Soft-shadows XAVA post-render shader

post_frag_soft.glsl

precision mediump float;

varying vec2 v_texCoord;

uniform sampler2D s_texture;

const float pi = 3.14159265f;

const float check_steph = 0.00125;
const float check_stepv = 0.005;

void main() {
	vec4 sourcecol = texture2D(s_texture, v_texCoord);

	//vec2 offset = vec2(-0.002, 0.01);

	if(sourcecol.rgb == vec3(0.0, 0.0, 0.0)) {
		float intensity = 0.0;
		for(int i=-5; i<2; i++) {
			for(int j=-2; j<5; j++) {
				vec2 check_pos = v_texCoord.xy+vec2(float(i)*check_steph, float(j)*check_stepv);
				vec4 check_col = texture2D(s_texture, check_pos);
				if(check_col.rgb != vec3(0.0, 0.0, 0.0)) {
					intensity += 0.015;
				}
			}
		}
		gl_FragColor = vec4(0.0, 0.0, 0.0, intensity);
	} else gl_FragColor = sourcecol;
}