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/* Based on Separable SSS. by Jorge Jimenez and Diego Gutierrez */
#define MAX_SSS_SAMPLES 65
layout(std140) uniform sssProfile
{
vec4 kernel[MAX_SSS_SAMPLES];
vec4 radii_max_radius;
int sss_samples;
};
uniform sampler2D depthBuffer;
uniform sampler2D sssIrradiance;
uniform sampler2D sssRadius;
uniform sampler2D sssAlbedo;
#ifndef UTIL_TEX
# define UTIL_TEX
uniform sampler2DArray utilTex;
# define texelfetch_noise_tex(coord) texelFetch(utilTex, ivec3(ivec2(coord) % LUT_SIZE, 2.0), 0)
#endif /* UTIL_TEX */
layout(location = 0) out vec4 sssRadiance;
float get_view_z_from_depth(float depth)
{
if (ProjectionMatrix[3][3] == 0.0) {
float d = 2.0 * depth - 1.0;
return -ProjectionMatrix[3][2] / (d + ProjectionMatrix[2][2]);
}
else {
return viewVecs[0].z + depth * viewVecs[1].z;
}
}
#define LUT_SIZE 64
#define M_PI_2 1.5707963267948966 /* pi/2 */
#define M_2PI 6.2831853071795865 /* 2*pi */
void main(void)
{
vec2 pixel_size = 1.0 / vec2(textureSize(depthBuffer, 0).xy); /* TODO precompute */
vec2 uvs = gl_FragCoord.xy * pixel_size;
vec3 sss_irradiance = texture(sssIrradiance, uvs).rgb;
float sss_radius = texture(sssRadius, uvs).r;
float depth_view = get_view_z_from_depth(texture(depthBuffer, uvs).r);
float rand = texelfetch_noise_tex(gl_FragCoord.xy).r;
#ifdef FIRST_PASS
float angle = M_2PI * rand + M_PI_2;
vec2 dir = vec2(1.0, 0.0);
#else /* SECOND_PASS */
float angle = M_2PI * rand;
vec2 dir = vec2(0.0, 1.0);
#endif
vec2 dir_rand = vec2(cos(angle), sin(angle));
/* Compute kernel bounds in 2D. */
float homcoord = ProjectionMatrix[2][3] * depth_view + ProjectionMatrix[3][3];
vec2 scale = vec2(ProjectionMatrix[0][0], ProjectionMatrix[1][1]) * sss_radius / homcoord;
vec2 finalStep = scale * radii_max_radius.w;
finalStep *= 0.5; /* samples range -1..1 */
/* Center sample */
vec3 accum = sss_irradiance * kernel[0].rgb;
for (int i = 1; i < sss_samples && i < MAX_SSS_SAMPLES; i++) {
vec2 sample_uv = uvs + kernel[i].a * finalStep *
((abs(kernel[i].a) > sssJitterThreshold) ? dir : dir_rand);
vec3 color = texture(sssIrradiance, sample_uv).rgb;
float sample_depth = texture(depthBuffer, sample_uv).r;
sample_depth = get_view_z_from_depth(sample_depth);
/* Depth correction factor. */
float depth_delta = depth_view - sample_depth;
float s = clamp(1.0 - exp(-(depth_delta * depth_delta) / (2.0 * sss_radius)), 0.0, 1.0);
/* Out of view samples. */
if (any(lessThan(sample_uv, vec2(0.0))) || any(greaterThan(sample_uv, vec2(1.0)))) {
s = 1.0;
}
/* Mix with first sample in failure case and apply kernel color. */
accum += kernel[i].rgb * mix(color, sss_irradiance, s);
}
#if defined(FIRST_PASS)
sssRadiance = vec4(accum, 1.0);
#else /* SECOND_PASS */
sssRadiance = vec4(accum * texture(sssAlbedo, uvs).rgb, 1.0);
#endif
}
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