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Improved soft shadows.

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This commit is contained in:
Pieter-Jan Briers
2021-04-19 01:42:59 +02:00
parent 70f82d6db8
commit 7aecdcf70a
1 changed files with 52 additions and 12 deletions
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64
Resources/Shaders/Internal/light-soft.swsl
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@@ -1,5 +1,11 @@
#include "/Shaders/Internal/light_shared.swsl"
highp vec4 calcGaussianWeights(highp float sigma, highp vec4 offset)
{
highp vec4 eExp = offset * offset / (2.0 * sigma * sigma);
return exp(-eExp) / (sigma * sqrt(2.0 * PI));
}
highp float createOcclusion(highp vec2 diff)
{
// Calculate vector perpendicular to light vector.
@@ -8,23 +14,57 @@ highp float createOcclusion(highp vec2 diff)
highp float ourDist = length(diff);
highp vec2 occlDist = occludeDepth(diff, shadowMap, lightIndex);
// Sample 7 points on a line perpendicular to the light source.
// Depending on the closest point, we change the gaussian weights down below
// to change the "narrowness" of the samples.
perpendicular *= lightSoftness * 1.5;
// Get all the samples we need.
highp vec2 sample1 = occludeDepth(diff, shadowMap, lightIndex);
highp vec2 sample2 = occludeDepth(diff + perpendicular, shadowMap, lightIndex);
highp vec2 sample3 = occludeDepth(diff - perpendicular, shadowMap, lightIndex);
highp vec2 sample4 = occludeDepth(diff + perpendicular * 2.0, shadowMap, lightIndex);
highp vec2 sample5 = occludeDepth(diff - perpendicular * 2.0, shadowMap, lightIndex);
highp vec2 sample6 = occludeDepth(diff + perpendicular * 3.0, shadowMap, lightIndex);
highp vec2 sample7 = occludeDepth(diff - perpendicular * 3.0, shadowMap, lightIndex);
highp float mindist =
min(sample1.x,
min(sample2.x,
min(sample3.x,
min(sample4.x,
min(sample5.x,
min(sample6.x,
sample7.x))))));
mindist = max(0.001, mindist);
// Change soft shadow size based on distance from primary occluder.
highp float distRatio = (ourDist - occlDist.x) / occlDist.x / 2.0;
highp float distRatio = (ourDist - mindist);
perpendicular *= distRatio * lightSoftness;
// Sigma can never be zero so make sure to clamp.
// TODO: Scaling the dist ratio here in a more sane way might make shadows look better buuuut I'm lazy.
// Shadows look pretty nice already.
highp float sigma = max(0.001, distRatio * 0.75);
highp vec4 weights = calcGaussianWeights(sigma, vec4(0.0, 1.0, 2.0, 3.0));
// Totally not hacky PCF on top of VSM.
highp float occlusion = smoothstep(0.1, 1.0, ChebyshevUpperBound(occlDist, ourDist));
// Calculation of gaussian weights here is broken because it doesn't add up to 1.
// Fixing this is hard and if I had to guess too expensive for GPU shaders.
// So instead we add up the total weights and scale the result with that,
// so that we still end up with 0-1.
highp float totalWeigths = weights.x + weights.y * 2.0 + weights.z * 2.0 + weights.w * 2.0;
occlusion += shadowContrib(diff + perpendicular);
occlusion += shadowContrib(diff - perpendicular);
occlusion += shadowContrib(diff + perpendicular * 2.0);
occlusion += shadowContrib(diff - perpendicular * 2.0);
occlusion += shadowContrib(diff + perpendicular * 3.0);
occlusion += shadowContrib(diff - perpendicular * 3.0);
highp float occlusion = 0.0;
return occlusion / 7.0;
// Calculate actual occlusion with new weights.
occlusion += ChebyshevUpperBound(sample1, ourDist) * weights.x;
occlusion += ChebyshevUpperBound(sample2, ourDist) * weights.y;
occlusion += ChebyshevUpperBound(sample3, ourDist) * weights.y;
occlusion += ChebyshevUpperBound(sample4, ourDist) * weights.z;
occlusion += ChebyshevUpperBound(sample5, ourDist) * weights.z;
occlusion += ChebyshevUpperBound(sample6, ourDist) * weights.w;
occlusion += ChebyshevUpperBound(sample7, ourDist) * weights.w;
return occlusion / totalWeigths;
}