/**
 * @author alteredq / http://alteredqualia.com/
 *
 * Film grain & scanlines shader
 *
 * - ported from HLSL to WebGL / GLSL
 * http://www.truevision3d.com/forums/showcase/staticnoise_colorblackwhite_scanline_shaders-t18698.0.html
 *
 * Screen Space Static Postprocessor
 *
 * Produces an analogue noise overlay similar to a film grain / TV static
 *
 * Original implementation and noise algorithm
 * Pat 'Hawthorne' Shearon
 *
 * Optimized scanlines + noise version with intensity scaling
 * Georg 'Leviathan' Steinrohder
 *
 * This version is provided under a Creative Commons Attribution 3.0 License
 * http://creativecommons.org/licenses/by/3.0/
 */



var FilmShader = {

	uniforms: {

		"tDiffuse": { value: null },
		"time": { value: 0.0 },
		"nIntensity": { value: 0.5 },
		"sIntensity": { value: 0.05 },
		"sCount": { value: 4096 },
		"grayscale": { value: 1 }

	},

	vertexShader: [

		"varying vec2 vUv;",

		"void main() {",

		"	vUv = uv;",
		"	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",

		"}"

	].join( "\n" ),

	fragmentShader: [

		"#include <common>",

		// control parameter
		"uniform float time;",

		"uniform bool grayscale;",

		// noise effect intensity value (0 = no effect, 1 = full effect)
		"uniform float nIntensity;",

		// scanlines effect intensity value (0 = no effect, 1 = full effect)
		"uniform float sIntensity;",

		// scanlines effect count value (0 = no effect, 4096 = full effect)
		"uniform float sCount;",

		"uniform sampler2D tDiffuse;",

		"varying vec2 vUv;",

		"void main() {",

		// sample the source
		"	vec4 cTextureScreen = texture2D( tDiffuse, vUv );",

		// make some noise
		"	float dx = rand( vUv + time );",

		// add noise
		"	vec3 cResult = cTextureScreen.rgb + cTextureScreen.rgb * clamp( 0.1 + dx, 0.0, 1.0 );",

		// get us a sine and cosine
		"	vec2 sc = vec2( sin( vUv.y * sCount ), cos( vUv.y * sCount ) );",

		// add scanlines
		"	cResult += cTextureScreen.rgb * vec3( sc.x, sc.y, sc.x ) * sIntensity;",

		// interpolate between source and result by intensity
		"	cResult = cTextureScreen.rgb + clamp( nIntensity, 0.0,1.0 ) * ( cResult - cTextureScreen.rgb );",

		// convert to grayscale if desired
		"	if( grayscale ) {",

		"		cResult = vec3( cResult.r * 0.3 + cResult.g * 0.59 + cResult.b * 0.11 );",

		"	}",

		"	gl_FragColor =  vec4( cResult, cTextureScreen.a );",

		"}"

	].join( "\n" )

};

export { FilmShader };
