quakeforge/libs/video/renderer/vulkan/shader/oit_blend.finc
Bill Currie 966ef949c5 [vulkan] Move oit blending into compose subpass
I had debated putting the blending in the compose subpass or a separate
pass but went with the separate pass originally, but it turns out that
removing the separate pass gains 1-3% (5-15/545 fps in a timedemo of
demo1).
2022-12-01 23:03:55 +09:00

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#include "oit.h"
vec4
BlendFrags (vec4 color)
{
#define MAX_FRAGMENTS 64
FragData frags[MAX_FRAGMENTS];
int numFrags = 0;
ivec2 coord = ivec2(gl_FragCoord.xy);
int index = imageLoad (heads, coord).r;
//FIXME use a heap and prioritize closer fragments
while (index != -1 && numFrags < MAX_FRAGMENTS) {
frags[numFrags] = fragments[index];
numFrags++;
index = fragments[index].next;
}
//insertion sort
for (int i = 1; i < numFrags; i++) {
FragData toInsert = frags[i];
int j = i;
while (j > 0 && toInsert.depth > frags[j - 1].depth) {
frags[j] = frags[j - 1];
j--;
}
frags[j] = toInsert;
}
for (int i = 0; i < numFrags; i++) {
color = mix (color, frags[i].color,
clamp (frags[i].color.a, 0.0f, 1.0f));
}
return color;
}