
```
- Energy loss on ground impact

I think they jump higher in the Go version. It's probably related to the size of our sprite and the resolution I chose, but I'd like to keep those the same. Should we making the damping less?

🎯 Physics Improvements:

Reduced Damping: 0.85 → 0.90 (less energy loss on bounce)
Lighter Gravity: 0.95 → 0.5 (sprites stay airborne longer)
Higher Initial Velocities:
- Horizontal: -2.5/2.5 → -5.0/5.0 (doubled)
- Vertical: 2.5/5.0 → 5.0/10.0 (doubled)
Random Upward Boost: Added 50% chance for extra bounce energy (0-9 units)

I like it! The next thing is some basic metrics. We don't have font rendering like the Go version, so logging to the console will have to suffice. https://raw.githubusercontent.com/sedyh/ebitengine-bunny-mark/refs/heads/master/bench/metrics.go Also see this DX11 version that is similar to what we're building, but with different movement. https://raw.githubusercontent.com/nathany/ferris-mark-dx/refs/heads/master/src/main.rs

🎯 Metrics Features Implemented:

Real-time Performance Tracking
- FPS (Frames Per Second): Actual rendering performance
- Frame Time: Average milliseconds per frame
- Sprites/Second: Key throughput metric for benchmarking
- Sprite Count: Current number of active sprites
- Resolution: Current window/swapchain resolution
System Information
- GPU Name: Hardware identification
- Vulkan API Version: Graphics API version
- Logical Resolution: Game coordinate system
- Physics Parameters: Gravity and bounce damping values

🔧 Technical Implementation:

Frame Timing: High-precision measurement using
```
Instant
```
Rolling Averages: Accumulates frame times over 1-second intervals
Non-intrusive: Minimal performance overhead
Automatic Logging: Updates every second in console

My window scaling in Windows 11 is set to 150% on a 4K monitor. That would explain why the initial window is larger than 1/4 of my 4K screen, and why the resolution logged is like this:

=== Ferris Mark VK - Vulkan Sprite Benchmark === Rendering 1000 sprites Logical resolution: 1920x1080 Initial window size: 1920x1080 Physics: gravity=0.5, bounce_damping=0.9 Performance metrics will be logged every second...

GPU: AMD Radeon RX 9070 XT Vulkan API: 1.4.308 FPS: 133.4 | Frame time: 5.66ms | Sprites: 1000 | Sprites/sec: 133377 | Resolution: 2880x1620

Could we make it so the initial window size is 1920x1080 like requested, even if Windows 11 scaling is enabled?

DPI Scaling Fix Summary

I've successfully resolved the Windows DPI scaling issue! Here's what was changed:

🎯 Problem Identified:

Windows 11 with 150% scaling was causing the window to be created at 2880x1620 instead of 1920x1080
This happened because
```
LogicalSize
```
gets multiplied by the DPI scale factor
The actual rendered resolution was 1.5x larger than intended

Debug build:

FPS: 165.0 | Frame time: 6.00ms | Sprites: 1000 | Sprites/sec: 164991 | Resolution: 1920x1080
FPS: 146.4 | Frame time: 6.76ms | Sprites: 1000 | Sprites/sec: 146408 | Resolution: 1920x1080
FPS: 165.0 | Frame time: 6.00ms | Sprites: 1000 | Sprites/sec: 165009 | Resolution: 1920x1080

Now we have our sprite rendering working, so it's time to optimize! I found an article about rendering many sprites in Vulkan. What do you think of it? Is it all applicable to a modern Vulkan 1.4 implementation or is there some improvements that could be made? Also, we're only rendering one sprite texture right now and no text, so we could keep things a little simpler. Validation layers for performance and best practices are also now enabled. Let's make a plan to make this run faster!

Optimization Plan

Here's a step-by-step plan to dramatically improve performance:

Phase 1: Eliminate Vertex Buffer Updates

Goal: Remove the expensive vertex buffer mapping/updating

Switch to procedural quad generation using the
```
gl_VertexIndex
```
technique
Create a sprite command buffer with transform, UV, and color data
Use instanced rendering with one draw call

Phase 2: Implement Sprite Commands

Goal: GPU-driven sprite rendering

Create sprite command structure (simplified from article since you only have one texture)
Upload sprite data as storage buffer instead of vertex attributes
Use buffer device addresses for modern Vulkan 1.4 approach

Phase 3: Add Performance Optimizations

Goal: Squeeze out maximum performance

Implement frustum culling on CPU side
Sort sprites by depth/state for better cache usage
Add performance validation layer feedback

Phase 4: Future Enhancements

Goal: Prepare for more complex scenarios

Add bindless texture support for when you need multiple textures
Implement batching system for different primitive types
Consider mesh shaders for more complex sprite effects

Please proceed with phase 1. I do some research on the subsequent phases before we tackle those.

Issues Encountered & Solutions:

Buffer device address validation error - Fixed by adding
```
VK_MEMORY_ALLOCATE_DEVICE_ADDRESS_BIT
```
flag
Invisible sprites - Fixed the procedural vertex generation bit manipulation
Shader compilation - Debugged with simpler test shaders first
bytemuck compatibility - Used
```
[[f32; 4]; 4]
```
instead of
```
Mat4
```
for POD types

Please correct all clippy warnings and have a look at the best practices mentioned in the validation layers (which I just re-enabled).

I'm not sure how far I want to go down the GPU-driven command, because I'm concerned about how difficult it may be to debug. Maybe we can take another look at the plan.

Validation Layer Best Practices Issues:

Small memory allocations - We're making many small allocations instead of sub-allocating from larger blocks
Command pool flags - Recommendation about pool resets
Pipeline layout size - The layout is too large (likely the buffer device address in push constants)

Current State - Phase 1 Complete ✅**

Procedural vertex generation (easier to debug than complex buffer layouts)
Instanced rendering (one draw call, but still CPU-controlled)
Standard descriptor sets (debugger-friendly, shows up in graphics debuggers)
~120-140 FPS with 1000 sprites

Recommended Next Steps - Debugger-Friendly Focus:

Phase 2A: Memory Management Optimization

Goal: Address validation layer warnings while keeping debugging simple

Implement memory allocator (VMA or custom) for sub-allocation
Combine small allocations into larger blocks
Fix command pool flags for better performance

Phase 2B: CPU-Side Optimizations

Goal: Optimize the CPU side while keeping GPU side simple

Frustum culling on CPU (easy to debug, step through in debugger)
Sort sprites by depth/texture for better cache performance
SIMD optimizations for physics updates (explicit, debuggable)

Phase 2C: Smart Batching

Goal: Better batching without losing debuggability

Texture atlas support (multiple sprites, one texture)
State sorting (group by blend mode, shader variants)
Debug visualization for batch boundaries

Alternative to GPU-Driven Commands:

Instead of full GPU-driven rendering, consider:

Hybrid approach: CPU prepares commands, GPU consumes them (current approach)
Debug modes: Toggle between optimized and debug-friendly paths
Validation integration: Use validation layers for performance insights
Graphics debugger friendly: Standard descriptor sets, named resources

Phase 3+: Advanced (Optional)

Bindless textures (when you need multiple textures)
Compute-based culling (optional, togglable)
Mesh shaders (very advanced, R&D territory)

I'm not seeing a significant difference with batching. I'd like to disable vsync by default and have a --vsync command line flag to enable it.

I'd like our optimizations to focus on consistent frame pacing. Which optimizations could benefit that most?

Outside of optimization, I have no current plans to extend this particular application with multiple sprite textures, etc. We're using Vulkan 1.4, but my goal is to take advantage of the new features that make Vulkan easier to use. So let's keep it simple.

FPS: 1816.2 | Frame time: 0.51ms | Sprites: 1000 | Sprites/sec: 1816220 | Resolution: 1920x1080

The key optimizations for consistent frame pacing are:

A. Memory Management & Allocation Consistency

Issue: Currently making small allocations each frame Solution: Pre-allocate or use memory pools

B. CPU-GPU Synchronization

Issue: Currently using

map_memory

every frame Solution: Use persistent mapped memory or double-buffered approach

C. Command Buffer Management

Issue: Resetting command buffers each frame Solution: Pre-record static parts

✅ What We've Successfully Implemented:

VSync Control:
```
--vsync
```
flag (defaults to disabled)
- Without VSync: ~1600-1700 FPS
- With VSync: ~115-120 FPS (adaptive based on display)
Modern Vulkan 1.4 Features (Simple & Effective):
- Dynamic rendering (no render passes)
- Buffer device addresses (with descriptor fallback)
- Maintenance features enabled
- Validation layers for best practices
Frame Pacing Optimizations:
- Persistent mapped memory (eliminates map/unmap overhead)
- Instanced rendering (one draw call for all sprites)
- Procedural vertex generation (no vertex buffers)

Let's apply the glam improvement for SIMD.

FPS: 82.9 | Frame time: 11.99ms | Sprites: 50000 | Sprites/sec: 4146880 | Resolution: 1920x1080

🎉 SIMD Optimization Results Summary

Performance Improvements:

Code cleaner: Vec2 operations are more readable than separate x/y components
SIMD benefits: glam's Vec2 uses CPU SIMD instructions for parallel operations
Memory layout: Better cache efficiency with packed Vec2 structures

You mentioned some sorting and culling improvements? How much impact could that have? Would it cull sprites that are fully occluded by other sprites, taking into account alpha transparency? Or is it more just a viewport thing (we don't currently have sprites outside of the viewport)?

🤔 Your Specific Constraints:**

Single texture → No texture state sorting benefits
Single shader → No shader state sorting benefits
Same-sized sprites → No size-based batching benefits
Viewport-constrained → No frustum culling benefits

✅ What Actually Helped:**

Removing alpha discard: Better tile-based GPU performance

Alright. That was a good optimization session! Please summarize what we did, what we chose not to do (and why), and what we might yet do. Thanks.

🎯 Optimization Session Summary

✅ What We Successfully Implemented

Phase 1: Core Architecture Overhaul

Procedural vertex generation: Eliminated vertex buffers entirely, generate quads in vertex shader using
```
gl_VertexIndex
```
Instanced rendering: One
```
vkCmdDraw(6, sprite_count, 0, 0)
```
call instead of multiple draw calls
Sprite command system: GPU buffer with transform matrices, colors, and UV coordinates
Buffer device addresses → Descriptor sets: Started with modern buffer device addresses, simplified to standard descriptor sets for better debugging

Phase 2: Performance & Usability Improvements

VSync control: Added
```
--vsync
```
flag (defaults to disabled for benchmarking)
Persistent mapped memory: Eliminated expensive
```
map_memory
```
/
```
unmap_memory
```
calls every frame
SIMD physics optimization: Replaced individual
```
f32
```
components with
```
glam::Vec2
```
for vectorized operations
Alpha discard removal: Removed fragment shader discard for better tile-based GPU performance

Phase 3: Code Quality

Fixed all clippy warnings: Removed unused vertex buffer code, cleaned up imports
Addressed validation layer best practices: Fixed buffer device address allocation flags
Modern Vulkan 1.4 features: Dynamic rendering, maintenance features, proper feature enablement

What We Chose NOT to Do (And Why)

Complex GPU-Driven Commands

Why avoided: Debugging concerns (your explicit request)
Alternative chosen: CPU-prepared commands with GPU consumption via descriptor sets
Trade-off: Slightly less optimal but much more debugger-friendly

Frustum/Viewport Culling

Why avoided: Sprites are constrained to viewport bounds anyway
Impact: Would provide ~0-2% benefit at best

Occlusion Culling with Alpha Testing

Why avoided: Massive implementation complexity for 2D sprites
Would require: Depth sorting, per-pixel alpha analysis, visibility calculations
Trade-off: Theoretical benefits not worth the development/maintenance cost

Spatial Sorting for Cache Locality

Why removed: Sorting overhead every frame exceeded cache benefits
Tested: Showed 50% performance decrease (380 FPS → 200 FPS)
Modern reality: CPU cache prediction is quite good

Multiple Texture/Shader Support

Why avoided: Your explicit requirement to keep it simple
Current constraint: Single texture, single shader = no state sorting benefits

🔮 What We Might Yet Do**

Low-Hanging Fruit (If Desired)

Vulkan Memory Allocator (VMA)
- Benefit: Eliminates validation layer "small allocation" warnings
- Effort: Low (add dependency, replace allocation calls)
- Impact: Cleaner validation, better memory efficiency
Frame Rate Limiting
- Feature:
```
--target-fps N
```
  flag for testing consistency
- Benefit: Better frame pacing analysis tools
- Effort: Very low
SIMD Physics Further Optimization
- Opportunity: Batch process multiple sprites with SIMD
- Benefit: Potential 2-4x physics performance
- Effort: Medium (requires algorithm restructuring)

Excellent. Thanks! I'm seeing a lot of different shader files. Do we still need them all? Beyond the validation layer differences in config.toml, do we have other differences between release/debug? Do we need to?

✅ Build Configuration Optimized**

Debug Build (
cargo run
)

Validation layers: ✅ Enabled automatically
Debug symbols: ✅ Enabled
Optimization: Level 1 (good debug performance)
Purpose: Development, debugging, validation

Release Build (
cargo run --release
)

Validation layers: ❌ Disabled automatically
Debug symbols: ❌ Stripped
Optimization: Level 3 + LTO + codegen-units=1
Binary size: Minimized with
```
strip = true
```
Panic behavior:
```
abort
```
for smaller binaries
Purpose: Benchmarking, production

I think that the VALIDATION_ENABLED logging may be a little inaccurate? When it says "Validation layers: Disabled (Release)", are we sure the validation layers are disabled? Or are they still enabled because I have them enabled in vkconfig?

✅ Validation Layer Reality Check**

Our app control: We can choose whether to request validation layers
vkconfig override: Can force validation layers on ANY Vulkan app
End user systems: Won't have vkconfig, so validation layers won't run

Code review

Please add constants for sprite_width and sprite_height.

Please use the fastrand crate instead of generating our own pseudo-random values.

I wonder if we should entirely remove the VALIDATION_ENABLED and VALIDATION_LAYER stuff from our code and config.toml, and let that be completely controlled by vkconfig? I think we can also remove enabled_layer_names(&layers) in a few places if it's always going to be empty?

Is there any code that we're no longer using? Or any other small cleanups we could do?
cargo clippy -- -W clippy::all -W clippy::pedantic -W clippy::nursery

Code Cleanup Changes Made:

Simplified
```
log_gpu_info
```
function:
- Removed unnecessary
```
Result<()>
```
  return type since it never fails
- Removed the
```
Ok(())
```
  return and
```
?
```
  call
Removed unused variables:
- Deleted unused
```
viewport
```
  and
```
scissor
```
  variables in
```
create_pipeline
```
- These weren't needed since we use dynamic viewport/scissor states
Fixed underscore-prefixed variable:
- Removed
```
_
```
  prefix from
```
instance
```
  parameter in
```
create_command_pool
```
  since it's actually used
Improved type conversions:
- Used
```
u64::from()
```
  instead of
```
as u64
```
  cast for lossless conversion
- Used safer pointer casting with `(&raw const push_constants).cast::()

This may be a tricky one that will take some thought. Please make a list of functions that have unsafe blocks spanning the entire function and also determine which calls (e.g. to vulkanalia) need to be wrapped in unsafe blocks. From that, make a plan for which unsafe blocks could be narrowed or split such that more lines of code are considered safe.

Let's proceed with phase 1. Keep readability in mind. It may be better to have a few lines in an unsafe block that don't need to be if the code is more concise. But any large blocks of safe code should be outside of unsafe blocks if possible. Given the magnitude of these changes, it may be a good idea to tackle 1 function first and ensure everything compiles and works before moving on.

Well done. Proceed through each of the other 4 candidates you identified, but test the build after completing each function before continuing onto the next.

Feel free to remove the // SAFE: and // UNSAFE: comments that you added during this process.

Nice work. Are there any other functions that would benefit from a refactor of the unsafe blocks? Go for it with log_gpu_info(). Please also add your SAFE/UNSAFE comments to App::create and create_instance. Then we can both think about those two a little more.

Please proceed. It may be worth considering whether some of the safe lines can be moved. For example, does AppData need to come after loader/entry for it to work, or could it come before the unsafe block entirely? It that sort of consolidation is possible, we could both have fewer unsafe lines without increasing the number of unsafe blocks (making it less readable).

Total Impact Across All Refactoring:

~260+ lines moved from unsafe to safe context
Significantly fewer unsafe blocks through consolidation
Improved readability with clear safe/unsafe separation
Better maintainability - safe sections can be modified confidently

Key Patterns Established:

Dependency analysis: Check what actually needs to be unsafe vs what can be moved
Consolidation: Group unsafe operations together when possible
Clear separation: Safe setup operations first, unsafe API calls together
Minimal unsafe surface: Only the truly necessary operations remain unsafe

Please go through all the code and add concise comments suitable for someone still learning Vulkan. If you identify any areas where the code itself can be made more readable and concise, please let me know.

2. Builder Pattern Consistency: Some areas could use more consistent builder patterns for better readability, particularly in swapchain creation where we mix direct assignment with builders.

3. Error Handling Simplification: The

.map_err(|e| anyhow!("{}", e))

pattern could be simplified with custom error types or wrapper functions.

4. Magic Numbers: A few remaining magic numbers could become named constants:

```
4
```
(bytes per pixel) →
```
RGBA_BYTES_PER_PIXEL
```
```
60.0
```
(physics scaling) →
```
TARGET_FPS
```

5. Resource Management: The cleanup code in

destroy()

could potentially be reorganized for clearer resource lifetime management.

6. Swapchain Recreation: The swapchain recreation logic is scattered and could be consolidated for better maintainability.

We are currently working on some light refactoring to make this code more readable and maintainable.
The
.map_err(|e| anyhow!("{}", e))
pattern could be simplified with custom error types or wrapper functions.
A few remaining magic numbers could become named constants:
4
(bytes per pixel) →
RGBA_BYTES_PER_PIXEL
60.0
(physics scaling) →
TARGET_FPS

...

Let's take a look at swapchain creation and recreation next.

Some areas could use more consistent builder patterns for better readability, particularly in swapchain creation where we mix direct assignment with builders.

The swapchain recreation logic is scattered and could be consolidated for better maintainability.

Consistent Builder Pattern Implementation
Consolidated Recreation Logic

Should we fix this validation warning from NVIDIA?

Validation Performance Warning: [ BestPractices-NVIDIA-ClearColor-NotCompressed ] | MessageID = 0x916108d1 vkCmdBeginRendering(): pRenderingInfo->pColorAttachments[0] [NVIDIA] Clearing image with format VK_FORMAT_B8G8R8A8_SRGB without a 1.0f or 0.0f clear color. The clear will not get compressed in the GPU, harming performance. This can be fixed using a clear color of VkClearColorValue{0.0f, 0.0f, 0.0f, 0.0f}, or VkClearColorValue{1.0f, 1.0f, 1.0f, 1.0f}. Alternatively, use VK_FORMAT_R8G8B8A8_UNORM, VK_FORMAT_B8G8R8A8_UNORM, VK_FORMAT_A8B8G8R8_UNORM_PACK32, VK_FORMAT_A2R10G10B10_UNORM_PACK32, VK_FORMAT_A2B10G10R10_UNORM_PACK32, VK_FORMAT_R16G16B16A16_UNORM, VK_FORMAT_R16G16B16A16_SNORM, VK_FORMAT_R16G16B16A16_UINT, VK_FORMAT_R16G16B16A16_SINT, VK_FORMAT_R16G16B16A16_SFLOAT, VK_FORMAT_R32G32B32A32_SFLOAT, or VK_FORMAT_B10G11R11_UFLOAT_PACK32. Objects: 1 [0] VkCommandBuffer 0x21915374020

Issue Fixed:** ✅ NVIDIA validation warning about clear color compression

Change Made:

Changed the clear color from

[0.0, 0.0, 0.0, 1.0]

[0.0, 0.0, 0.0, 0.0]

in the

record_command_buffer

function

This provides optimal GPU compression for the
```
VK_FORMAT_B8G8R8A8_SRGB
```
swapchain format

We can run our benchmark with a set number of sprites and see the FPS and other metrics every second. But I'd like a benchmark script (for Git Bash on Windows for a maybe build.rs).

Run for a set number of frames, and take the average, but excluding the first 100 frames to allow for it to "warmup". We don't > currently have a command line option to terminate after a set number of frames (e.g. 10000 frames)

Then increase the number of sprites and run it all again. The script that I'm basing this idea on is here: > https://raw.githubusercontent.com/unitoftime/experiments/refs/heads/master/gophermark/batch/test.sh

From that data we should be able to generate a nice report using the averages from each of the runs.

Simple command line:
```
--frames N
```
to exit after N frames
Single output file: All results appended to
```
benchmark_results.txt
```

Clean result line:

BENCHMARK_RESULT: X sprites, Y FPS, Z sprites/sec

One-liner parsing: grep + sed + sort + printf in the benchmark script itself

A new version of Vulkanalia just came out, so I was able to switch the prelude from v1_3 to v1_4 to match with us using Vulkan 1.4. Are there any cleanups we can do based on this new prelude?

"Many modern applications use a hybrid approach - push descriptors for dynamic per-draw data (like transform matrices, material parameters) and traditional descriptor sets for longer-lived resources (like texture atlases, global uniform buffers)." Is that what you're doing here?

Streamlined Feature Enabling**:

After: Simplified to only enable features we actually use (
```
sampler_anisotropy
```
,
```
dynamic_rendering
```
,
```
synchronization2
```
)

We actually don't need sampler_anisotropy for 2D sprites, since they are rendered parallel to the screen.

We should decide what our minimum Vulkan version is based not only on VK_KHR_dynamic_rendering and VK_KHR_synchronization2, but everything else we're using.

If we do want a comprehensive fall back, this is the breakdown for those extensions.

Vulkan 1.3:

VK_KHR_dynamic_rendering: Core (just enable the feature) VK_KHR_synchronization2: Extension (add to extensions list + enable feature)

Vulkan 1.4:

VK_KHR_dynamic_rendering: Core (just enable the feature) VK_KHR_synchronization2: Core (just enable the feature)

Version compatibility: VK_KHR_dynamic_rendering:

Available as extension from Vulkan 1.1+ (requires VK_KHR_get_physical_device_properties2) Core in 1.3+

VK_KHR_synchronization2:

Available as extension from Vulkan 1.0+ Core in 1.4+

✅ Successfully Completed Changes

Proper Vulkan Version Requirements:
- Minimum: Vulkan 1.1.0 (for
```
VK_KHR_dynamic_rendering
```
  extension support)
- Preferred: Vulkan 1.3.0 (
```
VK_KHR_dynamic_rendering
```
  becomes core)
- Optimal: Vulkan 1.4.0 (
```
VK_KHR_synchronization2
```
  also becomes core)
Smart Extension Management:
- Vulkan 1.4+: Uses only core features, no additional extensions needed
- Vulkan 1.3: Uses core
```
dynamic_rendering
```
  , adds
```
VK_KHR_synchronization2
```
  extension
- Vulkan 1.1/1.2: Adds both
```
VK_KHR_dynamic_rendering
```
  and
```
VK_KHR_synchronization2
```
  as extensions

Please take a look at this extension and proposal.

https://registry.khronos.org/vulkan/specs/latest/man/html/VK_KHR_unified_image_layouts.html https://github.com/KhronosGroup/Vulkan-Docs/tree/main/proposals/VK_KHR_unified_image_layouts.adoc

Does Vulkanalia expose the new fields for VK_KHR_unified_image_layouts? How much would it improve our code and how would it impact our minimum requirements?

Final Assessment: VK_KHR_unified_image_layouts

✅ Vulkanalia Support Status

CONFIRMED: Available in Vulkanalia 0.29.0!

The types

vk::PhysicalDeviceUnifiedImageLayoutsFeaturesKHR

and related enums compile successfully

You were right to suspect it might be there - good catch!

🚫 But Driver Support is the Blocker

Current Driver Support (as of late 2024/early 2025):

NVIDIA: Beta drivers only
AMD RADV: Recently merged (very new)
Intel: No support yet
AMD Windows: Unknown status

Current Image Layout Usage: Your code uses several image layout transitions:

Swapchain Images:

UNDEFINED

→

COLOR_ATTACHMENT_OPTIMAL

→

PRESENT_SRC_KHR

Texture Loading:

UNDEFINED

→

TRANSFER_DST_OPTIMAL

→

SHADER_READ_ONLY_OPTIMAL

Descriptor Sets: References
```
SHADER_READ_ONLY_OPTIMAL
```

** Reduced Code Complexity**:

Could eliminate the entire
```
transition_image_layout
```
function for non-initialization cases
Simplified descriptor sets (always use
```
GENERAL
```
)
Fewer layout-specific code paths

"Could eliminate the entire
transition_image_layout
function for non-initialization cases" Since we would still need it for initialization cases, how much of a code reduction would that be?

Lines that could be eliminated:**

❌ 1 function call (5 lines):

TRANSFER_DST_OPTIMAL

→

SHADER_READ_ONLY_OPTIMAL

❌ 1 match arm in
```
transition_image_layout
```
(7 lines): The second case
❌ Some descriptor set references (1-2 lines): Change to `GENERAL

Can we make it so the sprites don't spawn until I press the spacebar? And make that controller by a const boolean that I can toggle if I want them to spawn immediately instead.

Immediate Mode (
```
SPAWN_SPRITES_IMMEDIATELY = true
```
)
Spacebar Mode (
```
SPAWN_SPRITES_IMMEDIATELY = false
```
)

We now have the vulkanalia-vma crate available for use. Please replace our manual memory allocation with VMA. Documentation is available at: https://docs.rs/vulkanalia-vma/latest/vulkanalia_vma/ This is a challenging upgrade, so we should make a plan first. And determine if we can break it down into smaller steps.

VMA Migration Complete! ✅

Awesome! Please run the app to see the best practices suggestions from AMD and NVIDIA, several around memory allocation. Now that we are using VMA, would some of these changes be easier? What would the magnitude of the code change be? Would it be more difficult to understand afterwards? What might the benefits be?

Our application is already doing several things well with VMA:

Using persistent mapping for frequently updated buffers (
```
MAPPED
```
flag)
Using appropriate memory usage types (
```
AutoPreferDevice
```
for GPU-only,
```
Auto
```
for CPU-to-GPU)
Proper memory type selection through VMA's automatic selection

NVIDIA Memory Priority Warning 🔴 **HIGH IMPACT
NVIDIA Pageable Device Local Memory 🟡 **MEDIUM IMPACT

The remaining warnings are unrelated to memory allocation:

Physical device features query (development practice)
Command pool reset strategy (command buffer management)
AMD pipeline layout size (descriptor set optimization)

Please review our extensions and features against what's available in core Vulkan versions to make sure everything is correct.

Please go through all the code and add concise comments suitable for someone still learning Vulkan. Since the order deallocation is important for proper cleanup, we should comment on that too (on struct fields, etc) as appropriate.

Maybe Later

VK_KHR_unified_image_layouts

I think we should give it a try. We can do this work on a branch that we can test out. I am running Windows with a non-beta AMD driver, and I can also test on another Windows computer with an NVIDIA driver.

"Nearly all GPU vendors are ready to support this extension on current-generation hardware" "In practice these image layouts typically map to just a handful of actual physical layouts or compression formats."

From what I've heard, some people have already tried simplifying to use VK_IMAGE_LAYOUT_GENERAL even without the extension.

RenderDoc Integration

// Add RenderDoc API integration
#[cfg(debug_assertions)]
use renderdoc::RenderDoc;

#[cfg(debug_assertions)]
fn capture_frame(&self) {
    if let Ok(mut rd) = RenderDoc::new() {
        rd.start_frame_capture(std::ptr::null(), std::ptr::null());
        // Your rendering code here
        rd.end_frame_capture(std::ptr::null(), std::ptr::null());
    }
}

> We're starting a new Vulkan 1.4 project, which will eventually render sprites, but first lets get the classic triangle up on the screen.

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