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uniform samplerCube probeDepth;
uniform int outputSize;
uniform float lodFactor;
uniform float storedTexelSize;
uniform float lodMax;
uniform float nearClip;
uniform float farClip;
uniform float visibilityRange;
uniform float visibilityBlur;
out vec4 FragColor;
vec3 octahedral_to_cubemap_proj(vec2 co)
{
co = co * 2.0 - 1.0;
vec2 abs_co = abs(co);
vec3 v = vec3(co, 1.0 - (abs_co.x + abs_co.y));
if ( abs_co.x + abs_co.y > 1.0 ) {
v.xy = (abs(co.yx) - 1.0) * -sign(co.xy);
}
return v;
}
float linear_depth(float z)
{
return (nearClip * farClip) / (z * (nearClip - farClip) + farClip);
}
float get_world_distance(float depth, vec3 cos)
{
float is_background = step(1.0, depth);
depth = linear_depth(depth);
depth += 1e1 * is_background;
cos = normalize(abs(cos));
float cos_vec = max(cos.x, max(cos.y, cos.z));
return depth / cos_vec;
}
void main()
{
ivec2 texel = ivec2(gl_FragCoord.xy) % ivec2(outputSize);
vec3 cos;
cos.xy = (vec2(texel) + 0.5) * storedTexelSize;
/* add a 2 pixel border to ensure filtering is correct */
cos.xy *= 1.0 + storedTexelSize * 2.0;
cos.xy -= storedTexelSize;
float pattern = 1.0;
/* edge mirroring : only mirror if directly adjacent
* (not diagonally adjacent) */
vec2 m = abs(cos.xy - 0.5) + 0.5;
vec2 f = floor(m);
if (f.x - f.y != 0.0) {
cos.xy = 1.0 - cos.xy;
}
/* clamp to [0-1] */
cos.xy = fract(cos.xy);
/* get cubemap vector */
cos = normalize(octahedral_to_cubemap_proj(cos.xy));
vec3 T, B;
make_orthonormal_basis(cos, T, B); /* Generate tangent space */
vec2 accum = vec2(0.0);
for (float i = 0; i < sampleCount; i++) {
vec3 sample = sample_cone(i, M_PI_2 * visibilityBlur, cos, T, B);
float depth = texture(probeDepth, sample).r;
depth = get_world_distance(depth, sample);
accum += vec2(depth, depth * depth);
}
accum *= invSampleCount;
accum = abs(accum);
/* Encode to normalized RGBA 8 */
FragColor = visibility_encode(accum, visibilityRange);
}
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