vec2 Reprojection(vec3 pos) {
    pos = pos * 2.0 - 1.0;

    vec4 viewPosPrev = gbufferProjectionInverse * vec4(pos, 1.0);
    viewPosPrev /= viewPosPrev.w;
    viewPosPrev = gbufferModelViewInverse * viewPosPrev;

    vec3 cameraOffset = cameraPosition - previousCameraPosition;
    cameraOffset *= float(pos.z > 0.56);

    vec4 previousPosition = viewPosPrev + vec4(cameraOffset, 0.0);
    previousPosition = gbufferPreviousModelView * previousPosition;
    previousPosition = gbufferPreviousProjection * previousPosition;
    return previousPosition.xy / previousPosition.w * 0.5 + 0.5;
}

vec3 ApplyMultiColoredBlocklight(vec3 blocklightCol, vec3 screenPos) {
    if (screenPos.z > 0.56) {
        screenPos.xy = Reprojection(screenPos);
    }
    vec3 coloredLight = texture2D(colortex9, screenPos.xy).rgb;
    vec3 coloredLightNormalized = normalize(coloredLight + 0.00001);

    // do luminance correction for a seamless transition from the default blocklight color
    coloredLightNormalized *= GetLuminance(blocklightCol) / GetLuminance(coloredLightNormalized);

    float coloredLightMix = min1((coloredLight.r + coloredLight.g + coloredLight.b) * 2048);
    return mix(blocklightCol, coloredLightNormalized, coloredLightMix * MCBL_INFLUENCE);
}