#version 150

precision highp float;

uniform sampler2D texture0;
uniform sampler2DShadow shadowMap;
uniform vec2 pixelOffset;

in vec2 texCoord;
in vec4 shadowCoord;

float pcf(vec2 offset){
    return textureProj(shadowMap,
                       shadowCoord+0.005+vec4(offset.x*pixelOffset.x*shadowCoord.w,
                                              offset.y*pixelOffset.y*shadowCoord.w,
                                              0.0,
                                              0.0));
}

void main(){
    float shadow = 1.0;

    if(shadowCoord.w > 0.0){
        float x, y;

        for(y = -1.5; y <= 1.5; y += 1.0){
            for(x = -1.5; x <= 1.5; x += 1.0){
                shadow += pcf(vec2(x, y));
            }
        }

        shadow /= 16.0;
    }

    gl_FragColor = shadow*texture(texture0, texCoord);
}