shader language=GLSL
	fragment~ filter=linear
		uniform sampler2D rubyTexture;
		uniform vec2 rubyInputSize;
		uniform vec2 rubyTextureSize;
		
		#define distortion 0.2
		
		vec2 barrelDistortion(vec2 coord) {
			vec2 cc = coord - 0.5;
			float dist = dot(cc, cc);
			return coord + cc * (dist + distortion * dist * dist) * distortion;
		}
		
		void main(void) {
			vec2 coord = barrelDistortion (gl_TexCoord[0] * rubyTextureSize / rubyInputSize) * rubyInputSize / rubyTextureSize;
			
			gl_FragColor = texture2D(rubyTexture, coord);
		}