77 lines
No EOL
1.8 KiB
Text
77 lines
No EOL
1.8 KiB
Text
/* Copyright (c) 2025, Sascha Willems
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*
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* SPDX-License-Identifier: MIT
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*
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*/
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struct Particle
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{
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float4 pos;
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float4 vel;
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};
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// Binding 0 : Position storage buffer
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RWStructuredBuffer<Particle> particles;
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struct UBO
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{
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float deltaT;
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int particleCount;
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float gravity;
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float power;
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float soften;
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};
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ConstantBuffer<UBO> ubo;
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#define MAX_SHARED_DATA_SIZE 1024
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[[SpecializationConstant]] const int SHARED_DATA_SIZE = 512;
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[[SpecializationConstant]] const float GRAVITY = 0.002;
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[[SpecializationConstant]] const float POWER = 0.75;
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[[SpecializationConstant]] const float SOFTEN = 0.0075;
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// Share data between computer shader invocations to speed up caluclations
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groupshared float4 sharedData[MAX_SHARED_DATA_SIZE];
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[shader("compute")]
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[numthreads(256, 1, 1)]
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void computeMain(uint3 GlobalInvocationID : SV_DispatchThreadID, uint3 LocalInvocationID : SV_GroupThreadID)
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{
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// Current SSBO index
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uint index = GlobalInvocationID.x;
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if (index >= ubo.particleCount)
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return;
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float4 position = particles[index].pos;
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float4 velocity = particles[index].vel;
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float4 acceleration = float4(0, 0, 0, 0);
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for (int i = 0; i < ubo.particleCount; i += SHARED_DATA_SIZE)
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{
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if (i + LocalInvocationID.x < ubo.particleCount)
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{
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sharedData[LocalInvocationID.x] = particles[i + LocalInvocationID.x].pos;
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}
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else
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{
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sharedData[LocalInvocationID.x] = float4(0, 0, 0, 0);
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}
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GroupMemoryBarrierWithGroupSync();
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for (int j = 0; j < 256; j++)
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{
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float4 other = sharedData[j];
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float3 len = other.xyz - position.xyz;
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acceleration.xyz += ubo.gravity * len * other.w / pow(dot(len, len) + ubo.soften, ubo.power);
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}
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GroupMemoryBarrierWithGroupSync();
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}
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particles[index].vel.xyz += ubo.deltaT * acceleration.xyz;
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// Gradient texture position
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particles[index].vel.w += 0.1 * ubo.deltaT;
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if (particles[index].vel.w > 1.0) {
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particles[index].vel.w -= 1.0;
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}
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} |