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Screen space dithering for PCF with some noise added

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This commit is contained in:
Olivier Prat 2017-11-13 12:33:46 +01:00
parent cbd2877524
commit dd0eaafc0d
1 changed files with 22 additions and 7 deletions
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29
libraries/render-utils/src/Shadow.slh
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@ -57,17 +57,32 @@ vec2 PCFkernel[4] = vec2[4](
vec2(0.5, -1.5)
);
float evalShadowAttenuationPCF(vec4 position, vec4 shadowTexcoord) {
float evalShadowNoise(vec4 seed) {
float dot_product = dot(seed, vec4(12.9898,78.233,45.164,94.673));
return fract(sin(dot_product) * 43758.5453);
}
float evalShadowAttenuationPCF(vec4 shadowTexcoord) {
float shadowScale = getShadowScale();
// Pattern dithering in screen space
// Offset for efficient PCF, see http://http.developer.nvidia.com/GPUGems/gpugems_ch11.html
vec2 offset = step(fract(position.xy), vec2(0.5, 0.5));
ivec2 coords = ivec2(gl_FragCoord.xy);
#if 1
// Add some noise to break dithering
int index = int(4.0*evalShadowNoise(gl_FragCoord.xyyx))%4;
coords.x += index & 1;
coords.y += (index & 2) >> 1;
#endif
ivec2 offset = coords & ivec2(1,1);
offset.y = (offset.x+offset.y) & 1;
vec2 offsetF = vec2(offset);
float shadowAttenuation = (0.25 * (
fetchShadow(shadowTexcoord.xyz + shadowScale * vec3(offset + PCFkernel[0], 0.0)) +
fetchShadow(shadowTexcoord.xyz + shadowScale * vec3(offset + PCFkernel[1], 0.0)) +
fetchShadow(shadowTexcoord.xyz + shadowScale * vec3(offset + PCFkernel[2], 0.0)) +
fetchShadow(shadowTexcoord.xyz + shadowScale * vec3(offset + PCFkernel[3], 0.0))
fetchShadow(shadowTexcoord.xyz + shadowScale * vec3(offsetF + PCFkernel[0], 0.0)) +
fetchShadow(shadowTexcoord.xyz + shadowScale * vec3(offsetF + PCFkernel[1], 0.0)) +
fetchShadow(shadowTexcoord.xyz + shadowScale * vec3(offsetF + PCFkernel[2], 0.0)) +
fetchShadow(shadowTexcoord.xyz + shadowScale * vec3(offsetF + PCFkernel[3], 0.0))
));
return shadowAttenuation;
@ -82,7 +97,7 @@ float evalShadowAttenuation(vec4 position) {
return 1.0;
}
return evalShadowAttenuationPCF(position, shadowTexcoord);
return evalShadowAttenuationPCF(shadowTexcoord);
}
<@endif@>