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name: vvvv-shaders description: "Helps write SDSL shaders for Stride and vvvv gamma — TextureFX, shader mixins, compute shaders, and ShaderFX composition. SDSL is a superset of HLSL, so use this skill when writing or debugging .sdsl shader files, GPU shaders, visual effects, HLSL code for vvvv, working with the Stride rendering pipeline, composing shader mixins, or any GPU/compute work. Trigger even if the user says 'HLSL', 'shader', 'GPU effect', 'render pass', or 'compute' in a vvvv context." license: CC-BY-SA-4.0 compatibility: Designed for coding AI agents assisting with vvvv gamma development metadata: author: Tebjan Halm version: "1.1"

SDSL Shaders for vvvv gamma / Stride

What Is SDSL

SDSL (Stride Shading Language) is Stride's shader language — a superset of HLSL with four key additions: shader classes with inheritance, multiple inheritance (mixins), the streams system for automatic inter-stage data flow, and override for clean method replacement. Shaders are defined in .sdsl files.

Streams System

Streams replace manual VS_INPUT/VS_OUTPUT structs. Declare once, access everywhere:

stream float4 MyData : TEXCOORD5;      // Declare a custom stream variable

// In vertex shader:
streams.MyData = float4(1, 0, 0, 1);   // Write

// In pixel shader:
float4 d = streams.MyData;             // Read (auto-interpolated)

Key built-in streams:

• streams.ShadingPosition (SV_Position) — clip-space position
• streams.ColorTarget (SV_Target0) — pixel shader output
• streams.Position (float4) — object-space position
• streams.TexCoord (TEXCOORD0) — texture coordinates
• streams.normalWS — world-space normal

Base Shader Hierarchy

Stride Core (available in both Stride and vvvv)

Shader	Provides
ShaderBase	VSMain/PSMain entry points
Texturing	Texture0-9, Sampler, PointSampler, LinearSampler, TexCoord
Transformation	World, View, Projection, WorldViewProjection matrices
PositionStream4	Position, PositionWS, DepthVS
NormalStream	meshNormal, normalWS, tangentToWorld
ComputeShaderBase	CSMain entry, Compute() hook, thread groups
ComputeColor	Interface returning float4 via Compute()
ComputeVoid	Interface returning void via Compute()
Global	Time, TimeStep (cbuffer PerFrame)

vvvv-Only (NOT available in plain Stride)

Shader	Inherits	Use For
VS_PS_Base	ShaderBase, PositionStream4, NormalStream, Transformation	DrawFX base
FilterBase	TextureFX	Pixel-processing texture effects
MixerBase	TextureFX	Blending textures
TextureFX	ImageEffectShader, Camera, ShaderUtils	Texture effect base

Important: VS_PS_Base already includes Transformation, NormalStream, and PositionStream4. Do NOT re-inherit them.

File Naming → Auto Node Generation

vvvv automatically creates nodes from shaders based on filename suffix:

Suffix	Node Type	Description
_TextureFX.sdsl	TextureFX	Image processing effects
_DrawFX.sdsl	DrawFX	Drawing/rendering shaders
_ComputeFX.sdsl	ComputeFX	Compute shaders
_ShaderFX.sdsl	ShaderFX	General shader effects

Example: MyBlur_TextureFX.sdsl automatically creates a "MyBlur" TextureFX node.

Basic TextureFX Structure

shader MyEffect_TextureFX : FilterBase
{
    float Intensity = 1.0;

    float4 Filter(float4 tex0col)
    {
        return tex0col * Intensity;
    }
};

Note the semicolon after the closing brace — this is required.

Syntax Rules

For critical SDSL syntax rules (static const scope, semicolons, override, variable initialization, common mistakes, branch divergence), see syntax-rules.md.

Keywords

Keyword	Purpose
shader	Defines a shader class
override	Required when overriding parent methods
base	Access parent implementation
stage	Ensures member defined once across compositions
stream	Member accessible at every shader stage
static	Static methods callable without inheritance
compose	Declare a composition slot for shader mixins
clone	Force separate instance of a composed shader
abstract	Method without body (child must implement)

Inheritance & Mixins

// Single inheritance
shader Child : Parent
{
    override float4 Filter(float4 tex0col)
    {
        return base.Filter(tex0col) * 0.5;
    }
};

// Multiple inheritance (mixins)
shader MyShader : FilterBase, ColorUtils, MathUtils
{
    float4 Filter(float4 tex0col)
    {
        float3 linear = ColorUtils.GammaToLinear(tex0col.rgb);
        return float4(linear, tex0col.a);
    }
};

// Static function calls (no inheritance needed)
float3 result = ColorUtils.LinearToGamma(col.rgb);

Enum Binding — C# Enum in Shaders

In the shader (.sdsl):

[EnumType("MyNamespace.BlendMode, MyAssembly")]
int Mode = 0;

In C# (.cs):

namespace MyNamespace;
public enum BlendMode
{
    Normal = 0,
    Add = 1,
    Multiply = 2,
    Screen = 3
}

Requirements:

• The enum DLL must be pre-compiled (not from dynamic csproj)
• Assembly name is the project name
• vvvv must be restarted after enum DLL changes

GPU Best Practices

Protect Against Math Errors

float3 safeLog = log2(max(x, 1e-10));     // Avoid log2(0)
float3 safe = x / max(y, 0.0001);          // Avoid div by zero
float3 safePow = pow(max(x, 0.0), gamma);  // Avoid pow(negative)

Texture Sampling

// In TextureFX, tex0col is already sampled from Texture0
float4 Filter(float4 tex0col)
{
    // Sample additional textures:
    float4 tex1 = Texture1.Sample(Texturex1Sampler, streams.TexCoord);
    return lerp(tex0col, tex1, 0.5);
}

ShaderFX / ComputeColor Pattern

Composable shader nodes using compose keyword:

shader MyTonemap_ShaderFX : ComputeColor, TonemapOperators
{
    compose ComputeColor ColorIn;

    [EnumType("MyNamespace.TonemapOp, MyAssembly")]
    int Operator = 1;

    float Exposure = 0.0;

    override float4 Compute()
    {
        float4 color = ColorIn.Compute();
        color.rgb *= exp2(Exposure);
        color.rgb = ApplyTonemap(color.rgb, Operator);
        return color;
    }
};

In vvvv patching, connect a ShaderFX node to a TextureFX's compose input to chain processing.

Mixin Composition — Virtual Method Dispatch

Base shader with a virtual method, overridden by dynamically composed mixins:

// Base shader declares the virtual method
shader ColorProcessorBase
{
    float4 ProcessColor(float4 inPixel) { return inPixel; }
};

// Host shader uses composition
shader ColorTransform_TextureFX : TextureFX
{
    stage compose ColorProcessorBase Processor;

    stage override float4 Shading()
    {
        float4 col = Texture0.SampleLevel(PointSampler, streams.TexCoord, 0);
        return Processor.ProcessColor(col);
    }
};

Template / Generic Shaders

// Declaration with type parameter
shader ComputeColorWave<float Frequency> : ComputeColor, Texturing
{
    override float4 Compute()
    {
        return float4(sin(streams.TexCoord.x * Frequency), 0, 0, 1);
    }
};

// Instantiation via inheritance
shader MyEffect : ComputeColorWave<2.0f> { };

Supported template parameter types: float, int, float2, float3, float4, Texture2D, SamplerState.

Composition Arrays

Multiple composed shaders of the same type:

compose ComputeColor lights[];

override float4 Compute()
{
    float4 total = 0;
    foreach (var light in lights)
        total += light.Compute();
    return total;
}

Shared Struct Types Across Shaders

Define once, use in emit/simulate/draw pipeline:

shader ParticleTypes
{
    struct Particle { float3 Position; float3 Velocity; float Life; };
};

shader Emit_ComputeFX : ComputeShaderBase, ParticleTypes { /* fills buffer */ };
shader Simulate_ComputeFX : ComputeShaderBase, ParticleTypes { /* physics */ };
shader Draw_DrawFX : VS_PS_Base, ParticleTypes { /* renders */ };

For detailed SDSL syntax rules, see syntax-rules.md.