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#pragma BLENDER_REQUIRE(common_view_lib.glsl)
#pragma BLENDER_REQUIRE(workbench_common_lib.glsl)
/* From The Alchemy screen-space ambient obscurance algorithm
* http://graphics.cs.williams.edu/papers/AlchemyHPG11/VV11AlchemyAO.pdf */
#ifdef USE_CAVITY
void cavity_compute(vec2 screenco,
sampler2D depthBuffer,
sampler2D normalBuffer,
out float cavities,
out float edges)
{
cavities = edges = 0.0;
float depth = texture(depthBuffer, screenco).x;
/* Early out if background and in front. */
if (depth == 1.0 || depth == 0.0) {
return;
}
vec3 position = get_view_space_from_depth(screenco, depth);
vec3 normal = workbench_normal_decode(texture(normalBuffer, screenco));
vec2 jitter_co = (screenco * world_data.viewport_size.xy) * world_data.cavity_jitter_scale;
vec3 noise = texture(cavityJitter, jitter_co).rgb;
/* find the offset in screen space by multiplying a point
* in camera space at the depth of the point by the projection matrix. */
vec2 offset;
float homcoord = ProjectionMatrix[2][3] * position.z + ProjectionMatrix[3][3];
offset.x = ProjectionMatrix[0][0] * world_data.cavity_distance / homcoord;
offset.y = ProjectionMatrix[1][1] * world_data.cavity_distance / homcoord;
/* convert from -1.0...1.0 range to 0.0..1.0 for easy use with texture coordinates */
offset *= 0.5;
/* NOTE: Putting noise usage here to put some ALU after texture fetch. */
vec2 rotX = noise.rg;
vec2 rotY = vec2(-rotX.y, rotX.x);
int sample_start = world_data.cavity_sample_start;
int sample_end = world_data.cavity_sample_end;
for (int i = sample_start; i < sample_end && i < 512; i++) {
/* sample_coord.xy is sample direction (normalized).
* sample_coord.z is sample distance from disk center. */
vec3 sample_coord = samples_coords[i].xyz;
/* Rotate with random direction to get jittered result. */
vec2 dir_jittered = vec2(dot(sample_coord.xy, rotX), dot(sample_coord.xy, rotY));
dir_jittered.xy *= sample_coord.z + noise.b;
vec2 uvcoords = screenco + dir_jittered * offset;
/* Out of screen case. */
if (any(greaterThan(abs(uvcoords - 0.5), vec2(0.5)))) {
continue;
}
/* Sample depth. */
float s_depth = texture(depthBuffer, uvcoords).r;
/* Handle Background case */
bool is_background = (s_depth == 1.0);
/* This trick provide good edge effect even if no neighbor is found. */
s_depth = (is_background) ? depth : s_depth;
vec3 s_pos = get_view_space_from_depth(uvcoords, s_depth);
if (is_background) {
s_pos.z -= world_data.cavity_distance;
}
vec3 dir = s_pos - position;
float len = length(dir);
float f_cavities = dot(dir, normal);
float f_edge = -f_cavities;
float f_bias = 0.05 * len + 0.0001;
float attenuation = 1.0 / (len * (1.0 + len * len * world_data.cavity_attenuation));
/* use minor bias here to avoid self shadowing */
if (f_cavities > -f_bias) {
cavities += f_cavities * attenuation;
}
if (f_edge > f_bias) {
edges += f_edge * attenuation;
}
}
cavities *= world_data.cavity_sample_count_inv;
edges *= world_data.cavity_sample_count_inv;
/* don't let cavity wash out the surface appearance */
cavities = clamp(cavities * world_data.cavity_valley_factor, 0.0, 1.0);
edges = edges * world_data.cavity_ridge_factor;
}
#endif /* USE_CAVITY */
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