#version 150

in vec2 vTexCoord;

uniform sampler2D flame_fbo;
uniform sampler2D light_fbo;
uniform int windowSizeX;
uniform int windowSizeY;

out vec4 oColor;

const float lookup_offset = 4.0;

void main() {
    vec4 color = texture(flame_fbo, vTexCoord).rgba;
    if (color == vec4(0.0, 0.0, 0.0, 1.0)) {
        oColor = texture(light_fbo, vTexCoord).rgba;
    }
    else {
        vec4 sum = vec4(0.0);
        for(float i = -lookup_offset; i<=lookup_offset; i+=1.0) {
            for(float j = -lookup_offset; j<=lookup_offset; j+=1.0) {
                vec4 flame_pixel = texture(flame_fbo, vec2(vTexCoord.x + i * 1.0/(windowSizeX/2.0), vTexCoord.y + j * 1.0/(windowSizeY/2.0)))/pow(lookup_offset*2+1, 2.0);
                vec4 light_pixel = texture(light_fbo, vec2(vTexCoord.x + i * 1.0/(windowSizeX/2.0), vTexCoord.y + j * 1.0/(windowSizeY/2.0)))/pow(lookup_offset*2+1, 2.0);
                if (flame_pixel == vec4(0.0, 0.0, 0.0, 1.0)) {
                    sum += light_pixel;
                }
                else {
                    sum += mix(flame_pixel, light_pixel, 0.7);
                }
            }
        }
        oColor = sum;
    }
}