procedural-3d-engine/shaders/slang/tessellation/passthrough.slang
2025-05-16 20:12:30 +02:00

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/* Copyright (c) 2025, Sascha Willems
*
* SPDX-License-Identifier: MIT
*
*/
struct VSOutput
{
float4 Pos : SV_POSITION;
float3 Normal;
float2 UV;
};
struct HSOutput
{
float4 Pos : SV_POSITION;
float3 Normal;
float2 UV;
};
struct DSOutput
{
float4 Pos : SV_POSITION;
float3 Normal;
float2 UV;
};
struct ConstantsHSOutput
{
float TessLevelOuter[3] : SV_TessFactor;
float TessLevelInner[2] : SV_InsideTessFactor;
};
struct UBO
{
float4x4 projection;
float4x4 model;
float tessAlpha;
float tessLevel;
};
ConstantBuffer<UBO> ubo;
ConstantsHSOutput ConstantsHS(InputPatch<VSOutput, 3> patch)
{
ConstantsHSOutput output;
output.TessLevelInner[0] = 1;
output.TessLevelInner[1] = 1;
output.TessLevelOuter[0] = 1;
output.TessLevelOuter[1] = 1;
output.TessLevelOuter[2] = 1;
return output;
}
[shader("hull")]
[domain("tri")]
[partitioning("integer")]
[outputtopology("triangle_cw")]
[outputcontrolpoints(3)]
[patchconstantfunc("ConstantsHS")]
[maxtessfactor(20.0f)]
HSOutput hullMain(InputPatch<VSOutput, 3> patch, uint InvocationID : SV_OutputControlPointID)
{
HSOutput output;
output.Pos = patch[InvocationID].Pos;
output.Normal = patch[InvocationID].Normal;
output.UV = patch[InvocationID].UV;
return output;
}
[shader("domain")]
[domain("tri")]
DSOutput domainMain(ConstantsHSOutput input, float3 TessCoord: SV_DomainLocation, const OutputPatch<HSOutput, 3> patch)
{
DSOutput output = (DSOutput)0;
output.Pos = (TessCoord.x * patch[0].Pos) +
(TessCoord.y * patch[1].Pos) +
(TessCoord.z * patch[2].Pos);
output.Pos = mul(ubo.projection, mul(ubo.model, output.Pos));
output.Normal = TessCoord.x * patch[0].Normal + TessCoord.y * patch[1].Normal + TessCoord.z * patch[2].Normal;
output.UV = TessCoord.x * patch[0].UV + TessCoord.y * patch[1].UV + TessCoord.z * patch[2].UV;
return output;
}