#define TAU 6.28318530718

varying vec2 v_vTexcoord;
varying vec4 v_vColour;

uniform vec2  dimension;
uniform float radius;
uniform float threshold;

void main() {
	vec2 tx = 1. / dimension;
	vec4 cc = vec4(0.);
	float av = 0., dv = 0.;
	
	float stp = TAU / 64.;
	
	for(float i = 0.; i < radius; i++)
	for(float j = 0.; j < TAU; j += stp) {
		vec2 sx = v_vTexcoord + vec2(cos(j), sin(j)) * tx * i;
		
		vec4 c = texture2D( gm_BaseTexture, sx );
		
		cc += c;
		dv += 1.;
		av += c.a;
	}
	
	cc /= dv;
	
    gl_FragColor = step(threshold, cc);
}