#version 450 core
#include "common.glsl"
// Depth-aware upsample of the AO buffer; output is multiplied into the HDR
// target by the blend unit (DST_COLOR, ZERO).

in vec2 vUV;
layout(binding = 0) uniform sampler2D uAo;
layout(binding = 1) uniform sampler2D uDepth;
uniform vec2 uAoTexel;
layout(location = 0) out vec4 fragColor;

void main() {
    float raw = texture(uDepth, vUV).r;
    if (raw >= 1.0) {
        fragColor = vec4(1.0);
        return;
    }
    float d0 = linearDepth(raw);
    float sum = 0.0, wsum = 0.0;
    for (int y = -1; y <= 1; ++y)
        for (int x = -1; x <= 1; ++x) {
            vec2 uv = vUV + vec2(x, y) * uAoTexel;
            float d = linearDepth(texture(uDepth, uv).r);
            float w = exp(-abs(d - d0) / (0.03 * d0 + 0.05));
            sum += texture(uAo, uv).r * w;
            wsum += w;
        }
    fragColor = vec4(vec3(sum / max(wsum, 1e-4)), 1.0);
}