#version 450
#extension GL_GOOGLE_include_directive : require
layout(local_size_x = 8, local_size_y = 8) in;
#include "common.glsl"

// The frame for the replay recorder at half size (2 x 2 average) when the window is wider than 1600 px: the copy to the host is a quarter
// (main.cpp; a 2560 x 1360 frame is 14 MB, copied every simulation tick).
layout(std430, set = 0, binding = 58) buffer ClipHalf { uint clipHalf[]; };
layout(std430, set = 0, binding = 60) readonly buffer ClipRaw { uint clipraw[]; };   // the window picture without the HUD (render.comp)

void main() {
    const ivec2 q = ivec2(gl_GlobalInvocationID.xy);
    const int hw = pc.ow / 2, hh = pc.oh / 2;
    if (q.x >= hw || q.y >= hh) return;
    const int i = 2 * q.y * pc.ow + 2 * q.x;
    const uvec4 a = uvec4(clipraw[i], clipraw[i + 1], clipraw[i + pc.ow], clipraw[i + pc.ow + 1]);
    uint o = 0u;
    for (int c = 0; c < 32; c += 8) {
        const uvec4 v = (a >> uint(c)) & 0xFFu;
        o |= ((v.x + v.y + v.z + v.w + 2u) >> 2) << uint(c);
    }
    clipHalf[q.y * hw + q.x] = o;
}