/**
 * @author alteredq / http://alteredqualia.com/
 * @author davidedc / http://www.sketchpatch.net/
 *
 * NVIDIA FXAA by Timothy Lottes
 * http://timothylottes.blogspot.com/2011/06/fxaa3-source-released.html
 * - WebGL port by @supereggbert
 * http://www.glge.org/demos/fxaa/
 */

THREE.FXAAShader = {

	uniforms: {

		"tDiffuse":   { value: null },
		"resolution": { value: new THREE.Vector2( 1 / 1024, 1 / 512 ) }

	},

	vertexShader: [

		"void main() {",

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

		"}"

	].join( "\n" ),

	fragmentShader: [

		"uniform sampler2D tDiffuse;",
		"uniform vec2 resolution;",

		"#define FXAA_REDUCE_MIN   (1.0/128.0)",
		"#define FXAA_REDUCE_MUL   (1.0/8.0)",
		"#define FXAA_SPAN_MAX     8.0",

		"void main() {",

			"vec3 rgbNW = texture2D( tDiffuse, ( gl_FragCoord.xy + vec2( -1.0, -1.0 ) ) * resolution ).xyz;",
			"vec3 rgbNE = texture2D( tDiffuse, ( gl_FragCoord.xy + vec2( 1.0, -1.0 ) ) * resolution ).xyz;",
			"vec3 rgbSW = texture2D( tDiffuse, ( gl_FragCoord.xy + vec2( -1.0, 1.0 ) ) * resolution ).xyz;",
			"vec3 rgbSE = texture2D( tDiffuse, ( gl_FragCoord.xy + vec2( 1.0, 1.0 ) ) * resolution ).xyz;",
			"vec4 rgbaM  = texture2D( tDiffuse,  gl_FragCoord.xy  * resolution );",
			"vec3 rgbM  = rgbaM.xyz;",
			"vec3 luma = vec3( 0.299, 0.587, 0.114 );",

			"float lumaNW = dot( rgbNW, luma );",
			"float lumaNE = dot( rgbNE, luma );",
			"float lumaSW = dot( rgbSW, luma );",
			"float lumaSE = dot( rgbSE, luma );",
			"float lumaM  = dot( rgbM,  luma );",
			"float lumaMin = min( lumaM, min( min( lumaNW, lumaNE ), min( lumaSW, lumaSE ) ) );",
			"float lumaMax = max( lumaM, max( max( lumaNW, lumaNE) , max( lumaSW, lumaSE ) ) );",

			"vec2 dir;",
			"dir.x = -((lumaNW + lumaNE) - (lumaSW + lumaSE));",
			"dir.y =  ((lumaNW + lumaSW) - (lumaNE + lumaSE));",

			"float dirReduce = max( ( lumaNW + lumaNE + lumaSW + lumaSE ) * ( 0.25 * FXAA_REDUCE_MUL ), FXAA_REDUCE_MIN );",

			"float rcpDirMin = 1.0 / ( min( abs( dir.x ), abs( dir.y ) ) + dirReduce );",
			"dir = min( vec2( FXAA_SPAN_MAX,  FXAA_SPAN_MAX),",
				  "max( vec2(-FXAA_SPAN_MAX, -FXAA_SPAN_MAX),",
						"dir * rcpDirMin)) * resolution;",
			"vec4 rgbA = (1.0/2.0) * (",
        	"texture2D(tDiffuse,  gl_FragCoord.xy  * resolution + dir * (1.0/3.0 - 0.5)) +",
			"texture2D(tDiffuse,  gl_FragCoord.xy  * resolution + dir * (2.0/3.0 - 0.5)));",
    		"vec4 rgbB = rgbA * (1.0/2.0) + (1.0/4.0) * (",
			"texture2D(tDiffuse,  gl_FragCoord.xy  * resolution + dir * (0.0/3.0 - 0.5)) +",
      		"texture2D(tDiffuse,  gl_FragCoord.xy  * resolution + dir * (3.0/3.0 - 0.5)));",
    		"float lumaB = dot(rgbB, vec4(luma, 0.0));",

			"if ( ( lumaB < lumaMin ) || ( lumaB > lumaMax ) ) {",

				"gl_FragColor = rgbA;",

			"} else {",
				"gl_FragColor = rgbB;",

			"}",

		"}"

	].join( "\n" )

};
