Problem

GPU constant buffers (cbuffer structures) in HLSL must be aligned to 16-byte boundaries for optimal performance and correctness. Currently, the project relies on manual padding (e.g., uint b0pad0[2] in ClusterBuildingCS.hlsl) to ensure proper alignment, but this approach is error-prone and lacks compile-time validation.

Current State

The codebase contains various cbuffer structures across shader files that use manual padding:

cbuffer PerFrame : register(b0)
{
    float LightsNear;
    float LightsFar;
    uint b0pad0[2];  // Manual padding for alignment
}

Some settings may be combined from multiple features into a single cbuffer so misalignment may break later feature settings.

Goal

Implement a system that provides compile-time validation to ensure all GPU buffers maintain proper 16-byte alignment without relying solely on manual padding techniques.

Requirements

• Detect misaligned buffer structures at compile time
• Work with existing HLSL cbuffer declarations
• Minimize impact on current shader code
• Provide clear error messages when alignment issues are detected
• Consider compatibility with DirectX shader compilation pipeline
• Should be automatic or otherwise easy for developers to add

Context

This issue stems from PR #542 which attempted to add static asserts for buffer alignment. However, the solution should not be limited to static asserts and should explore various approaches to solve the compile-time alignment validation problem.

Related

• Original PR: chore: add static-assert for GPU buffers #542
• Comment: chore: add static-assert for GPU buffers #542 (comment)

/cc @alandtse