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
67 lines
2.1 KiB
HLSL
67 lines
2.1 KiB
HLSL
#pragma once
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#include "Assets/Shaders/Volumetric.cginc"
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float _ExtinctionCoefficient;
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struct RaymarchStatus {
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float3 intensity;
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float depth;
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float depthweightsum;
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float intTransmittance;
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};
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void InitRaymarchStatus(inout RaymarchStatus result){
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result.intTransmittance = 1.0f;
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result.intensity = 0.0f;
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result.depthweightsum = 0.00001f;
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result.depth = 0.0f;
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}
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void IntegrateRaymarch(float3 startPos, float3 rayPos, float fade, float stepsize, inout RaymarchStatus result){
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float4 c = VolumeSampleColor(rayPos);
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float density = c.a;
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if (density <= 0.0f)
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return;
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float extinction = _ExtinctionCoefficient * density / (1-fade);
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float clampedExtinction = max(extinction, 1e-7);
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float transmittance = exp(-extinction * stepsize);
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float3 luminance = c.rgb;
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float3 integScatt = (luminance - luminance * transmittance) / clampedExtinction;
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float depthWeight = result.intTransmittance * (1-transmittance); //Is it a better idead to use (1-transmittance) * intTransmittance as depth weight?
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result.intensity += result.intTransmittance * integScatt;
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result.depth += depthWeight * length(rayPos - startPos);
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result.depthweightsum += depthWeight;
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result.intTransmittance *= transmittance;
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}
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float GetDensity(float3 startPos, float3 dir, float maxSampleDistance, float raymarchOffset, out float3 intensity,out float depth) {
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float raymarchDistance = 0;
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RaymarchStatus result;
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InitRaymarchStatus(result);
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[loop]
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for (int j = 0; j < SAMPLE_COUNT; j++) {
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float prevRayDist = raymarchDistance;
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raymarchDistance = pow((j+raymarchOffset)/SAMPLE_COUNT,2) * _ProjectionParams.z;
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if(raymarchDistance > maxSampleDistance) break;
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float step = raymarchDistance - prevRayDist;
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float3 rayPos = startPos + dir * raymarchDistance;
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float fade = smoothstep(_ProjectionParams.z*.9,_ProjectionParams.z, raymarchDistance);
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IntegrateRaymarch(startPos, rayPos, fade, step, result);
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if (result.intTransmittance < 0.01f) {
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result.intTransmittance = 0;
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break;
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}
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}
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depth = result.depth / result.depthweightsum / _ProjectionParams.z;
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if (depth == 0.0f) {
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depth = maxSampleDistance;
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}
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intensity = result.intensity;
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return (1.0f - result.intTransmittance);
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}
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