public override void GenerateShader(MaterialGeneratorContext context)
{
if (DisplacementMap == null)
{
return;
}
var materialStage = (MaterialShaderStage)Stage;
// reset the displacement streams at the beginning of the stage
context.AddStreamInitializer(materialStage, "MaterialDisplacementStream");
// set the blending mode of displacement map to additive (and not default linear blending)
context.UseStreamWithCustomBlend(materialStage, DisplacementStream, new ShaderClassSource("MaterialStreamAdditiveBlend", DisplacementStream));
// build the displacement computer
var displacement = DisplacementMap;
if (ScaleAndBias) // scale and bias should be done by layer
{
displacement = new ComputeBinaryScalar(displacement, new ComputeFloat(2f), BinaryOperator.Multiply);
displacement = new ComputeBinaryScalar(displacement, new ComputeFloat(1f), BinaryOperator.Subtract);
}
displacement = new ComputeBinaryScalar(displacement, Intensity, BinaryOperator.Multiply);
// Workaround to inform compute colors that sampling is occurring from a vertex shader
context.IsNotPixelStage = materialStage != MaterialShaderStage.Pixel;
context.SetStream(materialStage, DisplacementStream, displacement, MaterialKeys.DisplacementMap, MaterialKeys.DisplacementValue);
context.IsNotPixelStage = false;
var scaleNormal = materialStage != MaterialShaderStage.Vertex;
var positionMember = materialStage == MaterialShaderStage.Vertex ? "Position" : "PositionWS";
var normalMember = materialStage == MaterialShaderStage.Vertex ? "meshNormal" : "normalWS";
context.SetStreamFinalModifier <MaterialDisplacementMapFeature>(materialStage, new ShaderClassSource("MaterialSurfaceDisplacement", positionMember, normalMember, scaleNormal));
}