ShaderGen

A proof-of-concept library which generates shader code from C#. Currently, the project can generate HLSL (D3D11), GLSL-330 (core-GL-compatible), GLSLES-300 (OpenGL ES-compatible), GLSL-450 (Vulkan-compatible), and Metal shader code from a single shader source specified in C#.

Shaders in C#

Writing shader code in C# could have quite a few benefits:

• Easily share type definitions between graphics code in C# and shaders.
  • For example, one could re-use the same structure to describe the input to a vertex shader, as well as to store the actual vertex data in your C# program.
  • Shader uniforms ("constant buffers") can be shared as well.
• Analysis done at code-generation time can be used to build extra metadata about the shaders, enabling reflection-like capabilities.
  • The full vertex input specification can be generated when doing the C# analysis for code generation.
  • The layouts and order for all global shader resources can be captured.
  • Validation can be performed to ensure, for example, uniforms are multiples of 16-bytes in size, etc.
• C# refactoring tools can be used.
• C# niceties like inheritance, composition, partial declarations, etc. can be leveraged for easier shader writing (speculative).

Example Shader

Here is an example vertex and fragment shader, written in C# with ShaderGen:

public class MinExample
{
    public Matrix4x4 Projection;
    public Matrix4x4 View;
    public Matrix4x4 World;
    public Texture2DResource SurfaceTexture;
    public SamplerResource Sampler;

    public struct VertexInput
    {
        [PositionSemantic] public Vector3 Position;
        [TextureCoordinateSemantic] public Vector2 TextureCoord;
    }

    public struct FragmentInput
    {
        [SystemPositionSemanticAttribute] public Vector4 Position;
        [TextureCoordinateSemantic] public Vector2 TextureCoord;
    }

    [VertexShader]
    public FragmentInput VertexShaderFunc(VertexInput input)
    {
        FragmentInput output;
        Vector4 worldPosition = Mul(World, new Vector4(input.Position, 1));
        Vector4 viewPosition = Mul(View, worldPosition);
        output.Position = Mul(Projection, viewPosition);
        output.TextureCoord = input.TextureCoord;
        return output;
    }

    [FragmentShader]
    public Vector4 FragmentShaderFunc(FragmentInput input)
    {
        return Sample(SurfaceTexture, Sampler, input.TextureCoord);
    }
}

Here is some representative output from the library (subject to change, etc.):

HLSL Vertex Shader

struct MinExample_VertexInput
{
    float3 Position : POSITION0;
    float2 TextureCoord : TEXCOORD0;
};

struct MinExample_FragmentInput
{
    float4 Position : SV_Position;
    float2 TextureCoord : TEXCOORD0;
};

cbuffer ProjectionBuffer : register(b0)
{
    float4x4 Projection;
}

cbuffer ViewBuffer : register(b1)
{
    float4x4 View;
}

cbuffer WorldBuffer : register(b2)
{
    float4x4 World;
}

MinExample_FragmentInput VertexShaderFunc( MinExample_VertexInput input)
{
    MinExample_FragmentInput output;
    float4 worldPosition = mul(World, float4(input.Position, 1));
    float4 viewPosition = mul(View, worldPosition);
    output.Position = mul(Projection, viewPosition);
    output.TextureCoord = input.TextureCoord;
    return output;
}

HLSL Fragment Shader

struct MinExample_VertexInput
{
    float3 Position : POSITION0;
    float2 TextureCoord : TEXCOORD0;
};

struct MinExample_FragmentInput
{
    float4 Position : SV_Position;
    float2 TextureCoord : TEXCOORD0;
};

Texture2D SurfaceTexture : register(t0);

SamplerState Sampler : register(s0);

float4 FragmentShaderFunc( MinExample_FragmentInput input) : SV_Target
{
    return SurfaceTexture.Sample(Sampler, input.TextureCoord);
}

GLSL (450) Vertex Shader

#version 450
#extension GL_ARB_separate_shader_objects : enable
#extension GL_ARB_shading_language_420pack : enable
struct MinExample_VertexInput
{
    vec3 Position;
    vec2 TextureCoord;
};

struct MinExample_FragmentInput
{
    vec4 Position;
    vec2 TextureCoord;
};

layout(set = 0, binding = 0) uniform Projection
{
    mat4 field_Projection;
};

layout(set = 0, binding = 1) uniform View
{
    mat4 field_View;
};

layout(set = 0, binding = 2) uniform World
{
    mat4 field_World;
};

layout(set = 0, binding = 3) uniform texture2D SurfaceTexture;
layout(set = 0, binding = 4) uniform sampler Sampler;
MinExample_FragmentInput VertexShaderFunc( MinExample_VertexInput input_)
{
    MinExample_FragmentInput output_;
    vec4 worldPosition = field_World * vec4(input_.Position, 1);
    vec4 viewPosition = field_View * worldPosition;
    output_.Position = field_Projection * viewPosition;
    output_.TextureCoord = input_.TextureCoord;
    return output_;
}


layout(location = 0) in vec3 Position;
layout(location = 1) in vec2 TextureCoord;
layout(location = 0) out vec2 fsin_0;

void main()
{
    MinExample_VertexInput input_;
    input_.Position = Position;
    input_.TextureCoord = TextureCoord;
    MinExample_FragmentInput output_ = VertexShaderFunc(input_);
    fsin_0 = output_.TextureCoord;
    gl_Position = output_.Position;
        gl_Position.y = -gl_Position.y; // Correct for Vulkan clip coordinates
}

GLSL (450) Fragment Shader

#version 450
#extension GL_ARB_separate_shader_objects : enable
#extension GL_ARB_shading_language_420pack : enable
struct MinExample_VertexInput
{
    vec3 Position;
    vec2 TextureCoord;
};

struct MinExample_FragmentInput
{
    vec4 Position;
    vec2 TextureCoord;
};

layout(set = 0, binding = 0) uniform Projection
{
    mat4 field_Projection;
};

layout(set = 0, binding = 1) uniform View
{
    mat4 field_View;
};

layout(set = 0, binding = 2) uniform World
{
    mat4 field_World;
};

layout(set = 0, binding = 3) uniform texture2D SurfaceTexture;
layout(set = 0, binding = 4) uniform sampler Sampler;
vec4 FragmentShaderFunc( MinExample_FragmentInput input_)
{
    return texture(sampler2D(SurfaceTexture, Sampler), input_.TextureCoord);
}


layout(location = 0) in vec2 fsin_0;
layout(location = 0) out vec4 _outputColor_;

void main()
{
    MinExample_FragmentInput input_;
    input_.Position = gl_FragCoord;
    input_.TextureCoord = fsin_0;
    vec4 output_ = FragmentShaderFunc(input_);
    _outputColor_ = output_;
}