be5e7618d6
Improved volumetric flow performance by orders of magnitude Cleaned up old raymarching support code Moved asteroid height calculation to vertex shader Manual culling for asteroid field render update
150 lines
No EOL
3.6 KiB
Text
150 lines
No EOL
3.6 KiB
Text
// Based on https://github.com/keijiro/StableFluids
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#include "Assets/Shaders/Volumetric.cginc"
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#pragma kernel Advect
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#pragma kernel Force
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#pragma kernel PSetup
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#pragma kernel PFinish
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#pragma kernel Jacobi1
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#pragma kernel Jacobi2
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#pragma kernel Adjust
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// Common parameter
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float Time;
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float DeltaTime;
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// Adjustment
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int2 Delta;
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float Damping;
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// External force
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float2 ForceOrigin;
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float2 ForceVector;
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float ForceExponent;
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// U (velocity field)
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Texture2D<float2> U_in;
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SamplerState samplerU_in;
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RWTexture2D<float2> U_out;
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// W (velocity field; working)
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Texture2D<float2> W_in;
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RWTexture2D<float2> W_out;
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// Div W
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RWTexture2D<float> DivW_out;
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// P (pressure field)
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Texture2D<float> P_in;
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RWTexture2D<float> P_out;
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// Color map
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Texture2D<half4> C_in;
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SamplerState samplerC_in;
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RWTexture2D<half4> C_out;
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// Jacobi method arguments
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float Alpha, Beta;
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Texture2D<float> X1_in;
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Texture2D<float> B1_in;
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RWTexture2D<float> X1_out;
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Texture2D<float2> X2_in;
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Texture2D<float2> B2_in;
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RWTexture2D<float2> X2_out;
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// Advect step
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[numthreads(8, 8, 1)]
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void Advect(uint2 tid : SV_DispatchThreadID)
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{
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uint2 dim;
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W_out.GetDimensions(dim.x, dim.y);
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float2 uv = (tid + 0.5) / dim;
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float2 duv = U_in[tid] * float2((float)dim.y / dim.x, 1) * DeltaTime;
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W_out[tid] = U_in.SampleLevel(samplerU_in, uv - duv, 0);
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}
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// Add-force step
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[numthreads(8, 8, 1)]
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void Force(uint2 tid : SV_DispatchThreadID)
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{
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uint2 dim;
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W_out.GetDimensions(dim.x, dim.y);
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float2 pos = (tid + 0.5) / dim.y;
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float amp = exp(-ForceExponent * distance(ForceOrigin, pos));
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W_out[tid] = W_in[tid] + ForceVector * amp;
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}
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// Setup for Project step (divW calculation)
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[numthreads(8, 8, 1)]
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void PSetup(uint2 tid : SV_DispatchThreadID)
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{
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uint2 dim;
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W_in.GetDimensions(dim.x, dim.y);
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DivW_out[tid] = (W_in[tid + int2(1, 0)].x - W_in[tid - int2(1, 0)].x +
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W_in[tid + int2(0, 1)].y - W_in[tid - int2(0, 1)].y) * dim.y / 2;
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P_out[tid] = 0;
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}
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// Finishing for Project step (divergence free field calculation)
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[numthreads(8, 8, 1)]
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void PFinish(uint2 tid : SV_DispatchThreadID)
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{
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uint2 dim;
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W_in.GetDimensions(dim.x, dim.y);
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if (any(tid == 0) || any(tid == dim - 1)) return;
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float P1 = P_in[max(tid - int2(1, 0), 1)];
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float P2 = P_in[min(tid + int2(1, 0), dim - 2)];
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float P3 = P_in[max(tid - int2(0, 1), 1)];
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float P4 = P_in[min(tid + int2(0, 1), dim - 2)];
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float2 u = W_in[tid] - float2(P2 - P1, P4 - P3) * dim.y / 2;
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U_out[tid] = u;
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if (tid.x == 1) U_out[int2(0, tid.y)] = -u;
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if (tid.y == 1) U_out[int2(tid.x, 0)] = -u;
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if (tid.x == dim.x - 2) U_out[int2(dim.x - 1, tid.y)] = -u;
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if (tid.y == dim.y - 2) U_out[int2(tid.x, dim.y - 1)] = -u;
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}
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// Jacobi method with a scalar field
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[numthreads(8, 8, 1)]
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void Jacobi1(uint2 tid : SV_DispatchThreadID)
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{
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X1_out[tid] = (X1_in[tid - int2(1, 0)] + X1_in[tid + int2(1, 0)] +
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X1_in[tid - int2(0, 1)] + X1_in[tid + int2(0, 1)] + Alpha * B1_in[tid]) / Beta;
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}
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// Jacobi method with a vector field
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[numthreads(8, 8, 1)]
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void Jacobi2(uint2 tid : SV_DispatchThreadID)
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{
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X2_out[tid] = (X2_in[tid - int2(1, 0)] + X2_in[tid + int2(1, 0)] +
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X2_in[tid - int2(0, 1)] + X2_in[tid + int2(0, 1)] + Alpha * B2_in[tid]) / Beta;
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}
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// Adjust step (translate & fade towards global velocity field)
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[numthreads(8, 8, 1)]
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void Adjust(uint2 tid : SV_DispatchThreadID)
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{
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uint2 dim;
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W_out.GetDimensions(dim.x, dim.y);
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float2 uv = (tid + float2(.5,.5)) / dim;
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float2 prevUV = uv - Delta;
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if(any(prevUV<0)||any(prevUV>1))
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W_out[tid] = 0;
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else W_out[tid] = U_in.SampleLevel(samplerU_in, prevUV, 0);
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} |