#version 450

layout(binding = 0) uniform UniformBufferObject {
    mat4 model;
    mat4 geom_rot;
    mat4 view;
    mat4 proj;
    vec3 camera_pos;
    bool[16] use_geom_shader;
} ubo;

layout(binding = 3) readonly buffer CompoundBuffer {
   uint compounds[];
};

layout(binding = 4) readonly buffer ColorBuffer {
   uint grid_in[];
};

layout(binding = 9) readonly buffer TransparentBuffer {
   bool transparent_grid[];
};

layout(binding = 7) readonly buffer SizeBuffer2D {
   uint grid_size_in[];
};

layout(binding = 8) buffer SizeBuffer3D {
   uint grid_out[];
};

layout (local_size_x = 16, local_size_y = 1, local_size_z = 1) in;

void main() {
    uint index = gl_GlobalInvocationID.x * 2 + 1;
    uint output_offset = 0;
    uint compound_start = 1;
    // iterate over the compounds and find the work index inside of it
    while (index > compounds[compound_start] * compounds[compound_start]) {
        output_offset += compounds[compound_start] * compounds[compound_start] * compounds[compound_start];
        index -= compounds[compound_start] * compounds[compound_start];
        compound_start = compounds[compound_start + 2];
    }
    // grid pos in the task
    uint compound_grid_size = compounds[compound_start];
    float compound_scale = uintBitsToFloat(compounds[compound_start + 1]);
    vec3 mid_offset = vec3(compound_scale * 0.5, compound_scale * 0.5, compound_scale * 0.5);
    uint x = index % compound_grid_size;
    uint y = (index - x) / compound_grid_size;
    // iterate upwards along the z axis
    uint sum = 0;
    for (uint z=0; z < compound_grid_size; z++) {
        sum += grid_size_in[output_offset + x * compound_grid_size * compound_grid_size + y * compound_grid_size + z];
        grid_out[output_offset + x * compound_grid_size * compound_grid_size + y * compound_grid_size + z] = sum;
    }
}