#version 450
// Copyright (c) 2025 Hans-Kristian Arntzen
// SPDX-License-Identifier: MIT
#extension GL_EXT_samplerless_texture_functions : require

layout(set = 0, binding = 0) uniform texture2D uTex;
layout(set = 0, binding = 1) writeonly uniform image2D uImage;

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

float power_to_db(float p)
{
    return max(10.0 * log2(p) / log2(10.0), -100.0);
}

void main()
{
    float input_power = 0.0;
    const int Stride = 8;
    for (int y = 0; y < Stride; y++)
    {
        for (int x = 0; x < Stride; x++)
        {
            if (any(notEqual(ivec4(gl_GlobalInvocationID.xy, x, y), ivec4(0))))
            {
                vec2 c = texelFetch(uTex, ivec2(gl_GlobalInvocationID.xy) * Stride + ivec2(x, y), 0).xy;
                input_power += dot(c, c);
            }
        }
    }

    imageStore(uImage, ivec2(gl_GlobalInvocationID.xy), vec4(power_to_db(input_power)));
}