Gaussian Bloom

gaussianBloom.frag

uniform sampler2D renderedTexture;
uniform bool bloom;
uniform float bloomIntensity;
uniform float windowWidth;
uniform float windowHeight;

varying vec4 texCoord;


void main()
{
	vec4 sum = vec4(0);  

	if( bloom ) {
		vec4 source = texture2D(renderedTexture, vec2(texCoord.x, texCoord.y));
		
		float xBlurSize = 1.0 / windowWidth;

		sum += texture2D(renderedTexture, vec2(texCoord.x - 4.0*xBlurSize, texCoord.y)) * 0.05;
		sum += texture2D(renderedTexture, vec2(texCoord.x - 3.0*xBlurSize, texCoord.y)) * 0.09;
		sum += texture2D(renderedTexture, vec2(texCoord.x - 2.0*xBlurSize, texCoord.y)) * 0.12;
		sum += texture2D(renderedTexture, vec2(texCoord.x - xBlurSize, texCoord.y)) * 0.15;
		sum += source * 0.16;
		sum += texture2D(renderedTexture, vec2(texCoord.x + xBlurSize, texCoord.y)) * 0.15;
		sum += texture2D(renderedTexture, vec2(texCoord.x + 2.0*xBlurSize, texCoord.y)) * 0.12;
		sum += texture2D(renderedTexture, vec2(texCoord.x + 3.0*xBlurSize, texCoord.y)) * 0.09;
		sum += texture2D(renderedTexture, vec2(texCoord.x + 4.0*xBlurSize, texCoord.y)) * 0.05;

		// blur in y (vertical)
		// take nine samples, with the distance blurSize between them
		float yBlurSize = 1.0 / windowHeight;

		sum += texture2D(renderedTexture, vec2(texCoord.x, texCoord.y - 4.0*yBlurSize)) * 0.05;
		sum += texture2D(renderedTexture, vec2(texCoord.x, texCoord.y - 3.0*yBlurSize)) * 0.09;
		sum += texture2D(renderedTexture, vec2(texCoord.x, texCoord.y - 2.0*yBlurSize)) * 0.12;
		sum += texture2D(renderedTexture, vec2(texCoord.x, texCoord.y - yBlurSize)) * 0.15;
		sum += source * 0.16;
		sum += texture2D(renderedTexture, vec2(texCoord.x, texCoord.y + yBlurSize)) * 0.15;
		sum += texture2D(renderedTexture, vec2(texCoord.x, texCoord.y + 2.0*yBlurSize)) * 0.12;
		sum += texture2D(renderedTexture, vec2(texCoord.x, texCoord.y + 3.0*yBlurSize)) * 0.09;
		sum += texture2D(renderedTexture, vec2(texCoord.x, texCoord.y + 4.0*yBlurSize)) * 0.05;
	}

	gl_FragColor = sum * bloomIntensity + texture2D(renderedTexture, texCoord);
}