precision mediump float;

uniform sampler2D uOcclusion;
uniform vec4 uBackground;

varying vec2 fUV;

void main() {
    float occ = 1.0 - texture2D(uOcclusion, fUV).x;
    gl_FragColor = vec4(uBackground.x * occ, uBackground.y * occ, uBackground.z * occ, occ);
}