text: /**
   * @author mpk / http://polko.me/
   *
   * WebGL port of Subpixel Morphological Antialiasing (SMAA) v2.8
   * Preset: SMAA 1x Medium (with color edge detection)
   * https://github.com/iryoku/smaa/releases/tag/v2.8
   */
  
  THREE.SMAAShader = [ {
  
  	defines: {
  
  		"SMAA_THRESHOLD": "0.1"
  
  	},
  
  	uniforms: {
  
  		"tDiffuse":		{ type: "t", value: null },
  		"resolution":	{ type: "v2", value: new THREE.Vector2( 1 / 1024, 1 / 512 ) }
  
  	},
  
  	vertexShader: [
  
  		"uniform vec2 resolution;",
  
  		"varying vec2 vUv;",
  		"varying vec4 vOffset[ 3 ];",
  
  		"void SMAAEdgeDetectionVS( vec2 texcoord ) {",
  			"vOffset[ 0 ] = texcoord.xyxy + resolution.xyxy * vec4( -1.0, 0.0, 0.0,  1.0 );", // WebGL port note: Changed sign in W component
  			"vOffset[ 1 ] = texcoord.xyxy + resolution.xyxy * vec4(  1.0, 0.0, 0.0, -1.0 );", // WebGL port note: Changed sign in W component
  			"vOffset[ 2 ] = texcoord.xyxy + resolution.xyxy * vec4( -2.0, 0.0, 0.0,  2.0 );", // WebGL port note: Changed sign in W component
  		"}",
  
  		"void main() {",
  
  			"vUv = uv;",
  
  			"SMAAEdgeDetectionVS( vUv );",
  
  			"gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",
  
  		"}"
  
  	].join("\n"),
  
  	fragmentShader: [
  
  		"uniform sampler2D tDiffuse;",
  
  		"varying vec2 vUv;",
  		"varying vec4 vOffset[ 3 ];",
  
  		"vec4 SMAAColorEdgeDetectionPS( vec2 texcoord, vec4 offset[3], sampler2D colorTex ) {",
  			"vec2 threshold = vec2( SMAA_THRESHOLD, SMAA_THRESHOLD );",
  
  			// Calculate color deltas:
  			"vec4 delta;",
  			"vec3 C = texture2D( colorTex, texcoord ).rgb;",
  
  			"vec3 Cleft = texture2D( colorTex, offset[0].xy ).rgb;",
  			"vec3 t = abs( C - Cleft );",
  			"delta.x = max( max( t.r, t.g ), t.b );",
  
  			"vec3 Ctop = texture2D( colorTex, offset[0].zw ).rgb;",
  			"t = abs( C - Ctop );",
  			"delta.y = max( max( t.r, t.g ), t.b );",
  
  			// We do the usual threshold:
  			"vec2 edges = step( threshold, delta.xy );",
  
  			// Then discard if there is no edge:
  			"if ( dot( edges, vec2( 1.0, 1.0 ) ) == 0.0 )",
  				"discard;",
  
  			// Calculate right and bottom deltas:
  			"vec3 Cright = texture2D( colorTex, offset[1].xy ).rgb;",
  			"t = abs( C - Cright );",
  			"delta.z = max( max( t.r, t.g ), t.b );",
  
  			"vec3 Cbottom  = texture2D( colorTex, offset[1].zw ).rgb;",
  			"t = abs( C - Cbottom );",
  			"delta.w = max( max( t.r, t.g ), t.b );",
  
  			// Calculate the maximum delta in the direct neighborhood:
  			"float maxDelta = max( max( max( delta.x, delta.y ), delta.z ), delta.w );",
  
  			// Calculate left-left and top-top deltas:
  			"vec3 Cleftleft  = texture2D( colorTex, offset[2].xy ).rgb;",
  			"t = abs( C - Cleftleft );",
  			"delta.z = max( max( t.r, t.g ), t.b );",
  
  			"vec3 Ctoptop = texture2D( colorTex, offset[2].zw ).rgb;",
  			"t = abs( C - Ctoptop );",
  			"delta.w = max( max( t.r, t.g ), t.b );",
  
  			// Calculate the final maximum delta:
  			"maxDelta = max( max( maxDelta, delta.z ), delta.w );",
  
  			// Local contrast adaptation in action:
  			"edges.xy *= step( 0.5 * maxDelta, delta.xy );",
  
  			"return vec4( edges, 0.0, 0.0 );",
  		"}",
  
  		"void main() {",
  
  			"gl_FragColor = SMAAColorEdgeDetectionPS( vUv, vOffset, tDiffuse );",
  
  		"}"
  
  	].join("\n")
  
  }, {
  
  	defines: {
  
  		"SMAA_MAX_SEARCH_STEPS":		"8",
  		"SMAA_AREATEX_MAX_DISTANCE":	"16",
  		"SMAA_AREATEX_PIXEL_SIZE":		"( 1.0 / vec2( 160.0, 560.0 ) )",
  		"SMAA_AREATEX_SUBTEX_SIZE":		"( 1.0 / 7.0 )"
  
  	},
  
  	uniforms: {
  
  		"tDiffuse":		{ type: "t", value: null },
  		"tArea":		{ type: "t", value: null },
  		"tSearch":		{ type: "t", value: null },
  		"resolution":	{ type: "v2", value: new THREE.Vector2( 1 / 1024, 1 / 512 ) }
  
  	},
  
  	vertexShader: [
  
  		"uniform vec2 resolution;",
  
  		"varying vec2 vUv;",
  		"varying vec4 vOffset[ 3 ];",
  		"varying vec2 vPixcoord;",
  
  		"void SMAABlendingWeightCalculationVS( vec2 texcoord ) {",
  			"vPixcoord = texcoord / resolution;",
  
  			// We will use these offsets for the searches later on (see @PSEUDO_GATHER4):
  			"vOffset[ 0 ] = texcoord.xyxy + resolution.xyxy * vec4( -0.25, 0.125, 1.25, 0.125 );", // WebGL port note: Changed sign in Y and W components
  			"vOffset[ 1 ] = texcoord.xyxy + resolution.xyxy * vec4( -0.125, 0.25, -0.125, -1.25 );", // WebGL port note: Changed sign in Y and W components
  
  			// And these for the searches, they indicate the ends of the loops:
  			"vOffset[ 2 ] = vec4( vOffset[ 0 ].xz, vOffset[ 1 ].yw ) + vec4( -2.0, 2.0, -2.0, 2.0 ) * resolution.xxyy * float( SMAA_MAX_SEARCH_STEPS );",
  
  		"}",
  
  		"void main() {",
  
  			"vUv = uv;",
  
  			"SMAABlendingWeightCalculationVS( vUv );",
  
  			"gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",
  
  		"}"
  
  	].join("\n"),
  
  	fragmentShader: [
  
  		"#define SMAASampleLevelZeroOffset( tex, coord, offset ) texture2D( tex, coord + float( offset ) * resolution, 0.0 )",
  
  		"uniform sampler2D tDiffuse;",
  		"uniform sampler2D tArea;",
  		"uniform sampler2D tSearch;",
  		"uniform vec2 resolution;",
  
  		"varying vec2 vUv;",
  		"varying vec4 vOffset[3];",
  		"varying vec2 vPixcoord;",
  
  		"vec2 round( vec2 x ) {",
  			"return sign( x ) * floor( abs( x ) + 0.5 );",
  		"}",
  
  		"float SMAASearchLength( sampler2D searchTex, vec2 e, float bias, float scale ) {",
  			// Not required if searchTex accesses are set to point:
  			// float2 SEARCH_TEX_PIXEL_SIZE = 1.0 / float2(66.0, 33.0);
  			// e = float2(bias, 0.0) + 0.5 * SEARCH_TEX_PIXEL_SIZE +
  			//     e * float2(scale, 1.0) * float2(64.0, 32.0) * SEARCH_TEX_PIXEL_SIZE;
  			"e.r = bias + e.r * scale;",
  			"return 255.0 * texture2D( searchTex, e, 0.0 ).r;",
  		"}",
  
  		"float SMAASearchXLeft( sampler2D edgesTex, sampler2D searchTex, vec2 texcoord, float end ) {",
  			/**
  			* @PSEUDO_GATHER4
  			* This texcoord has been offset by (-0.25, -0.125) in the vertex shader to
  			* sample between edge, thus fetching four edges in a row.
  			* Sampling with different offsets in each direction allows to disambiguate
  			* which edges are active from the four fetched ones.
  			*/
  			"vec2 e = vec2( 0.0, 1.0 );",
  
  			"for ( int i = 0; i < SMAA_MAX_SEARCH_STEPS; i ++ ) {", // WebGL port note: Changed while to for
  				"e = texture2D( edgesTex, texcoord, 0.0 ).rg;",
  				"texcoord -= vec2( 2.0, 0.0 ) * resolution;",
  				"if ( ! ( texcoord.x > end && e.g > 0.8281 && e.r == 0.0 ) ) break;",
  			"}",
  
  			// We correct the previous (-0.25, -0.125) offset we applied:
  			"texcoord.x += 0.25 * resolution.x;",
  
  			// The searches are bias by 1, so adjust the coords accordingly:
  			"texcoord.x += resolution.x;",
  
  			// Disambiguate the length added by the last step:
  			"texcoord.x += 2.0 * resolution.x;", // Undo last step
  			"texcoord.x -= resolution.x * SMAASearchLength(searchTex, e, 0.0, 0.5);",
  
  			"return texcoord.x;",
  		"}",
  
  		"float SMAASearchXRight( sampler2D edgesTex, sampler2D searchTex, vec2 texcoord, float end ) {",
  			"vec2 e = vec2( 0.0, 1.0 );",
  
  			"for ( int i = 0; i < SMAA_MAX_SEARCH_STEPS; i ++ ) {", // WebGL port note: Changed while to for
  				"e = texture2D( edgesTex, texcoord, 0.0 ).rg;",
  				"texcoord += vec2( 2.0, 0.0 ) * resolution;",
  				"if ( ! ( texcoord.x < end && e.g > 0.8281 && e.r == 0.0 ) ) break;",
  			"}",
  
  			"texcoord.x -= 0.25 * resolution.x;",
  			"texcoord.x -= resolution.x;",
  			"texcoord.x -= 2.0 * resolution.x;",
  			"texcoord.x += resolution.x * SMAASearchLength( searchTex, e, 0.5, 0.5 );",
  
  			"return texcoord.x;",
  		"}",
  
  		"float SMAASearchYUp( sampler2D edgesTex, sampler2D searchTex, vec2 texcoord, float end ) {",
  			"vec2 e = vec2( 1.0, 0.0 );",
  
  			"for ( int i = 0; i < SMAA_MAX_SEARCH_STEPS; i ++ ) {", // WebGL port note: Changed while to for
  				"e = texture2D( edgesTex, texcoord, 0.0 ).rg;",
  				"texcoord += vec2( 0.0, 2.0 ) * resolution;", // WebGL port note: Changed sign
  				"if ( ! ( texcoord.y > end && e.r > 0.8281 && e.g == 0.0 ) ) break;",
  			"}",
  
  			"texcoord.y -= 0.25 * resolution.y;", // WebGL port note: Changed sign
  			"texcoord.y -= resolution.y;", // WebGL port note: Changed sign
  			"texcoord.y -= 2.0 * resolution.y;", // WebGL port note: Changed sign
  			"texcoord.y += resolution.y * SMAASearchLength( searchTex, e.gr, 0.0, 0.5 );", // WebGL port note: Changed sign
  
  			"return texcoord.y;",
  		"}",
  
  		"float SMAASearchYDown( sampler2D edgesTex, sampler2D searchTex, vec2 texcoord, float end ) {",
  			"vec2 e = vec2( 1.0, 0.0 );",
  
  			"for ( int i = 0; i < SMAA_MAX_SEARCH_STEPS; i ++ ) {", // WebGL port note: Changed while to for
  				"e = texture2D( edgesTex, texcoord, 0.0 ).rg;",
  				"texcoord -= vec2( 0.0, 2.0 ) * resolution;", // WebGL port note: Changed sign
  				"if ( ! ( texcoord.y < end && e.r > 0.8281 && e.g == 0.0 ) ) break;",
  			"}",
  
  			"texcoord.y += 0.25 * resolution.y;", // WebGL port note: Changed sign
  			"texcoord.y += resolution.y;", // WebGL port note: Changed sign
  			"texcoord.y += 2.0 * resolution.y;", // WebGL port note: Changed sign
  			"texcoord.y -= resolution.y * SMAASearchLength( searchTex, e.gr, 0.5, 0.5 );", // WebGL port note: Changed sign
  
  			"return texcoord.y;",
  		"}",
  
  		"vec2 SMAAArea( sampler2D areaTex, vec2 dist, float e1, float e2, float offset ) {",
  			// Rounding prevents precision errors of bilinear filtering:
  			"vec2 texcoord = float( SMAA_AREATEX_MAX_DISTANCE ) * round( 4.0 * vec2( e1, e2 ) ) + dist;",
  
  			// We do a scale and bias for mapping to texel space:
  			"texcoord = SMAA_AREATEX_PIXEL_SIZE * texcoord + ( 0.5 * SMAA_AREATEX_PIXEL_SIZE );",
  
  			// Move to proper place, according to the subpixel offset:
  			"texcoord.y += SMAA_AREATEX_SUBTEX_SIZE * offset;",
  
  			"return texture2D( areaTex, texcoord, 0.0 ).rg;",
  		"}",
  
  		"vec4 SMAABlendingWeightCalculationPS( vec2 texcoord, vec2 pixcoord, vec4 offset[ 3 ], sampler2D edgesTex, sampler2D areaTex, sampler2D searchTex, ivec4 subsampleIndices ) {",
  			"vec4 weights = vec4( 0.0, 0.0, 0.0, 0.0 );",
  
  			"vec2 e = texture2D( edgesTex, texcoord ).rg;",
  
  			"if ( e.g > 0.0 ) {", // Edge at north
  				"vec2 d;",
  
  				// Find the distance to the left:
  				"vec2 coords;",
  				"coords.x = SMAASearchXLeft( edgesTex, searchTex, offset[ 0 ].xy, offset[ 2 ].x );",
  				"coords.y = offset[ 1 ].y;", // offset[1].y = texcoord.y - 0.25 * resolution.y (@CROSSING_OFFSET)
  				"d.x = coords.x;",
  
  				// Now fetch the left crossing edges, two at a time using bilinear
  				// filtering. Sampling at -0.25 (see @CROSSING_OFFSET) enables to
  				// discern what value each edge has:
  				"float e1 = texture2D( edgesTex, coords, 0.0 ).r;",
  
  				// Find the distance to the right:
  				"coords.x = SMAASearchXRight( edgesTex, searchTex, offset[ 0 ].zw, offset[ 2 ].y );",
  				"d.y = coords.x;",
  
  				// We want the distances to be in pixel units (doing this here allow to
  				// better interleave arithmetic and memory accesses):
  				"d = d / resolution.x - pixcoord.x;",
  
  				// SMAAArea below needs a sqrt, as the areas texture is compressed
  				// quadratically:
  				"vec2 sqrt_d = sqrt( abs( d ) );",
  
  				// Fetch the right crossing edges:
  				"coords.y -= 1.0 * resolution.y;", // WebGL port note: Added
  				"float e2 = SMAASampleLevelZeroOffset( edgesTex, coords, ivec2( 1, 0 ) ).r;",
  
  				// Ok, we know how this pattern looks like, now it is time for getting
  				// the actual area:
  				"weights.rg = SMAAArea( areaTex, sqrt_d, e1, e2, float( subsampleIndices.y ) );",
  			"}",
  
  			"if ( e.r > 0.0 ) {", // Edge at west
  				"vec2 d;",
  
  				// Find the distance to the top:
  				"vec2 coords;",
  
  				"coords.y = SMAASearchYUp( edgesTex, searchTex, offset[ 1 ].xy, offset[ 2 ].z );",
  				"coords.x = offset[ 0 ].x;", // offset[1].x = texcoord.x - 0.25 * resolution.x;
  				"d.x = coords.y;",
  
  				// Fetch the top crossing edges:
  				"float e1 = texture2D( edgesTex, coords, 0.0 ).g;",
  
  				// Find the distance to the bottom:
  				"coords.y = SMAASearchYDown( edgesTex, searchTex, offset[ 1 ].zw, offset[ 2 ].w );",
  				"d.y = coords.y;",
  
  				// We want the distances to be in pixel units:
  				"d = d / resolution.y - pixcoord.y;",
  
  				// SMAAArea below needs a sqrt, as the areas texture is compressed
  				// quadratically:
  				"vec2 sqrt_d = sqrt( abs( d ) );",
  
  				// Fetch the bottom crossing edges:
  				"coords.y -= 1.0 * resolution.y;", // WebGL port note: Added
  				"float e2 = SMAASampleLevelZeroOffset( edgesTex, coords, ivec2( 0, 1 ) ).g;",
  
  				// Get the area for this direction:
  				"weights.ba = SMAAArea( areaTex, sqrt_d, e1, e2, float( subsampleIndices.x ) );",
  			"}",
  
  			"return weights;",
  		"}",
  
  		"void main() {",
  
  			"gl_FragColor = SMAABlendingWeightCalculationPS( vUv, vPixcoord, vOffset, tDiffuse, tArea, tSearch, ivec4( 0.0 ) );",
  
  		"}"
  
  	].join("\n")
  
  }, {
  
  	uniforms: {
  
  		"tDiffuse":		{ type: "t", value: null },
  		"tColor":		{ type: "t", value: null },
  		"resolution":	{ type: "v2", value: new THREE.Vector2( 1 / 1024, 1 / 512 ) }
  
  	},
  
  	vertexShader: [
  
  		"uniform vec2 resolution;",
  
  		"varying vec2 vUv;",
  		"varying vec4 vOffset[ 2 ];",
  
  		"void SMAANeighborhoodBlendingVS( vec2 texcoord ) {",
  			"vOffset[ 0 ] = texcoord.xyxy + resolution.xyxy * vec4( -1.0, 0.0, 0.0, 1.0 );", // WebGL port note: Changed sign in W component
  			"vOffset[ 1 ] = texcoord.xyxy + resolution.xyxy * vec4( 1.0, 0.0, 0.0, -1.0 );", // WebGL port note: Changed sign in W component
  		"}",
  
  		"void main() {",
  
  			"vUv = uv;",
  
  			"SMAANeighborhoodBlendingVS( vUv );",
  
  			"gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",
  
  		"}"
  
  	].join("\n"),
  
  	fragmentShader: [
  
  		"uniform sampler2D tDiffuse;",
  		"uniform sampler2D tColor;",
  		"uniform vec2 resolution;",
  
  		"varying vec2 vUv;",
  		"varying vec4 vOffset[ 2 ];",
  
  		"vec4 SMAANeighborhoodBlendingPS( vec2 texcoord, vec4 offset[ 2 ], sampler2D colorTex, sampler2D blendTex ) {",
  			// Fetch the blending weights for current pixel:
  			"vec4 a;",
  			"a.xz = texture2D( blendTex, texcoord ).xz;",
  			"a.y = texture2D( blendTex, offset[ 1 ].zw ).g;",
  			"a.w = texture2D( blendTex, offset[ 1 ].xy ).a;",
  
  			// Is there any blending weight with a value greater than 0.0?
  			"if ( dot(a, vec4( 1.0, 1.0, 1.0, 1.0 )) < 1e-5 ) {",
  				"return texture2D( colorTex, texcoord, 0.0 );",
  			"} else {",
  				// Up to 4 lines can be crossing a pixel (one through each edge). We
  				// favor blending by choosing the line with the maximum weight for each
  				// direction:
  				"vec2 offset;",
  				"offset.x = a.a > a.b ? a.a : -a.b;", // left vs. right
  				"offset.y = a.g > a.r ? -a.g : a.r;", // top vs. bottom // WebGL port note: Changed signs
  
  				// Then we go in the direction that has the maximum weight:
  				"if ( abs( offset.x ) > abs( offset.y )) {", // horizontal vs. vertical
  					"offset.y = 0.0;",
  				"} else {",
  					"offset.x = 0.0;",
  				"}",
  
  				// Fetch the opposite color and lerp by hand:
  				"vec4 C = texture2D( colorTex, texcoord, 0.0 );",
  				"texcoord += sign( offset ) * resolution;",
  				"vec4 Cop = texture2D( colorTex, texcoord, 0.0 );",
  				"float s = abs( offset.x ) > abs( offset.y ) ? abs( offset.x ) : abs( offset.y );",
  
  				// WebGL port note: Added gamma correction
  				"C.xyz = pow(C.xyz, vec3(2.2));",
  				"Cop.xyz = pow(Cop.xyz, vec3(2.2));",
  				"vec4 mixed = mix(C, Cop, s);",
  				"mixed.xyz = pow(mixed.xyz, vec3(1.0 / 2.2));",
  
  				"return mixed;",
  			"}",
  		"}",
  
  		"void main() {",
  
  			"gl_FragColor = SMAANeighborhoodBlendingPS( vUv, vOffset, tColor, tDiffuse );",
  
  		"}"
  
  	].join("\n")
  
  } ];
  