procedural-3d-engine/shaders/hlsl/tessellation/pntriangles.tesc
2024-01-14 10:24:55 +01:00

131 lines
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3.5 KiB
GLSL

// Copyright 2020 Google LLC
// PN patch data
struct PnPatch
{
float b210;
float b120;
float b021;
float b012;
float b102;
float b201;
float b111;
float n110;
float n011;
float n101;
};
// tessellation levels
struct UBO
{
float4x4 projection;
float4x4 model;
float tessAlpha;
float tessLevel;
};
cbuffer ubo : register(b0) { UBO ubo; }
struct VSOutput
{
float4 Pos : SV_POSITION;
[[vk::location(0)]] float3 Normal : NORMAL0;
[[vk::location(1)]] float2 UV : TEXCOORD0;
};
struct HSOutput
{
float4 Pos : SV_POSITION;
[[vk::location(0)]] float3 Normal : NORMAL0;
[[vk::location(3)]] float2 UV : TEXCOORD0;
[[vk::location(6)]] float pnPatch[10] : TEXCOORD6;
};
struct ConstantsHSOutput
{
float TessLevelOuter[3] : SV_TessFactor;
float TessLevelInner : SV_InsideTessFactor;
};
void SetPnPatch(out float output[10], PnPatch patch)
{
output[0] = patch.b210;
output[1] = patch.b120;
output[2] = patch.b021;
output[3] = patch.b012;
output[4] = patch.b102;
output[5] = patch.b201;
output[6] = patch.b111;
output[7] = patch.n110;
output[8] = patch.n011;
output[9] = patch.n101;
}
float wij(float4 iPos, float3 iNormal, float4 jPos)
{
return dot(jPos.xyz - iPos.xyz, iNormal);
}
float vij(float4 iPos, float3 iNormal, float4 jPos, float3 jNormal)
{
float3 Pj_minus_Pi = jPos.xyz
- iPos.xyz;
float3 Ni_plus_Nj = iNormal+jNormal;
return 2.0*dot(Pj_minus_Pi, Ni_plus_Nj)/dot(Pj_minus_Pi, Pj_minus_Pi);
}
ConstantsHSOutput ConstantsHS(InputPatch<VSOutput, 3> patch, uint InvocationID : SV_PrimitiveID)
{
ConstantsHSOutput output = (ConstantsHSOutput)0;
output.TessLevelOuter[0] = ubo.tessLevel;
output.TessLevelOuter[1] = ubo.tessLevel;
output.TessLevelOuter[2] = ubo.tessLevel;
output.TessLevelInner = ubo.tessLevel;
return output;
}
[domain("tri")]
[partitioning("fractional_odd")]
[outputtopology("triangle_cw")]
[outputcontrolpoints(3)]
[patchconstantfunc("ConstantsHS")]
[maxtessfactor(20.0f)]
HSOutput main(InputPatch<VSOutput, 3> patch, uint InvocationID : SV_OutputControlPointID)
{
HSOutput output = (HSOutput)0;
// get data
output.Pos = patch[InvocationID].Pos;
output.Normal = patch[InvocationID].Normal;
output.UV = patch[InvocationID].UV;
// set base
float P0 = patch[0].Pos[InvocationID];
float P1 = patch[1].Pos[InvocationID];
float P2 = patch[2].Pos[InvocationID];
float N0 = patch[0].Normal[InvocationID];
float N1 = patch[1].Normal[InvocationID];
float N2 = patch[2].Normal[InvocationID];
// compute control points
PnPatch pnPatch;
pnPatch.b210 = (2.0*P0 + P1 - wij(patch[0].Pos, patch[0].Normal, patch[1].Pos)*N0)/3.0;
pnPatch.b120 = (2.0*P1 + P0 - wij(patch[1].Pos, patch[1].Normal, patch[0].Pos)*N1)/3.0;
pnPatch.b021 = (2.0*P1 + P2 - wij(patch[1].Pos, patch[1].Normal, patch[2].Pos)*N1)/3.0;
pnPatch.b012 = (2.0*P2 + P1 - wij(patch[2].Pos, patch[2].Normal, patch[1].Pos)*N2)/3.0;
pnPatch.b102 = (2.0*P2 + P0 - wij(patch[2].Pos, patch[2].Normal, patch[0].Pos)*N2)/3.0;
pnPatch.b201 = (2.0*P0 + P2 - wij(patch[0].Pos, patch[0].Normal, patch[2].Pos)*N0)/3.0;
float E = ( pnPatch.b210
+ pnPatch.b120
+ pnPatch.b021
+ pnPatch.b012
+ pnPatch.b102
+ pnPatch.b201 ) / 6.0;
float V = (P0 + P1 + P2)/3.0;
pnPatch.b111 = E + (E - V)*0.5;
pnPatch.n110 = N0+N1-vij(patch[0].Pos, patch[0].Normal, patch[1].Pos, patch[1].Normal)*(P1-P0);
pnPatch.n011 = N1+N2-vij(patch[1].Pos, patch[1].Normal, patch[2].Pos, patch[2].Normal)*(P2-P1);
pnPatch.n101 = N2+N0-vij(patch[2].Pos, patch[2].Normal, patch[0].Pos, patch[0].Normal)*(P0-P2);
SetPnPatch(output.pnPatch, pnPatch);
return output;
}