/**
 * RGB Shift Shader
 * Shifts red and blue channels from center in opposite directions
 * Ported from http://kriss.cx/tom/2009/05/rgb-shift/
 * by Tom Butterworth / http://kriss.cx/tom/
 *
 * amount: shift distance (1 is width of input)
 * angle: shift angle in radians
 */

var DigitalGlitch = {

	uniforms: {

		'tDiffuse': { value: null }, //diffuse texture
		'tDisp': { value: null }, //displacement texture for digital glitch squares
		'byp': { value: 0 }, //apply the glitch ?
		'amount': { value: 0.08 },
		'angle': { value: 0.02 },
		'seed': { value: 0.02 },
		'seed_x': { value: 0.02 }, //-1,1
		'seed_y': { value: 0.02 }, //-1,1
		'distortion_x': { value: 0.5 },
		'distortion_y': { value: 0.6 },
		'col_s': { value: 0.05 }
	},

	vertexShader: [

		'varying vec2 vUv;',
		'void main() {',
		'	vUv = uv;',
		'	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );',
		'}'
	].join( '\n' ),

	fragmentShader: [
		'uniform int byp;', //should we apply the glitch ?

		'uniform sampler2D tDiffuse;',
		'uniform sampler2D tDisp;',

		'uniform float amount;',
		'uniform float angle;',
		'uniform float seed;',
		'uniform float seed_x;',
		'uniform float seed_y;',
		'uniform float distortion_x;',
		'uniform float distortion_y;',
		'uniform float col_s;',

		'varying vec2 vUv;',


		'float rand(vec2 co){',
		'	return fract(sin(dot(co.xy ,vec2(12.9898,78.233))) * 43758.5453);',
		'}',

		'void main() {',
		'	if(byp<1) {',
		'		vec2 p = vUv;',
		'		float xs = floor(gl_FragCoord.x / 0.5);',
		'		float ys = floor(gl_FragCoord.y / 0.5);',
		//based on staffantans glitch shader for unity https://github.com/staffantan/unityglitch
		'		vec4 normal = texture2D (tDisp, p*seed*seed);',
		'		if(p.y<distortion_x+col_s && p.y>distortion_x-col_s*seed) {',
		'			if(seed_x>0.){',
		'				p.y = 1. - (p.y + distortion_y);',
		'			}',
		'			else {',
		'				p.y = distortion_y;',
		'			}',
		'		}',
		'		if(p.x<distortion_y+col_s && p.x>distortion_y-col_s*seed) {',
		'			if(seed_y>0.){',
		'				p.x=distortion_x;',
		'			}',
		'			else {',
		'				p.x = 1. - (p.x + distortion_x);',
		'			}',
		'		}',
		'		p.x+=normal.x*seed_x*(seed/5.);',
		'		p.y+=normal.y*seed_y*(seed/5.);',
		//base from RGB shift shader
		'		vec2 offset = amount * vec2( cos(angle), sin(angle));',
		'		vec4 cr = texture2D(tDiffuse, p + offset);',
		'		vec4 cga = texture2D(tDiffuse, p);',
		'		vec4 cb = texture2D(tDiffuse, p - offset);',
		'		gl_FragColor = vec4(cr.r, cga.g, cb.b, cga.a);',
		//add noise
		'		vec4 snow = 200.*amount*vec4(rand(vec2(xs * seed,ys * seed*50.))*0.2);',
		'		gl_FragColor = gl_FragColor+ snow;',
		'	}',
		'	else {',
		'		gl_FragColor=texture2D (tDiffuse, vUv);',
		'	}',
		'}'

	].join( '\n' )

};

export { DigitalGlitch };