Caio Raphael

WGSL (WebGPU)

Modern, safe, and cross-platform (WebGPU standard).
Works in browsers (WebGPU) and native (via wgpu ).
No corporate lock-in (developed by W3C & Mozilla/Google/Apple).
Newer, less mature than GLSL/SPIR-V.
"Explicitly designed to avoid C++/OOP cruft. Rust-inspired syntax but purely for GPU work."

~HLSL (High-level Shader Language)

HLSL .
Proprietary to Microsoft.
Made for DirectX 9.
HLSL programs come in six forms: pixel shaders (fragment in GLSL), vertex shaders, geometry shaders, compute shaders, tessellation shaders (Hull and Domain shaders), and ray tracing shaders.
Where it can be used :
- Is mainly used in DirectX-based environments (Windows/Xbox games, Unity, Unreal Engine). If you're targeting other platforms (macOS, Linux, mobile), you might need to use GLSL, MSL, or SPIR-V instead.
- Direct3D (DirectX)
  - DirectX 9/10/11/12: HLSL is the standard shading language for Microsoft's Direct3D API.
  - Used in:
    - PC games (Windows)
    - Xbox console development (Xbox One, Xbox Series XS)
- Unity (via Direct3D)
  - Unity supports HLSL when using:
    - Built-in Render Pipeline (Legacy)
    - Universal Render Pipeline (URP)
    - High Definition Render Pipeline (HDRP)
  - Shader Graph in Unity also uses HLSL-like syntax.
- Unreal Engine (UE4/UE5)
  - Unreal Engine uses a custom shading language (Unreal Shader System, USS) but allows HLSL snippets in Custom HLSL Nodes.
  - HLSL is also used in Ray Tracing shaders in UE5.
- NVIDIA OptiX (Ray Tracing)
  - HLSL can sometimes be used alongside CUDA/PTX for ray tracing effects.
- Vulkan (via SPIR-V Cross)
  - HLSL shaders can be converted to SPIR-V (Vulkan's intermediate format) using tools like:
    - glslangValidator (from Khronos)
    - DXC (DirectX Shader Compiler)
    - SPIRV-Cross (converts HLSL to GLSL/SPIR-V)
- Shader Model 6.0+ (Advanced Features)
  - HLSL supports modern GPU features like:
    - Ray Tracing (DXR)
    - Mesh & Amplification Shaders
    - Wave Operations.
- Compute Shaders
  - (GPGPU programming in DirectX).
- AI/ML Acceleration
  - (Some frameworks allow HLSL-based compute shaders for GPU acceleration).
Where it's not used :
- OpenGL / WebGL → Uses GLSL instead.
- Vulkan (Native) → Uses GLSL or SPIR-V.
- Metal (Apple) → Uses MSL (Metal Shading Language).

Ex :

// Vertex Shader
struct VSInput {
    float3 position : POSITION;
    float3 color : COLOR;
};

struct VSOutput {
    float4 position : SV_POSITION;
    float3 color : COLOR;
};

VSOutput VS_main(VSInput input) {
    VSOutput output;
    output.position = float4(input.position, 1.0);
    output.color = input.color;
    return output;
}

// Fragment Shader
struct PSInput {
    float4 position : SV_POSITION;
    float3 color : COLOR;
};

float4 PS_main(PSInput input) : SV_TARGET {
    return float4(input.color, 1.0);
}

Comparing the syntax of HLSL to GLSL :
- Inputs :
  - HLSL:
    - The parameter for the VS_main and PS_main describe the inputs for each step.
    - Uses a struct with semantics ( : POSITION , : COLOR ).
  - GLSL:
    - Uses in / out variables.
    - Uses layout(location) to bind vertex attributes.
- Outputs :
  - HLSL:
    Returns a struct, for passing values from the Vertex Shader to the Fragment Shader; VSOutput .
  - GLSL:
    - Uses a out variable.

MSL (Metal Shading Language)

Apple’s official shader language (optimized for M1/M2).
Required for iOS/macOS Metal apps.
Apple-only (no Windows/Linux).
Use with MoltenVK if you want Vulkan → Metal compatibility.

Ex :

// Vertex Shader
#include <metal_stdlib>
using namespace metal;

struct VertexIn {
    float3 position [[attribute(0)]];
    float3 color [[attribute(1)]];
};

struct VertexOut {
    float4 position [[position.md]];
    float3 color;
};

vertex VertexOut vertex_main(VertexIn in [[stage_in]]) {
    VertexOut out;
    out.position = float4(in.position, 1.0);
    out.color = in.color;
    return out;
}

// Fragment Shader
fragment float4 fragment_main(VertexOut in [[stage_in]]) {
    return float4(in.color, 1.0);
}

SPIR-V

GLSL (OpenGL Shader Language)

Slang

WGSL (WebGPU)

~HLSL (High-level Shader Language)

MSL (Metal Shading Language)