/**
 * @author alteredq / http://alteredqualia.com/
 *
 */

THREE.ShaderTerrain = {

	/* -------------------------------------------------------------------------
	//	Dynamic terrain shader
	//		- Blinn-Phong
	//		- height + normal + diffuse1 + diffuse2 + specular + detail maps
	//		- point, directional and hemisphere lights (use with "lights: true" material option)
	//		- shadow maps receiving
	 ------------------------------------------------------------------------- */

	'terrain' : {

		uniforms: THREE.UniformsUtils.merge( [

			THREE.UniformsLib[ "fog" ],
			THREE.UniformsLib[ "lights" ],

			{

				"enableDiffuse1": { value: 0 },
				"enableDiffuse2": { value: 0 },
				"enableSpecular": { value: 0 },
				"enableReflection": { value: 0 },

				"tDiffuse1": { value: null },
				"tDiffuse2": { value: null },
				"tDetail": { value: null },
				"tNormal": { value: null },
				"tSpecular": { value: null },
				"tDisplacement": { value: null },

				"uNormalScale": { value: 1.0 },

				"uDisplacementBias": { value: 0.0 },
				"uDisplacementScale": { value: 1.0 },

				"diffuse": { value: new THREE.Color( 0xeeeeee ) },
				"specular": { value: new THREE.Color( 0x111111 ) },
				"shininess": { value: 30 },
				"opacity": { value: 1 },

				"uRepeatBase": { value: new THREE.Vector2( 1, 1 ) },
				"uRepeatOverlay": { value: new THREE.Vector2( 1, 1 ) },

				"uOffset": { value: new THREE.Vector2( 0, 0 ) }

			}

		] ),

		fragmentShader: [

			"uniform vec3 diffuse;",
			"uniform vec3 specular;",
			"uniform float shininess;",
			"uniform float opacity;",

			"uniform bool enableDiffuse1;",
			"uniform bool enableDiffuse2;",
			"uniform bool enableSpecular;",

			"uniform sampler2D tDiffuse1;",
			"uniform sampler2D tDiffuse2;",
			"uniform sampler2D tDetail;",
			"uniform sampler2D tNormal;",
			"uniform sampler2D tSpecular;",
			"uniform sampler2D tDisplacement;",

			"uniform float uNormalScale;",

			"uniform vec2 uRepeatOverlay;",
			"uniform vec2 uRepeatBase;",

			"uniform vec2 uOffset;",

			"varying vec3 vTangent;",
			"varying vec3 vBinormal;",
			"varying vec3 vNormal;",
			"varying vec2 vUv;",

			"varying vec3 vViewPosition;",

			THREE.ShaderChunk[ "common" ],
			THREE.ShaderChunk[ "bsdfs" ],
			THREE.ShaderChunk[ "lights_pars" ],
			THREE.ShaderChunk[ "shadowmap_pars_fragment" ],
			THREE.ShaderChunk[ "fog_pars_fragment" ],

			"float calcLightAttenuation( float lightDistance, float cutoffDistance, float decayExponent ) {",
 				"if ( decayExponent > 0.0 ) {",
 					"return pow( saturate( - lightDistance / cutoffDistance + 1.0 ), decayExponent );",
 				"}",
 				"return 1.0;",
 			"}",

			"void main() {",

				"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 );",

				"vec2 uvOverlay = uRepeatOverlay * vUv + uOffset;",
				"vec2 uvBase = uRepeatBase * vUv;",

				"vec3 normalTex = texture2D( tDetail, uvOverlay ).xyz * 2.0 - 1.0;",
				"normalTex.xy *= uNormalScale;",
				"normalTex = normalize( normalTex );",

				"if( enableDiffuse1 && enableDiffuse2 ) {",

					"vec4 colDiffuse1 = texture2D( tDiffuse1, uvOverlay );",
					"vec4 colDiffuse2 = texture2D( tDiffuse2, uvOverlay );",

					"colDiffuse1 = GammaToLinear( colDiffuse1, float( GAMMA_FACTOR ) );",
					"colDiffuse2 = GammaToLinear( colDiffuse2, float( GAMMA_FACTOR ) );",

					"diffuseColor *= mix ( colDiffuse1, colDiffuse2, 1.0 - texture2D( tDisplacement, uvBase ) );",

				" } else if( enableDiffuse1 ) {",

					"diffuseColor *= texture2D( tDiffuse1, uvOverlay );",

				"} else if( enableDiffuse2 ) {",

					"diffuseColor *= texture2D( tDiffuse2, uvOverlay );",

				"}",

				"if( enableSpecular )",
					"specularTex = texture2D( tSpecular, uvOverlay ).xyz;",

				"mat3 tsb = mat3( vTangent, vBinormal, vNormal );",
				"vec3 finalNormal = tsb * normalTex;",

				"vec3 normal = normalize( finalNormal );",
				"vec3 viewPosition = normalize( vViewPosition );",

				"vec3 totalDiffuseLight = vec3( 0.0 );",
				"vec3 totalSpecularLight = vec3( 0.0 );",

				// point lights

				"#if NUM_POINT_LIGHTS > 0",

					"for ( int i = 0; i < NUM_POINT_LIGHTS; i ++ ) {",

						"vec3 lVector = pointLights[ i ].position + vViewPosition.xyz;",

						"float attenuation = calcLightAttenuation( length( lVector ), pointLights[ i ].distance, pointLights[ i ].decay );",

						"lVector = normalize( lVector );",

						"vec3 pointHalfVector = normalize( lVector + viewPosition );",

						"float pointDotNormalHalf = max( dot( normal, pointHalfVector ), 0.0 );",
						"float pointDiffuseWeight = max( dot( normal, lVector ), 0.0 );",

						"float pointSpecularWeight = specularTex.r * max( pow( pointDotNormalHalf, shininess ), 0.0 );",

						"totalDiffuseLight += attenuation * pointLights[ i ].color * pointDiffuseWeight;",
						"totalSpecularLight += attenuation * pointLights[ i ].color * specular * pointSpecularWeight * pointDiffuseWeight;",

					"}",

				"#endif",

				// directional lights

				"#if NUM_DIR_LIGHTS > 0",

					"vec3 dirDiffuse = vec3( 0.0 );",
					"vec3 dirSpecular = vec3( 0.0 );",

					"for( int i = 0; i < NUM_DIR_LIGHTS; i++ ) {",

						"vec3 dirVector = directionalLights[ i ].direction;",
						"vec3 dirHalfVector = normalize( dirVector + viewPosition );",

						"float dirDotNormalHalf = max( dot( normal, dirHalfVector ), 0.0 );",
						"float dirDiffuseWeight = max( dot( normal, dirVector ), 0.0 );",

						"float dirSpecularWeight = specularTex.r * max( pow( dirDotNormalHalf, shininess ), 0.0 );",

						"totalDiffuseLight += directionalLights[ i ].color * dirDiffuseWeight;",
						"totalSpecularLight += directionalLights[ i ].color * specular * dirSpecularWeight * dirDiffuseWeight;",

					"}",

				"#endif",

				// hemisphere lights

				"#if NUM_HEMI_LIGHTS > 0",

					"vec3 hemiDiffuse  = vec3( 0.0 );",
					"vec3 hemiSpecular = vec3( 0.0 );",

					"for( int i = 0; i < NUM_HEMI_LIGHTS; i ++ ) {",

						"vec3 lVector = hemisphereLightDirection[ i ];",

						// diffuse

						"float dotProduct = dot( normal, lVector );",
						"float hemiDiffuseWeight = 0.5 * dotProduct + 0.5;",

						"totalDiffuseLight += mix( hemisphereLights[ i ].groundColor, hemisphereLights[ i ].skyColor, hemiDiffuseWeight );",

						// specular (sky light)

						"float hemiSpecularWeight = 0.0;",

						"vec3 hemiHalfVectorSky = normalize( lVector + viewPosition );",
						"float hemiDotNormalHalfSky = 0.5 * dot( normal, hemiHalfVectorSky ) + 0.5;",
						"hemiSpecularWeight += specularTex.r * max( pow( hemiDotNormalHalfSky, shininess ), 0.0 );",

						// specular (ground light)

						"vec3 lVectorGround = -lVector;",

						"vec3 hemiHalfVectorGround = normalize( lVectorGround + viewPosition );",
						"float hemiDotNormalHalfGround = 0.5 * dot( normal, hemiHalfVectorGround ) + 0.5;",
						"hemiSpecularWeight += specularTex.r * max( pow( hemiDotNormalHalfGround, shininess ), 0.0 );",

						"totalSpecularLight += specular * mix( hemisphereLights[ i ].groundColor, hemisphereLights[ i ].skyColor, hemiDiffuseWeight ) * hemiSpecularWeight * hemiDiffuseWeight;",

					"}",

				"#endif",

				"outgoingLight += diffuseColor.xyz * ( totalDiffuseLight + ambientLightColor + totalSpecularLight );",

				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 uRepeatBase;",

			"uniform sampler2D tNormal;",

			"#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 vViewPosition;",

			THREE.ShaderChunk[ "shadowmap_pars_vertex" ],

			"void main() {",

				"vNormal = normalize( normalMatrix * normal );",

				// tangent and binormal vectors

				"vTangent = normalize( normalMatrix * tangent.xyz );",

				"vBinormal = cross( vNormal, vTangent ) * tangent.w;",
				"vBinormal = normalize( vBinormal );",

				// texture coordinates

				"vUv = uv;",

				"vec2 uvBase = uv * uRepeatBase;",

				// displacement mapping

				"#ifdef VERTEX_TEXTURES",

					"vec3 dv = texture2D( tDisplacement, uvBase ).xyz;",
					"float df = uDisplacementScale * dv.x + uDisplacementBias;",
					"vec3 displacedPosition = normal * df + position;",

					"vec4 worldPosition = modelMatrix * vec4( displacedPosition, 1.0 );",
					"vec4 mvPosition = modelViewMatrix * vec4( displacedPosition, 1.0 );",

				"#else",

					"vec4 worldPosition = modelMatrix * vec4( position, 1.0 );",
					"vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 );",

				"#endif",

				"gl_Position = projectionMatrix * mvPosition;",

				"vViewPosition = -mvPosition.xyz;",

				"vec3 normalTex = texture2D( tNormal, uvBase ).xyz * 2.0 - 1.0;",
				"vNormal = normalMatrix * normalTex;",

				THREE.ShaderChunk[ "shadowmap_vertex" ],

			"}"

		].join( "\n" )

	}

};
