64 lines
1.6 KiB
Plaintext
64 lines
1.6 KiB
Plaintext
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#pragma kernel Project
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#pragma kernel Apply
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#include "MathUtils.cginc"
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#include "AtomicDeltas.cginc"
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StructuredBuffer<int> particleIndices;
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StructuredBuffer<float> stiffnesses;
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RWStructuredBuffer<float> lambdas;
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RWStructuredBuffer<float4> positions;
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StructuredBuffer<float> invMasses;
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// Variables set from the CPU
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uint activeConstraintCount;
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float deltaTime;
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float sorFactor;
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[numthreads(128, 1, 1)]
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void Project (uint3 id : SV_DispatchThreadID)
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{
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unsigned int i = id.x;
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if (i >= activeConstraintCount) return;
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int p1 = particleIndices[i * 2];
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int p2 = particleIndices[i * 2 + 1];
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float w1 = invMasses[p1];
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float w2 = invMasses[p2];
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// calculate time adjusted compliance
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float compliance = stiffnesses[i] / (deltaTime * deltaTime);
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// calculate position and lambda deltas:
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float4 dist = positions[p1] - positions[p2];
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float constraint = length(dist);
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// calculate lambda and position deltas:
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float dlambda = (-constraint - compliance * lambdas[i]) / (w1 + w2 + compliance + EPSILON);
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float4 delta = dlambda * dist / (constraint + EPSILON);
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lambdas[i] += dlambda;
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float4 delta1 = delta * w1;
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float4 delta2 = -delta * w2;
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AddPositionDelta(p1, delta1);
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AddPositionDelta(p2, delta2);
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}
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[numthreads(128, 1, 1)]
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void Apply (uint3 id : SV_DispatchThreadID)
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{
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unsigned int i = id.x;
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if (i >= activeConstraintCount) return;
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int p1 = particleIndices[i * 2];
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int p2 = particleIndices[i * 2 + 1];
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ApplyPositionDelta(positions, p1, sorFactor);
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ApplyPositionDelta(positions, p2, sorFactor);
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}
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