text: /*
   * @author alteredq / http://alteredqualia.com/
   *
   * Normal map shader
   *  - Blinn-Phong
   *  - normal + diffuse + specular + AO + displacement + reflection + shadow maps
   *  - point and directional lights (use with "lights: true" material option)
   */
  import THREE from 'three';
  
  THREE.NormalDisplacementShader = {
  
    uniforms: THREE.UniformsUtils.merge( [
  
      THREE.UniformsLib[ "fog" ],
      THREE.UniformsLib[ "lights" ],
      THREE.UniformsLib[ "shadowmap" ],
  
      {
  
      "enableAO"          : { type: "i", value: 0 },
      "enableDiffuse"     : { type: "i", value: 0 },
      "enableSpecular"    : { type: "i", value: 0 },
      "enableReflection"  : { type: "i", value: 0 },
      "enableDisplacement": { type: "i", value: 0 },
  
      "tDisplacement": { type: "t", value: null }, // must go first as this is vertex texture
      "tDiffuse"     : { type: "t", value: null },
      "tCube"        : { type: "t", value: null },
      "tNormal"      : { type: "t", value: null },
      "tSpecular"    : { type: "t", value: null },
      "tAO"          : { type: "t", value: null },
  
      "uNormalScale": { type: "v2", value: new THREE.Vector2( 1, 1 ) },
  
      "uDisplacementBias": { type: "f", value: 0.0 },
      "uDisplacementScale": { type: "f", value: 1.0 },
  
      "diffuse": { type: "c", value: new THREE.Color( 0xffffff ) },
      "specular": { type: "c", value: new THREE.Color( 0x111111 ) },
      "shininess": { type: "f", value: 30 },
      "opacity": { type: "f", value: 1 },
  
      "refractionRatio": { type: "f", value: 0.98 },
      "reflectivity": { type: "f", value: 0.5 },
  
      "uOffset" : { type: "v2", value: new THREE.Vector2( 0, 0 ) },
      "uRepeat" : { type: "v2", value: new THREE.Vector2( 1, 1 ) },
  
      "wrapRGB" : { type: "v3", value: new THREE.Vector3( 1, 1, 1 ) }
  
      }
  
    ] ),
  
    fragmentShader: [
  
      "uniform vec3 diffuse;",
      "uniform vec3 specular;",
      "uniform float shininess;",
      "uniform float opacity;",
  
      "uniform bool enableDiffuse;",
      "uniform bool enableSpecular;",
      "uniform bool enableAO;",
      "uniform bool enableReflection;",
  
      "uniform sampler2D tDiffuse;",
      "uniform sampler2D tNormal;",
      "uniform sampler2D tSpecular;",
      "uniform sampler2D tAO;",
  
      "uniform samplerCube tCube;",
  
      "uniform vec2 uNormalScale;",
  
      "uniform float refractionRatio;",
      "uniform float reflectivity;",
  
      "varying vec3 vTangent;",
      "varying vec3 vBinormal;",
      "varying vec3 vNormal;",
      "varying vec2 vUv;",
  
      "uniform vec3 ambientLightColor;",
  
      "#if MAX_DIR_LIGHTS > 0",
  
      " uniform vec3 directionalLightColor[ MAX_DIR_LIGHTS ];",
      " uniform vec3 directionalLightDirection[ MAX_DIR_LIGHTS ];",
  
      "#endif",
  
      "#if MAX_HEMI_LIGHTS > 0",
  
      " uniform vec3 hemisphereLightSkyColor[ MAX_HEMI_LIGHTS ];",
      " uniform vec3 hemisphereLightGroundColor[ MAX_HEMI_LIGHTS ];",
      " uniform vec3 hemisphereLightDirection[ MAX_HEMI_LIGHTS ];",
  
      "#endif",
  
      "#if MAX_POINT_LIGHTS > 0",
  
      " uniform vec3 pointLightColor[ MAX_POINT_LIGHTS ];",
      " uniform vec3 pointLightPosition[ MAX_POINT_LIGHTS ];",
      " uniform float pointLightDistance[ MAX_POINT_LIGHTS ];",
  
      "#endif",
  
      "#if MAX_SPOT_LIGHTS > 0",
  
      " uniform vec3 spotLightColor[ MAX_SPOT_LIGHTS ];",
      " uniform vec3 spotLightPosition[ MAX_SPOT_LIGHTS ];",
      " uniform vec3 spotLightDirection[ MAX_SPOT_LIGHTS ];",
      " uniform float spotLightAngleCos[ MAX_SPOT_LIGHTS ];",
      " uniform float spotLightExponent[ MAX_SPOT_LIGHTS ];",
      " uniform float spotLightDistance[ MAX_SPOT_LIGHTS ];",
  
      "#endif",
  
      "#ifdef WRAP_AROUND",
  
      " uniform vec3 wrapRGB;",
  
      "#endif",
  
      "varying vec3 vWorldPosition;",
      "varying vec3 vViewPosition;",
  
      THREE.ShaderChunk[ "common" ],
      THREE.ShaderChunk[ "shadowmap_pars_fragment" ],
      THREE.ShaderChunk[ "fog_pars_fragment" ],
      THREE.ShaderChunk[ "logdepthbuf_pars_fragment" ],
  
      "void main() {",
        THREE.ShaderChunk[ "logdepthbuf_fragment" ],
  
      " vec3 outgoingLight = vec3( 0.0 );", // outgoing light does not have an alpha, the surface does
      " vec4 diffuseColor = vec4( diffuse, opacity );",
  
      " vec3 specularTex = vec3( 1.0 );",
  
      " vec3 normalTex = texture2D( tNormal, vUv ).xyz * 2.0 - 1.0;",
      " normalTex.xy *= uNormalScale;",
      " normalTex = normalize( normalTex );",
  
      " if( enableDiffuse ) {",
  
      "   #ifdef GAMMA_INPUT",
  
      "     vec4 texelColor = texture2D( tDiffuse, vUv );",
      "     texelColor.xyz *= texelColor.xyz;",
  
      "     diffuseColor *= texelColor;",
  
      "   #else",
  
      "     diffuseColor *= texture2D( tDiffuse, vUv );",
  
      "   #endif",
  
      " }",
  
      " if( enableAO ) {",
  
      "   #ifdef GAMMA_INPUT",
  
      "     vec4 aoColor = texture2D( tAO, vUv );",
      "     aoColor.xyz *= aoColor.xyz;",
  
      "     diffuseColor.rgb *= aoColor.xyz;",
  
      "   #else",
  
      "     diffuseColor.rgb *= texture2D( tAO, vUv ).xyz;",
  
      "   #endif",
  
      " }",
  
      THREE.ShaderChunk[ "alphatest_fragment" ],
  
      " if( enableSpecular )",
      "   specularTex = texture2D( tSpecular, vUv ).xyz;",
  
      " mat3 tsb = mat3( normalize( vTangent ), normalize( vBinormal ), normalize( vNormal ) );",
      " vec3 finalNormal = tsb * normalTex;",
  
      " #ifdef FLIP_SIDED",
  
      "   finalNormal = -finalNormal;",
  
      " #endif",
  
      " vec3 normal = normalize( finalNormal );",
      " vec3 viewPosition = normalize( vViewPosition );",
  
      " vec3 totalDiffuseLight = vec3( 0.0 );",
      " vec3 totalSpecularLight = vec3( 0.0 );",
  
        // point lights
  
      " #if MAX_POINT_LIGHTS > 0",
  
      "   for ( int i = 0; i < MAX_POINT_LIGHTS; i ++ ) {",
  
      "     vec4 lPosition = viewMatrix * vec4( pointLightPosition[ i ], 1.0 );",
      "     vec3 pointVector = lPosition.xyz + vViewPosition.xyz;",
  
      "     float pointDistance = 1.0;",
      "     if ( pointLightDistance[ i ] > 0.0 )",
      "       pointDistance = 1.0 - min( ( length( pointVector ) / pointLightDistance[ i ] ), 1.0 );",
  
      "     pointVector = normalize( pointVector );",
  
            // diffuse
  
      "     #ifdef WRAP_AROUND",
  
      "       float pointDiffuseWeightFull = max( dot( normal, pointVector ), 0.0 );",
      "       float pointDiffuseWeightHalf = max( 0.5 * dot( normal, pointVector ) + 0.5, 0.0 );",
  
      "       vec3 pointDiffuseWeight = mix( vec3( pointDiffuseWeightFull ), vec3( pointDiffuseWeightHalf ), wrapRGB );",
  
      "     #else",
  
      "       float pointDiffuseWeight = max( dot( normal, pointVector ), 0.0 );",
  
      "     #endif",
  
      "     totalDiffuseLight += pointDistance * pointLightColor[ i ] * pointDiffuseWeight;",
  
            // specular
  
      "     vec3 pointHalfVector = normalize( pointVector + viewPosition );",
      "     float pointDotNormalHalf = max( dot( normal, pointHalfVector ), 0.0 );",
      "     float pointSpecularWeight = specularTex.r * max( pow( pointDotNormalHalf, shininess ), 0.0 );",
  
      "     float specularNormalization = ( shininess + 2.0 ) / 8.0;",
  
      "     vec3 schlick = specular + vec3( 1.0 - specular ) * pow( max( 1.0 - dot( pointVector, pointHalfVector ), 0.0 ), 5.0 );",
      "     totalSpecularLight += schlick * pointLightColor[ i ] * pointSpecularWeight * pointDiffuseWeight * pointDistance * specularNormalization;",
  
      "   }",
  
      " #endif",
  
        // spot lights
  
      " #if MAX_SPOT_LIGHTS > 0",
  
      "   for ( int i = 0; i < MAX_SPOT_LIGHTS; i ++ ) {",
  
      "     vec4 lPosition = viewMatrix * vec4( spotLightPosition[ i ], 1.0 );",
      "     vec3 spotVector = lPosition.xyz + vViewPosition.xyz;",
  
      "     float spotDistance = 1.0;",
      "     if ( spotLightDistance[ i ] > 0.0 )",
      "       spotDistance = 1.0 - min( ( length( spotVector ) / spotLightDistance[ i ] ), 1.0 );",
  
      "     spotVector = normalize( spotVector );",
  
      "     float spotEffect = dot( spotLightDirection[ i ], normalize( spotLightPosition[ i ] - vWorldPosition ) );",
  
      "     if ( spotEffect > spotLightAngleCos[ i ] ) {",
  
      "       spotEffect = max( pow( max( spotEffect, 0.0 ), spotLightExponent[ i ] ), 0.0 );",
  
              // diffuse
  
      "       #ifdef WRAP_AROUND",
  
      "         float spotDiffuseWeightFull = max( dot( normal, spotVector ), 0.0 );",
      "         float spotDiffuseWeightHalf = max( 0.5 * dot( normal, spotVector ) + 0.5, 0.0 );",
  
      "         vec3 spotDiffuseWeight = mix( vec3( spotDiffuseWeightFull ), vec3( spotDiffuseWeightHalf ), wrapRGB );",
  
      "       #else",
  
      "         float spotDiffuseWeight = max( dot( normal, spotVector ), 0.0 );",
  
      "       #endif",
  
      "       totalDiffuseLight += spotDistance * spotLightColor[ i ] * spotDiffuseWeight * spotEffect;",
  
              // specular
  
      "       vec3 spotHalfVector = normalize( spotVector + viewPosition );",
      "       float spotDotNormalHalf = max( dot( normal, spotHalfVector ), 0.0 );",
      "       float spotSpecularWeight = specularTex.r * max( pow( spotDotNormalHalf, shininess ), 0.0 );",
  
      "       float specularNormalization = ( shininess + 2.0 ) / 8.0;",
  
      "       vec3 schlick = specular + vec3( 1.0 - specular ) * pow( max( 1.0 - dot( spotVector, spotHalfVector ), 0.0 ), 5.0 );",
      "       totalSpecularLight += schlick * spotLightColor[ i ] * spotSpecularWeight * spotDiffuseWeight * spotDistance * specularNormalization * spotEffect;",
  
      "     }",
  
      "   }",
  
      " #endif",
  
        // directional lights
  
      " #if MAX_DIR_LIGHTS > 0",
  
      "   for( int i = 0; i < MAX_DIR_LIGHTS; i++ ) {",
  
      "     vec4 lDirection = viewMatrix * vec4( directionalLightDirection[ i ], 0.0 );",
      "     vec3 dirVector = normalize( lDirection.xyz );",
  
            // diffuse
  
      "     #ifdef WRAP_AROUND",
  
      "       float directionalLightWeightingFull = max( dot( normal, dirVector ), 0.0 );",
      "       float directionalLightWeightingHalf = max( 0.5 * dot( normal, dirVector ) + 0.5, 0.0 );",
  
      "       vec3 dirDiffuseWeight = mix( vec3( directionalLightWeightingFull ), vec3( directionalLightWeightingHalf ), wrapRGB );",
  
      "     #else",
  
      "       float dirDiffuseWeight = max( dot( normal, dirVector ), 0.0 );",
  
      "     #endif",
  
      "     totalDiffuseLight += directionalLightColor[ i ] * dirDiffuseWeight;",
  
            // specular
  
      "     vec3 dirHalfVector = normalize( dirVector + viewPosition );",
      "     float dirDotNormalHalf = max( dot( normal, dirHalfVector ), 0.0 );",
      "     float dirSpecularWeight = specularTex.r * max( pow( dirDotNormalHalf, shininess ), 0.0 );",
  
      "     float specularNormalization = ( shininess + 2.0 ) / 8.0;",
  
      "     vec3 schlick = specular + vec3( 1.0 - specular ) * pow( max( 1.0 - dot( dirVector, dirHalfVector ), 0.0 ), 5.0 );",
      "     totalSpecularLight += schlick * directionalLightColor[ i ] * dirSpecularWeight * dirDiffuseWeight * specularNormalization;",
  
      "   }",
  
      " #endif",
  
        // hemisphere lights
  
      " #if MAX_HEMI_LIGHTS > 0",
  
      "   for( int i = 0; i < MAX_HEMI_LIGHTS; i ++ ) {",
  
      "     vec4 lDirection = viewMatrix * vec4( hemisphereLightDirection[ i ], 0.0 );",
      "     vec3 lVector = normalize( lDirection.xyz );",
  
            // diffuse
  
      "     float dotProduct = dot( normal, lVector );",
      "     float hemiDiffuseWeight = 0.5 * dotProduct + 0.5;",
  
      "     vec3 hemiColor = mix( hemisphereLightGroundColor[ i ], hemisphereLightSkyColor[ i ], hemiDiffuseWeight );",
  
      "     totalDiffuseLight += hemiColor;",
  
            // specular (sky light)
  
  
      "     vec3 hemiHalfVectorSky = normalize( lVector + viewPosition );",
      "     float hemiDotNormalHalfSky = 0.5 * dot( normal, hemiHalfVectorSky ) + 0.5;",
      "     float hemiSpecularWeightSky = specularTex.r * max( pow( max( hemiDotNormalHalfSky, 0.0 ), shininess ), 0.0 );",
  
            // specular (ground light)
  
      "     vec3 lVectorGround = -lVector;",
  
      "     vec3 hemiHalfVectorGround = normalize( lVectorGround + viewPosition );",
      "     float hemiDotNormalHalfGround = 0.5 * dot( normal, hemiHalfVectorGround ) + 0.5;",
      "     float hemiSpecularWeightGround = specularTex.r * max( pow( max( hemiDotNormalHalfGround, 0.0 ), shininess ), 0.0 );",
  
      "     float dotProductGround = dot( normal, lVectorGround );",
  
      "     float specularNormalization = ( shininess + 2.0 ) / 8.0;",
  
      "     vec3 schlickSky = specular + vec3( 1.0 - specular ) * pow( max( 1.0 - dot( lVector, hemiHalfVectorSky ), 0.0 ), 5.0 );",
      "     vec3 schlickGround = specular + vec3( 1.0 - specular ) * pow( max( 1.0 - dot( lVectorGround, hemiHalfVectorGround ), 0.0 ), 5.0 );",
      "     totalSpecularLight += hemiColor * specularNormalization * ( schlickSky * hemiSpecularWeightSky * max( dotProduct, 0.0 ) + schlickGround * hemiSpecularWeightGround * max( dotProductGround, 0.0 ) );",
  
      "   }",
  
      " #endif",
  
      " #ifdef METAL",
  
      "   outgoingLight += diffuseColor.xyz * ( totalDiffuseLight + ambientLightColor + totalSpecularLight );",
  
      " #else",
  
      "   outgoingLight += diffuseColor.xyz * ( totalDiffuseLight + ambientLightColor ) + totalSpecularLight;",
  
      " #endif",
  
      " if ( enableReflection ) {",
  
      "   vec3 cameraToVertex = normalize( vWorldPosition - cameraPosition );",
  
      "   #ifdef ENVMAP_MODE_REFLECTION",
  
      "     vec3 vReflect = reflect( cameraToVertex, normal );",
  
      "   #else",
  
      "     vec3 vReflect = refract( cameraToVertex, normal, refractionRatio );",
  
      "   #endif",
  
      "   vec4 cubeColor = textureCube( tCube, vec3( -vReflect.x, vReflect.yz ) );",
  
      "   #ifdef GAMMA_INPUT",
  
      "     cubeColor.xyz *= cubeColor.xyz;",
  
      "   #endif",
  
      "   outgoingLight = mix( outgoingLight, cubeColor.xyz, specularTex.r * reflectivity );",
  
      " }",
  
        THREE.ShaderChunk[ "shadowmap_fragment" ],
        THREE.ShaderChunk[ "linear_to_gamma_fragment" ],
        THREE.ShaderChunk[ "fog_fragment" ],
  
      " gl_FragColor = vec4( outgoingLight, diffuseColor.a );", // TODO, this should be pre-multiplied to allow for bright highlights on very transparent objects
  
      "}"
  
    ].join("\n"),
  
    vertexShader: [
  
      "attribute vec4 tangent;",
  
      "uniform vec2 uOffset;",
      "uniform vec2 uRepeat;",
  
      "uniform bool enableDisplacement;",
  
      "#ifdef VERTEX_TEXTURES",
  
      " uniform sampler2D tDisplacement;",
      " uniform float uDisplacementScale;",
      " uniform float uDisplacementBias;",
  
      "#endif",
  
      "varying vec3 vTangent;",
      "varying vec3 vBinormal;",
      "varying vec3 vNormal;",
      "varying vec2 vUv;",
  
      "varying vec3 vWorldPosition;",
      "varying vec3 vViewPosition;",
  
      THREE.ShaderChunk[ "skinning_pars_vertex" ],
      THREE.ShaderChunk[ "shadowmap_pars_vertex" ],
      THREE.ShaderChunk[ "logdepthbuf_pars_vertex" ],
  
      "void main() {",
  
        THREE.ShaderChunk[ "skinbase_vertex" ],
        THREE.ShaderChunk[ "skinnormal_vertex" ],
  
        // normal, tangent and binormal vectors
  
      " #ifdef USE_SKINNING",
  
      "   vNormal = normalize( normalMatrix * skinnedNormal.xyz );",
  
      "   vec4 skinnedTangent = skinMatrix * vec4( tangent.xyz, 0.0 );",
      "   vTangent = normalize( normalMatrix * skinnedTangent.xyz );",
  
      " #else",
  
      "   vNormal = normalize( normalMatrix * normal );",
      "   vTangent = normalize( normalMatrix * tangent.xyz );",
  
      " #endif",
  
      " vBinormal = normalize( cross( vNormal, vTangent ) * tangent.w );",
  
      " vUv = uv * uRepeat + uOffset;",
  
        // displacement mapping
  
      " vec3 displacedPosition;",
  
      " #ifdef VERTEX_TEXTURES",
  
      "   if ( enableDisplacement ) {",
  
      "     vec3 dv = texture2D( tDisplacement, uv ).xyz;",
      "     float df = uDisplacementScale * dv.x + uDisplacementBias;",
      "     displacedPosition = position + normalize( normal ) * df;",
  
      "   } else {",
  
      "     #ifdef USE_SKINNING",
  
      "       vec4 skinVertex = bindMatrix * vec4( position, 1.0 );",
  
      "       vec4 skinned = vec4( 0.0 );",
      "       skinned += boneMatX * skinVertex * skinWeight.x;",
      "       skinned += boneMatY * skinVertex * skinWeight.y;",
      "       skinned += boneMatZ * skinVertex * skinWeight.z;",
      "       skinned += boneMatW * skinVertex * skinWeight.w;",
      "       skinned  = bindMatrixInverse * skinned;",
  
      "       displacedPosition = skinned.xyz;",
  
      "     #else",
  
      "       displacedPosition = position;",
  
      "     #endif",
  
      "   }",
  
      " #else",
  
      "   #ifdef USE_SKINNING",
  
      "     vec4 skinVertex = bindMatrix * vec4( position, 1.0 );",
  
      "     vec4 skinned = vec4( 0.0 );",
      "     skinned += boneMatX * skinVertex * skinWeight.x;",
      "     skinned += boneMatY * skinVertex * skinWeight.y;",
      "     skinned += boneMatZ * skinVertex * skinWeight.z;",
      "     skinned += boneMatW * skinVertex * skinWeight.w;",
      "     skinned  = bindMatrixInverse * skinned;",
  
      "     displacedPosition = skinned.xyz;",
  
      "   #else",
  
      "     displacedPosition = position;",
  
      "   #endif",
  
      " #endif",
  
        //
  
      " vec4 mvPosition = modelViewMatrix * vec4( displacedPosition, 1.0 );",
      " vec4 worldPosition = modelMatrix * vec4( displacedPosition, 1.0 );",
  
      " gl_Position = projectionMatrix * mvPosition;",
  
        THREE.ShaderChunk[ "logdepthbuf_vertex" ],
  
        //
  
      " vWorldPosition = worldPosition.xyz;",
      " vViewPosition = -mvPosition.xyz;",
  
        // shadows
  
      " #ifdef USE_SHADOWMAP",
  
      "   for( int i = 0; i < MAX_SHADOWS; i ++ ) {",
  
      "     vShadowCoord[ i ] = shadowMatrix[ i ] * worldPosition;",
  
      "   }",
  
      " #endif",
  
      "}"
  
    ].join("\n")
  
  };
  