#extension GL_EXT_buffer_reference : require
#extension GL_EXT_nonuniform_qualifier : require
#extension GL_EXT_descriptor_heap : require

layout(local_size_x = 8, local_size_y = 8, local_size_z = 1) in;

layout(descriptor_heap, rgba32f) uniform image2D images[];

struct camera {
    vec4 position;

    vec4 forward;
    vec4 up;
    vec4 right;

    vec4 horizontal;
    vec4 vertical;
    vec4 first_pixel;

    float lens_radius;
    float fov;
    float focus_distance;
    float aspect_ratio;
};

layout(push_constant) uniform registers {
    int downscale_factor;
    uint output_image_index;
    uint accumulation_image_index;
} regs;

void main() {
    ivec2 coords = ivec2(gl_GlobalInvocationID.xy) * regs.downscale_factor;

    vec3 color = imageLoad(images[nonuniformEXT(regs.accumulation_image_index)], coords).rgb;
    vec3 out_color = sqrt(color);

    for (uint i = 0; i < regs.downscale_factor; i++) {
        for (uint j = 0; j < regs.downscale_factor; j++) {
            imageStore(images[nonuniformEXT(regs.output_image_index)], coords + ivec2(i, j), vec4(out_color, 1.0));
        }
    }
}