wehub-resource-sync
117 lines
3.2 KiB
HLSL
117 lines
3.2 KiB
HLSL
#include "shared/point.hlsl"
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#include "shared/quat-functions.hlsl"
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RWStructuredBuffer<Particle> particles :register(u0);
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cbuffer Params : register(b0)
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{
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float CellSize;
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float Bounciness;
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float Attraction;
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float SpeedFactor;
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float AttractionDecay;
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float CollisionResolve;
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}
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#include "points/spatial-hash-map/spatial-hash-map-lookup.hlsl"
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static const float3 CellOffsets[] =
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{
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float3(0,0,0) - 0.5,
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float3(0,0,1) - 0.5,
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float3(0,1,0) - 0.5,
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float3(0,1,1) - 0.5,
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float3(1,0,0) - 0.5,
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float3(1,0,1) - 0.5,
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float3(1,1,0) - 0.5,
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float3(1,1,1) - 0.5,
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};
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[numthreads( 16, 1, 1 )]
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void DispersePoints(uint3 DTid : SV_DispatchThreadID, uint GI: SV_GroupIndex)
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{
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uint gi = DTid.x;
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uint pointCount, stride;
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particles.GetDimensions(pointCount, stride);
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if(gi >= pointCount)
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return; // out of bounds
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Particle p = particles[gi];
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float3 position = p.Position;
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uint startIndex, endIndex;
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int closestIndex = -1;
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float3 closestDirection = 0;
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float closestDistance = 9999999;
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float3 forceSum =0;
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int count = 0;
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float3 pos = particles[gi].Position;
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float3 velocity = particles[gi].Velocity;
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float3 posNext = pos + velocity * SpeedFactor * 0.01;
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float r = particles[gi].Radius;
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for(int cellOffsetIndex =0; cellOffsetIndex < 8; cellOffsetIndex++)
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{
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float3 cellOffset = CellOffsets[cellOffsetIndex] * CellSize;
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if(GridFind(position + cellOffset, startIndex, endIndex))
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{
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const uint particleCount = endIndex - startIndex;
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float3 sumForces = 0;
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endIndex = min(startIndex + 64 , endIndex);
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for(uint i=startIndex; i < endIndex; ++i)
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{
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uint otherIndex = CellPointIndices[i];
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if( otherIndex == gi)
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continue;
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float3 otherPos = particles[otherIndex].Position;
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float r2 = particles[otherIndex].Radius;
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float3 pToO = pos - otherPos;
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float centerDistance = length(pToO);
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if(centerDistance < 0.0001)
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{
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pToO = hash41u(gi).xyz * float3(1,1,0) * 0.01;
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centerDistance = length(pToO);
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}
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float3 direction = pToO / centerDistance;
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float gap = centerDistance - r2 - r;
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float gapNext = length(posNext - otherPos) - r2 - r;
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float massRatio = (r) / (r2);
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if(sign( gap * gapNext) < 0 && gap > 0)
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{
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velocity = reflect(velocity, direction );
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particles[gi].Velocity = velocity * Bounciness;
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}
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else
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{
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// Already inside...
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if(gap < 0)
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{
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particles[gi].Position -= direction * gap * CollisionResolve;
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}
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// Attraction?
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else
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{
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particles[gi].Velocity -= (direction * Attraction / massRatio) * (1/( pow(centerDistance, AttractionDecay))) ;
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}
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}
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}
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}
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}
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} |