import { LinearFilter, LinearMipmapLinearFilter, LinearMipmapNearestFilter, NearestFilter, NearestMipmapLinearFilter, NearestMipmapNearestFilter, RGBAFormat, RGB_ETC1_Format, DepthFormat, DepthStencilFormat, UnsignedShortType, UnsignedIntType, UnsignedInt248Type, FloatType, HalfFloatType, MirroredRepeatWrapping, ClampToEdgeWrapping, RepeatWrapping, UnsignedByteType, _SRGBAFormat, NoColorSpace, LinearSRGBColorSpace, NeverCompare, AlwaysCompare, LessCompare, LessEqualCompare, EqualCompare, GreaterEqualCompare, GreaterCompare, NotEqualCompare, SRGBTransfer, LinearTransfer } from '../../constants.js';
import * as MathUtils from '../../math/MathUtils.js';
import { ImageUtils } from '../../extras/ImageUtils.js';
import { createElementNS } from '../../utils.js';
import { ColorManagement } from '../../math/ColorManagement.js';

function WebGLTextures( _gl, extensions, state, properties, capabilities, utils, info ) {

	const isWebGL2 = capabilities.isWebGL2;
	const multisampledRTTExt = extensions.has( 'WEBGL_multisampled_render_to_texture' ) ? extensions.get( 'WEBGL_multisampled_render_to_texture' ) : null;
	const supportsInvalidateFramebuffer = typeof navigator === 'undefined' ? false : /OculusBrowser/g.test( navigator.userAgent );

	const _videoTextures = new WeakMap();
	let _canvas;

	const _sources = new WeakMap(); // maps WebglTexture objects to instances of Source

	// cordova iOS (as of 5.0) still uses UIWebView, which provides OffscreenCanvas,
	// also OffscreenCanvas.getContext("webgl"), but not OffscreenCanvas.getContext("2d")!
	// Some implementations may only implement OffscreenCanvas partially (e.g. lacking 2d).

	let useOffscreenCanvas = false;

	try {

		useOffscreenCanvas = typeof OffscreenCanvas !== 'undefined'
			// eslint-disable-next-line compat/compat
			&& ( new OffscreenCanvas( 1, 1 ).getContext( '2d' ) ) !== null;

	} catch ( err ) {

		// Ignore any errors

	}

	function createCanvas( width, height ) {

		// Use OffscreenCanvas when available. Specially needed in web workers

		return useOffscreenCanvas ?
			// eslint-disable-next-line compat/compat
			new OffscreenCanvas( width, height ) : createElementNS( 'canvas' );

	}

	function resizeImage( image, needsPowerOfTwo, needsNewCanvas, maxSize ) {

		let scale = 1;

		// handle case if texture exceeds max size

		if ( image.width > maxSize || image.height > maxSize ) {

			scale = maxSize / Math.max( image.width, image.height );

		}

		// only perform resize if necessary

		if ( scale < 1 || needsPowerOfTwo === true ) {

			// only perform resize for certain image types

			if ( ( typeof HTMLImageElement !== 'undefined' && image instanceof HTMLImageElement ) ||
				( typeof HTMLCanvasElement !== 'undefined' && image instanceof HTMLCanvasElement ) ||
				( typeof ImageBitmap !== 'undefined' && image instanceof ImageBitmap ) ) {

				const floor = needsPowerOfTwo ? MathUtils.floorPowerOfTwo : Math.floor;

				const width = floor( scale * image.width );
				const height = floor( scale * image.height );

				if ( _canvas === undefined ) _canvas = createCanvas( width, height );

				// cube textures can't reuse the same canvas

				const canvas = needsNewCanvas ? createCanvas( width, height ) : _canvas;

				canvas.width = width;
				canvas.height = height;

				const context = canvas.getContext( '2d' );
				context.drawImage( image, 0, 0, width, height );

				console.warn( 'THREE.WebGLRenderer: Texture has been resized from (' + image.width + 'x' + image.height + ') to (' + width + 'x' + height + ').' );

				return canvas;

			} else {

				if ( 'data' in image ) {

					console.warn( 'THREE.WebGLRenderer: Image in DataTexture is too big (' + image.width + 'x' + image.height + ').' );

				}

				return image;

			}

		}

		return image;

	}

	function isPowerOfTwo( image ) {

		return MathUtils.isPowerOfTwo( image.width ) && MathUtils.isPowerOfTwo( image.height );

	}

	function textureNeedsPowerOfTwo( texture ) {

		if ( isWebGL2 ) return false;

		return ( texture.wrapS !== ClampToEdgeWrapping || texture.wrapT !== ClampToEdgeWrapping ) ||
			( texture.minFilter !== NearestFilter && texture.minFilter !== LinearFilter );

	}

	function textureNeedsGenerateMipmaps( texture, supportsMips ) {

		return texture.generateMipmaps && supportsMips &&
			texture.minFilter !== NearestFilter && texture.minFilter !== LinearFilter;

	}

	function generateMipmap( target ) {

		_gl.generateMipmap( target );

	}

	function getInternalFormat( internalFormatName, glFormat, glType, colorSpace, forceLinearTransfer = false ) {

		if ( isWebGL2 === false ) return glFormat;

		if ( internalFormatName !== null ) {

			if ( _gl[ internalFormatName ] !== undefined ) return _gl[ internalFormatName ];

			console.warn( 'THREE.WebGLRenderer: Attempt to use non-existing WebGL internal format \'' + internalFormatName + '\'' );

		}

		let internalFormat = glFormat;

		if ( glFormat === _gl.RED ) {

			if ( glType === _gl.FLOAT ) internalFormat = _gl.R32F;
			if ( glType === _gl.HALF_FLOAT ) internalFormat = _gl.R16F;
			if ( glType === _gl.UNSIGNED_BYTE ) internalFormat = _gl.R8;

		}

		if ( glFormat === _gl.RED_INTEGER ) {

			if ( glType === _gl.UNSIGNED_BYTE ) internalFormat = _gl.R8UI;
			if ( glType === _gl.UNSIGNED_SHORT ) internalFormat = _gl.R16UI;
			if ( glType === _gl.UNSIGNED_INT ) internalFormat = _gl.R32UI;
			if ( glType === _gl.BYTE ) internalFormat = _gl.R8I;
			if ( glType === _gl.SHORT ) internalFormat = _gl.R16I;
			if ( glType === _gl.INT ) internalFormat = _gl.R32I;

		}

		if ( glFormat === _gl.RG ) {

			if ( glType === _gl.FLOAT ) internalFormat = _gl.RG32F;
			if ( glType === _gl.HALF_FLOAT ) internalFormat = _gl.RG16F;
			if ( glType === _gl.UNSIGNED_BYTE ) internalFormat = _gl.RG8;

		}

		if ( glFormat === _gl.RGBA ) {

			const transfer = forceLinearTransfer ? LinearTransfer : ColorManagement.getTransfer( colorSpace );

			if ( glType === _gl.FLOAT ) internalFormat = _gl.RGBA32F;
			if ( glType === _gl.HALF_FLOAT ) internalFormat = _gl.RGBA16F;
			if ( glType === _gl.UNSIGNED_BYTE ) internalFormat = ( transfer === SRGBTransfer ) ? _gl.SRGB8_ALPHA8 : _gl.RGBA8;
			if ( glType === _gl.UNSIGNED_SHORT_4_4_4_4 ) internalFormat = _gl.RGBA4;
			if ( glType === _gl.UNSIGNED_SHORT_5_5_5_1 ) internalFormat = _gl.RGB5_A1;

		}

		if ( internalFormat === _gl.R16F || internalFormat === _gl.R32F ||
			internalFormat === _gl.RG16F || internalFormat === _gl.RG32F ||
			internalFormat === _gl.RGBA16F || internalFormat === _gl.RGBA32F ) {

			extensions.get( 'EXT_color_buffer_float' );

		}

		return internalFormat;

	}

	function getMipLevels( texture, image, supportsMips ) {

		if ( textureNeedsGenerateMipmaps( texture, supportsMips ) === true || ( texture.isFramebufferTexture && texture.minFilter !== NearestFilter && texture.minFilter !== LinearFilter ) ) {

			return Math.log2( Math.max( image.width, image.height ) ) + 1;

		} else if ( texture.mipmaps !== undefined && texture.mipmaps.length > 0 ) {

			// user-defined mipmaps

			return texture.mipmaps.length;

		} else if ( texture.isCompressedTexture && Array.isArray( texture.image ) ) {

			return image.mipmaps.length;

		} else {

			// texture without mipmaps (only base level)

			return 1;

		}

	}

	// Fallback filters for non-power-of-2 textures

	function filterFallback( f ) {

		if ( f === NearestFilter || f === NearestMipmapNearestFilter || f === NearestMipmapLinearFilter ) {

			return _gl.NEAREST;

		}

		return _gl.LINEAR;

	}

	//

	function onTextureDispose( event ) {

		const texture = event.target;

		texture.removeEventListener( 'dispose', onTextureDispose );

		deallocateTexture( texture );

		if ( texture.isVideoTexture ) {

			_videoTextures.delete( texture );

		}

	}

	function onRenderTargetDispose( event ) {

		const renderTarget = event.target;

		renderTarget.removeEventListener( 'dispose', onRenderTargetDispose );

		deallocateRenderTarget( renderTarget );

	}

	//

	function deallocateTexture( texture ) {

		const textureProperties = properties.get( texture );

		if ( textureProperties.__webglInit === undefined ) return;

		// check if it's necessary to remove the WebGLTexture object

		const source = texture.source;
		const webglTextures = _sources.get( source );

		if ( webglTextures ) {

			const webglTexture = webglTextures[ textureProperties.__cacheKey ];
			webglTexture.usedTimes --;

			// the WebGLTexture object is not used anymore, remove it

			if ( webglTexture.usedTimes === 0 ) {

				deleteTexture( texture );

			}

			// remove the weak map entry if no WebGLTexture uses the source anymore

			if ( Object.keys( webglTextures ).length === 0 ) {

				_sources.delete( source );

			}

		}

		properties.remove( texture );

	}

	function deleteTexture( texture ) {

		const textureProperties = properties.get( texture );
		_gl.deleteTexture( textureProperties.__webglTexture );

		const source = texture.source;
		const webglTextures = _sources.get( source );
		delete webglTextures[ textureProperties.__cacheKey ];

		info.memory.textures --;

	}

	function deallocateRenderTarget( renderTarget ) {

		const texture = renderTarget.texture;

		const renderTargetProperties = properties.get( renderTarget );
		const textureProperties = properties.get( texture );

		if ( textureProperties.__webglTexture !== undefined ) {

			_gl.deleteTexture( textureProperties.__webglTexture );

			info.memory.textures --;

		}

		if ( renderTarget.depthTexture ) {

			renderTarget.depthTexture.dispose();

		}

		if ( renderTarget.isWebGLCubeRenderTarget ) {

			for ( let i = 0; i < 6; i ++ ) {

				if ( Array.isArray( renderTargetProperties.__webglFramebuffer[ i ] ) ) {

					for ( let level = 0; level < renderTargetProperties.__webglFramebuffer[ i ].length; level ++ ) _gl.deleteFramebuffer( renderTargetProperties.__webglFramebuffer[ i ][ level ] );

				} else {

					_gl.deleteFramebuffer( renderTargetProperties.__webglFramebuffer[ i ] );

				}

				if ( renderTargetProperties.__webglDepthbuffer ) _gl.deleteRenderbuffer( renderTargetProperties.__webglDepthbuffer[ i ] );

			}

		} else {

			if ( Array.isArray( renderTargetProperties.__webglFramebuffer ) ) {

				for ( let level = 0; level < renderTargetProperties.__webglFramebuffer.length; level ++ ) _gl.deleteFramebuffer( renderTargetProperties.__webglFramebuffer[ level ] );

			} else {

				_gl.deleteFramebuffer( renderTargetProperties.__webglFramebuffer );

			}

			if ( renderTargetProperties.__webglDepthbuffer ) _gl.deleteRenderbuffer( renderTargetProperties.__webglDepthbuffer );
			if ( renderTargetProperties.__webglMultisampledFramebuffer ) _gl.deleteFramebuffer( renderTargetProperties.__webglMultisampledFramebuffer );

			if ( renderTargetProperties.__webglColorRenderbuffer ) {

				for ( let i = 0; i < renderTargetProperties.__webglColorRenderbuffer.length; i ++ ) {

					if ( renderTargetProperties.__webglColorRenderbuffer[ i ] ) _gl.deleteRenderbuffer( renderTargetProperties.__webglColorRenderbuffer[ i ] );

				}

			}

			if ( renderTargetProperties.__webglDepthRenderbuffer ) _gl.deleteRenderbuffer( renderTargetProperties.__webglDepthRenderbuffer );

		}

		if ( renderTarget.isWebGLMultipleRenderTargets ) {

			for ( let i = 0, il = texture.length; i < il; i ++ ) {

				const attachmentProperties = properties.get( texture[ i ] );

				if ( attachmentProperties.__webglTexture ) {

					_gl.deleteTexture( attachmentProperties.__webglTexture );

					info.memory.textures --;

				}

				properties.remove( texture[ i ] );

			}

		}

		properties.remove( texture );
		properties.remove( renderTarget );

	}

	//

	let textureUnits = 0;

	function resetTextureUnits() {

		textureUnits = 0;

	}

	function allocateTextureUnit() {

		const textureUnit = textureUnits;

		if ( textureUnit >= capabilities.maxTextures ) {

			console.warn( 'THREE.WebGLTextures: Trying to use ' + textureUnit + ' texture units while this GPU supports only ' + capabilities.maxTextures );

		}

		textureUnits += 1;

		return textureUnit;

	}

	function getTextureCacheKey( texture ) {

		const array = [];

		array.push( texture.wrapS );
		array.push( texture.wrapT );
		array.push( texture.wrapR || 0 );
		array.push( texture.magFilter );
		array.push( texture.minFilter );
		array.push( texture.anisotropy );
		array.push( texture.internalFormat );
		array.push( texture.format );
		array.push( texture.type );
		array.push( texture.generateMipmaps );
		array.push( texture.premultiplyAlpha );
		array.push( texture.flipY );
		array.push( texture.unpackAlignment );
		array.push( texture.colorSpace );

		return array.join();

	}

	//

	function setTexture2D( texture, slot ) {

		const textureProperties = properties.get( texture );

		if ( texture.isVideoTexture ) updateVideoTexture( texture );

		if ( texture.isRenderTargetTexture === false && texture.version > 0 && textureProperties.__version !== texture.version ) {

			const image = texture.image;

			if ( image === null ) {

				console.warn( 'THREE.WebGLRenderer: Texture marked for update but no image data found.' );

			} else if ( image.complete === false ) {

				console.warn( 'THREE.WebGLRenderer: Texture marked for update but image is incomplete' );

			} else {

				uploadTexture( textureProperties, texture, slot );
				return;

			}

		}

		state.bindTexture( _gl.TEXTURE_2D, textureProperties.__webglTexture, _gl.TEXTURE0 + slot );

	}

	function setTexture2DArray( texture, slot ) {

		const textureProperties = properties.get( texture );

		if ( texture.version > 0 && textureProperties.__version !== texture.version ) {

			uploadTexture( textureProperties, texture, slot );
			return;

		}

		state.bindTexture( _gl.TEXTURE_2D_ARRAY, textureProperties.__webglTexture, _gl.TEXTURE0 + slot );

	}

	function setTexture3D( texture, slot ) {

		const textureProperties = properties.get( texture );

		if ( texture.version > 0 && textureProperties.__version !== texture.version ) {

			uploadTexture( textureProperties, texture, slot );
			return;

		}

		state.bindTexture( _gl.TEXTURE_3D, textureProperties.__webglTexture, _gl.TEXTURE0 + slot );

	}

	function setTextureCube( texture, slot ) {

		const textureProperties = properties.get( texture );

		if ( texture.version > 0 && textureProperties.__version !== texture.version ) {

			uploadCubeTexture( textureProperties, texture, slot );
			return;

		}

		state.bindTexture( _gl.TEXTURE_CUBE_MAP, textureProperties.__webglTexture, _gl.TEXTURE0 + slot );

	}

	const wrappingToGL = {
		[ RepeatWrapping ]: _gl.REPEAT,
		[ ClampToEdgeWrapping ]: _gl.CLAMP_TO_EDGE,
		[ MirroredRepeatWrapping ]: _gl.MIRRORED_REPEAT
	};

	const filterToGL = {
		[ NearestFilter ]: _gl.NEAREST,
		[ NearestMipmapNearestFilter ]: _gl.NEAREST_MIPMAP_NEAREST,
		[ NearestMipmapLinearFilter ]: _gl.NEAREST_MIPMAP_LINEAR,

		[ LinearFilter ]: _gl.LINEAR,
		[ LinearMipmapNearestFilter ]: _gl.LINEAR_MIPMAP_NEAREST,
		[ LinearMipmapLinearFilter ]: _gl.LINEAR_MIPMAP_LINEAR
	};

	const compareToGL = {
		[ NeverCompare ]: _gl.NEVER,
		[ AlwaysCompare ]: _gl.ALWAYS,
		[ LessCompare ]: _gl.LESS,
		[ LessEqualCompare ]: _gl.LEQUAL,
		[ EqualCompare ]: _gl.EQUAL,
		[ GreaterEqualCompare ]: _gl.GEQUAL,
		[ GreaterCompare ]: _gl.GREATER,
		[ NotEqualCompare ]: _gl.NOTEQUAL
	};

	function setTextureParameters( textureType, texture, supportsMips ) {

		if ( supportsMips ) {

			_gl.texParameteri( textureType, _gl.TEXTURE_WRAP_S, wrappingToGL[ texture.wrapS ] );
			_gl.texParameteri( textureType, _gl.TEXTURE_WRAP_T, wrappingToGL[ texture.wrapT ] );

			if ( textureType === _gl.TEXTURE_3D || textureType === _gl.TEXTURE_2D_ARRAY ) {

				_gl.texParameteri( textureType, _gl.TEXTURE_WRAP_R, wrappingToGL[ texture.wrapR ] );

			}

			_gl.texParameteri( textureType, _gl.TEXTURE_MAG_FILTER, filterToGL[ texture.magFilter ] );
			_gl.texParameteri( textureType, _gl.TEXTURE_MIN_FILTER, filterToGL[ texture.minFilter ] );

		} else {

			_gl.texParameteri( textureType, _gl.TEXTURE_WRAP_S, _gl.CLAMP_TO_EDGE );
			_gl.texParameteri( textureType, _gl.TEXTURE_WRAP_T, _gl.CLAMP_TO_EDGE );

			if ( textureType === _gl.TEXTURE_3D || textureType === _gl.TEXTURE_2D_ARRAY ) {

				_gl.texParameteri( textureType, _gl.TEXTURE_WRAP_R, _gl.CLAMP_TO_EDGE );

			}

			if ( texture.wrapS !== ClampToEdgeWrapping || texture.wrapT !== ClampToEdgeWrapping ) {

				console.warn( 'THREE.WebGLRenderer: Texture is not power of two. Texture.wrapS and Texture.wrapT should be set to THREE.ClampToEdgeWrapping.' );

			}

			_gl.texParameteri( textureType, _gl.TEXTURE_MAG_FILTER, filterFallback( texture.magFilter ) );
			_gl.texParameteri( textureType, _gl.TEXTURE_MIN_FILTER, filterFallback( texture.minFilter ) );

			if ( texture.minFilter !== NearestFilter && texture.minFilter !== LinearFilter ) {

				console.warn( 'THREE.WebGLRenderer: Texture is not power of two. Texture.minFilter should be set to THREE.NearestFilter or THREE.LinearFilter.' );

			}

		}

		if ( texture.compareFunction ) {

			_gl.texParameteri( textureType, _gl.TEXTURE_COMPARE_MODE, _gl.COMPARE_REF_TO_TEXTURE );
			_gl.texParameteri( textureType, _gl.TEXTURE_COMPARE_FUNC, compareToGL[ texture.compareFunction ] );

		}

		if ( extensions.has( 'EXT_texture_filter_anisotropic' ) === true ) {

			const extension = extensions.get( 'EXT_texture_filter_anisotropic' );

			if ( texture.magFilter === NearestFilter ) return;
			if ( texture.minFilter !== NearestMipmapLinearFilter && texture.minFilter !== LinearMipmapLinearFilter ) return;
			if ( texture.type === FloatType && extensions.has( 'OES_texture_float_linear' ) === false ) return; // verify extension for WebGL 1 and WebGL 2
			if ( isWebGL2 === false && ( texture.type === HalfFloatType && extensions.has( 'OES_texture_half_float_linear' ) === false ) ) return; // verify extension for WebGL 1 only

			if ( texture.anisotropy > 1 || properties.get( texture ).__currentAnisotropy ) {

				_gl.texParameterf( textureType, extension.TEXTURE_MAX_ANISOTROPY_EXT, Math.min( texture.anisotropy, capabilities.getMaxAnisotropy() ) );
				properties.get( texture ).__currentAnisotropy = texture.anisotropy;

			}

		}

	}

	function initTexture( textureProperties, texture ) {

		let forceUpload = false;

		if ( textureProperties.__webglInit === undefined ) {

			textureProperties.__webglInit = true;

			texture.addEventListener( 'dispose', onTextureDispose );

		}

		// create Source <-> WebGLTextures mapping if necessary

		const source = texture.source;
		let webglTextures = _sources.get( source );

		if ( webglTextures === undefined ) {

			webglTextures = {};
			_sources.set( source, webglTextures );

		}

		// check if there is already a WebGLTexture object for the given texture parameters

		const textureCacheKey = getTextureCacheKey( texture );

		if ( textureCacheKey !== textureProperties.__cacheKey ) {

			// if not, create a new instance of WebGLTexture

			if ( webglTextures[ textureCacheKey ] === undefined ) {

				// create new entry

				webglTextures[ textureCacheKey ] = {
					texture: _gl.createTexture(),
					usedTimes: 0
				};

				info.memory.textures ++;

				// when a new instance of WebGLTexture was created, a texture upload is required
				// even if the image contents are identical

				forceUpload = true;

			}

			webglTextures[ textureCacheKey ].usedTimes ++;

			// every time the texture cache key changes, it's necessary to check if an instance of
			// WebGLTexture can be deleted in order to avoid a memory leak.

			const webglTexture = webglTextures[ textureProperties.__cacheKey ];

			if ( webglTexture !== undefined ) {

				webglTextures[ textureProperties.__cacheKey ].usedTimes --;

				if ( webglTexture.usedTimes === 0 ) {

					deleteTexture( texture );

				}

			}

			// store references to cache key and WebGLTexture object

			textureProperties.__cacheKey = textureCacheKey;
			textureProperties.__webglTexture = webglTextures[ textureCacheKey ].texture;

		}

		return forceUpload;

	}

	function uploadTexture( textureProperties, texture, slot ) {

		let textureType = _gl.TEXTURE_2D;

		if ( texture.isDataArrayTexture || texture.isCompressedArrayTexture ) textureType = _gl.TEXTURE_2D_ARRAY;
		if ( texture.isData3DTexture ) textureType = _gl.TEXTURE_3D;

		const forceUpload = initTexture( textureProperties, texture );
		const source = texture.source;

		state.bindTexture( textureType, textureProperties.__webglTexture, _gl.TEXTURE0 + slot );

		const sourceProperties = properties.get( source );

		if ( source.version !== sourceProperties.__version || forceUpload === true ) {

			state.activeTexture( _gl.TEXTURE0 + slot );

			const workingPrimaries = ColorManagement.getPrimaries( ColorManagement.workingColorSpace );
			const texturePrimaries = texture.colorSpace === NoColorSpace ? null : ColorManagement.getPrimaries( texture.colorSpace );
			const unpackConversion = texture.colorSpace === NoColorSpace || workingPrimaries === texturePrimaries ? _gl.NONE : _gl.BROWSER_DEFAULT_WEBGL;

			_gl.pixelStorei( _gl.UNPACK_FLIP_Y_WEBGL, texture.flipY );
			_gl.pixelStorei( _gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, texture.premultiplyAlpha );
			_gl.pixelStorei( _gl.UNPACK_ALIGNMENT, texture.unpackAlignment );
			_gl.pixelStorei( _gl.UNPACK_COLORSPACE_CONVERSION_WEBGL, unpackConversion );

			const needsPowerOfTwo = textureNeedsPowerOfTwo( texture ) && isPowerOfTwo( texture.image ) === false;
			let image = resizeImage( texture.image, needsPowerOfTwo, false, capabilities.maxTextureSize );
			image = verifyColorSpace( texture, image );

			const supportsMips = isPowerOfTwo( image ) || isWebGL2,
				glFormat = utils.convert( texture.format, texture.colorSpace );

			let glType = utils.convert( texture.type ),
				glInternalFormat = getInternalFormat( texture.internalFormat, glFormat, glType, texture.colorSpace, texture.isVideoTexture );

			setTextureParameters( textureType, texture, supportsMips );

			let mipmap;
			const mipmaps = texture.mipmaps;

			const useTexStorage = ( isWebGL2 && texture.isVideoTexture !== true && glInternalFormat !== RGB_ETC1_Format );
			const allocateMemory = ( sourceProperties.__version === undefined ) || ( forceUpload === true );
			const levels = getMipLevels( texture, image, supportsMips );

			if ( texture.isDepthTexture ) {

				// populate depth texture with dummy data

				glInternalFormat = _gl.DEPTH_COMPONENT;

				if ( isWebGL2 ) {

					if ( texture.type === FloatType ) {

						glInternalFormat = _gl.DEPTH_COMPONENT32F;

					} else if ( texture.type === UnsignedIntType ) {

						glInternalFormat = _gl.DEPTH_COMPONENT24;

					} else if ( texture.type === UnsignedInt248Type ) {

						glInternalFormat = _gl.DEPTH24_STENCIL8;

					} else {

						glInternalFormat = _gl.DEPTH_COMPONENT16; // WebGL2 requires sized internalformat for glTexImage2D

					}

				} else {

					if ( texture.type === FloatType ) {

						console.error( 'WebGLRenderer: Floating point depth texture requires WebGL2.' );

					}

				}

				// validation checks for WebGL 1

				if ( texture.format === DepthFormat && glInternalFormat === _gl.DEPTH_COMPONENT ) {

					// The error INVALID_OPERATION is generated by texImage2D if format and internalformat are
					// DEPTH_COMPONENT and type is not UNSIGNED_SHORT or UNSIGNED_INT
					// (https://www.khronos.org/registry/webgl/extensions/WEBGL_depth_texture/)
					if ( texture.type !== UnsignedShortType && texture.type !== UnsignedIntType ) {

						console.warn( 'THREE.WebGLRenderer: Use UnsignedShortType or UnsignedIntType for DepthFormat DepthTexture.' );

						texture.type = UnsignedIntType;
						glType = utils.convert( texture.type );

					}

				}

				if ( texture.format === DepthStencilFormat && glInternalFormat === _gl.DEPTH_COMPONENT ) {

					// Depth stencil textures need the DEPTH_STENCIL internal format
					// (https://www.khronos.org/registry/webgl/extensions/WEBGL_depth_texture/)
					glInternalFormat = _gl.DEPTH_STENCIL;

					// The error INVALID_OPERATION is generated by texImage2D if format and internalformat are
					// DEPTH_STENCIL and type is not UNSIGNED_INT_24_8_WEBGL.
					// (https://www.khronos.org/registry/webgl/extensions/WEBGL_depth_texture/)
					if ( texture.type !== UnsignedInt248Type ) {

						console.warn( 'THREE.WebGLRenderer: Use UnsignedInt248Type for DepthStencilFormat DepthTexture.' );

						texture.type = UnsignedInt248Type;
						glType = utils.convert( texture.type );

					}

				}

				//

				if ( allocateMemory ) {

					if ( useTexStorage ) {

						state.texStorage2D( _gl.TEXTURE_2D, 1, glInternalFormat, image.width, image.height );

					} else {

						state.texImage2D( _gl.TEXTURE_2D, 0, glInternalFormat, image.width, image.height, 0, glFormat, glType, null );

					}

				}

			} else if ( texture.isDataTexture ) {

				// use manually created mipmaps if available
				// if there are no manual mipmaps
				// set 0 level mipmap and then use GL to generate other mipmap levels

				if ( mipmaps.length > 0 && supportsMips ) {

					if ( useTexStorage && allocateMemory ) {

						state.texStorage2D( _gl.TEXTURE_2D, levels, glInternalFormat, mipmaps[ 0 ].width, mipmaps[ 0 ].height );

					}

					for ( let i = 0, il = mipmaps.length; i < il; i ++ ) {

						mipmap = mipmaps[ i ];

						if ( useTexStorage ) {

							state.texSubImage2D( _gl.TEXTURE_2D, i, 0, 0, mipmap.width, mipmap.height, glFormat, glType, mipmap.data );

						} else {

							state.texImage2D( _gl.TEXTURE_2D, i, glInternalFormat, mipmap.width, mipmap.height, 0, glFormat, glType, mipmap.data );

						}

					}

					texture.generateMipmaps = false;

				} else {

					if ( useTexStorage ) {

						if ( allocateMemory ) {

							state.texStorage2D( _gl.TEXTURE_2D, levels, glInternalFormat, image.width, image.height );

						}

						state.texSubImage2D( _gl.TEXTURE_2D, 0, 0, 0, image.width, image.height, glFormat, glType, image.data );

					} else {

						state.texImage2D( _gl.TEXTURE_2D, 0, glInternalFormat, image.width, image.height, 0, glFormat, glType, image.data );

					}

				}

			} else if ( texture.isCompressedTexture ) {

				if ( texture.isCompressedArrayTexture ) {

					if ( useTexStorage && allocateMemory ) {

						state.texStorage3D( _gl.TEXTURE_2D_ARRAY, levels, glInternalFormat, mipmaps[ 0 ].width, mipmaps[ 0 ].height, image.depth );

					}

					for ( let i = 0, il = mipmaps.length; i < il; i ++ ) {

						mipmap = mipmaps[ i ];

						if ( texture.format !== RGBAFormat ) {

							if ( glFormat !== null ) {

								if ( useTexStorage ) {

									state.compressedTexSubImage3D( _gl.TEXTURE_2D_ARRAY, i, 0, 0, 0, mipmap.width, mipmap.height, image.depth, glFormat, mipmap.data, 0, 0 );

								} else {

									state.compressedTexImage3D( _gl.TEXTURE_2D_ARRAY, i, glInternalFormat, mipmap.width, mipmap.height, image.depth, 0, mipmap.data, 0, 0 );

								}

							} else {

								console.warn( 'THREE.WebGLRenderer: Attempt to load unsupported compressed texture format in .uploadTexture()' );

							}

						} else {

							if ( useTexStorage ) {

								state.texSubImage3D( _gl.TEXTURE_2D_ARRAY, i, 0, 0, 0, mipmap.width, mipmap.height, image.depth, glFormat, glType, mipmap.data );

							} else {

								state.texImage3D( _gl.TEXTURE_2D_ARRAY, i, glInternalFormat, mipmap.width, mipmap.height, image.depth, 0, glFormat, glType, mipmap.data );

							}

						}

					}

				} else {

					if ( useTexStorage && allocateMemory ) {

						state.texStorage2D( _gl.TEXTURE_2D, levels, glInternalFormat, mipmaps[ 0 ].width, mipmaps[ 0 ].height );

					}

					for ( let i = 0, il = mipmaps.length; i < il; i ++ ) {

						mipmap = mipmaps[ i ];

						if ( texture.format !== RGBAFormat ) {

							if ( glFormat !== null ) {

								if ( useTexStorage ) {

									state.compressedTexSubImage2D( _gl.TEXTURE_2D, i, 0, 0, mipmap.width, mipmap.height, glFormat, mipmap.data );

								} else {

									state.compressedTexImage2D( _gl.TEXTURE_2D, i, glInternalFormat, mipmap.width, mipmap.height, 0, mipmap.data );

								}

							} else {

								console.warn( 'THREE.WebGLRenderer: Attempt to load unsupported compressed texture format in .uploadTexture()' );

							}

						} else {

							if ( useTexStorage ) {

								state.texSubImage2D( _gl.TEXTURE_2D, i, 0, 0, mipmap.width, mipmap.height, glFormat, glType, mipmap.data );

							} else {

								state.texImage2D( _gl.TEXTURE_2D, i, glInternalFormat, mipmap.width, mipmap.height, 0, glFormat, glType, mipmap.data );

							}

						}

					}

				}

			} else if ( texture.isDataArrayTexture ) {

				if ( useTexStorage ) {

					if ( allocateMemory ) {

						state.texStorage3D( _gl.TEXTURE_2D_ARRAY, levels, glInternalFormat, image.width, image.height, image.depth );

					}

					state.texSubImage3D( _gl.TEXTURE_2D_ARRAY, 0, 0, 0, 0, image.width, image.height, image.depth, glFormat, glType, image.data );

				} else {

					state.texImage3D( _gl.TEXTURE_2D_ARRAY, 0, glInternalFormat, image.width, image.height, image.depth, 0, glFormat, glType, image.data );

				}

			} else if ( texture.isData3DTexture ) {

				if ( useTexStorage ) {

					if ( allocateMemory ) {

						state.texStorage3D( _gl.TEXTURE_3D, levels, glInternalFormat, image.width, image.height, image.depth );

					}

					state.texSubImage3D( _gl.TEXTURE_3D, 0, 0, 0, 0, image.width, image.height, image.depth, glFormat, glType, image.data );

				} else {

					state.texImage3D( _gl.TEXTURE_3D, 0, glInternalFormat, image.width, image.height, image.depth, 0, glFormat, glType, image.data );

				}

			} else if ( texture.isFramebufferTexture ) {

				if ( allocateMemory ) {

					if ( useTexStorage ) {

						state.texStorage2D( _gl.TEXTURE_2D, levels, glInternalFormat, image.width, image.height );

					} else {

						let width = image.width, height = image.height;

						for ( let i = 0; i < levels; i ++ ) {

							state.texImage2D( _gl.TEXTURE_2D, i, glInternalFormat, width, height, 0, glFormat, glType, null );

							width >>= 1;
							height >>= 1;

						}

					}

				}

			} else {

				// regular Texture (image, video, canvas)

				// use manually created mipmaps if available
				// if there are no manual mipmaps
				// set 0 level mipmap and then use GL to generate other mipmap levels

				if ( mipmaps.length > 0 && supportsMips ) {

					if ( useTexStorage && allocateMemory ) {

						state.texStorage2D( _gl.TEXTURE_2D, levels, glInternalFormat, mipmaps[ 0 ].width, mipmaps[ 0 ].height );

					}

					for ( let i = 0, il = mipmaps.length; i < il; i ++ ) {

						mipmap = mipmaps[ i ];

						if ( useTexStorage ) {

							state.texSubImage2D( _gl.TEXTURE_2D, i, 0, 0, glFormat, glType, mipmap );

						} else {

							state.texImage2D( _gl.TEXTURE_2D, i, glInternalFormat, glFormat, glType, mipmap );

						}

					}

					texture.generateMipmaps = false;

				} else {

					if ( useTexStorage ) {

						if ( allocateMemory ) {

							state.texStorage2D( _gl.TEXTURE_2D, levels, glInternalFormat, image.width, image.height );

						}

						state.texSubImage2D( _gl.TEXTURE_2D, 0, 0, 0, glFormat, glType, image );

					} else {

						state.texImage2D( _gl.TEXTURE_2D, 0, glInternalFormat, glFormat, glType, image );

					}

				}

			}

			if ( textureNeedsGenerateMipmaps( texture, supportsMips ) ) {

				generateMipmap( textureType );

			}

			sourceProperties.__version = source.version;

			if ( texture.onUpdate ) texture.onUpdate( texture );

		}

		textureProperties.__version = texture.version;

	}

	function uploadCubeTexture( textureProperties, texture, slot ) {

		if ( texture.image.length !== 6 ) return;

		const forceUpload = initTexture( textureProperties, texture );
		const source = texture.source;

		state.bindTexture( _gl.TEXTURE_CUBE_MAP, textureProperties.__webglTexture, _gl.TEXTURE0 + slot );

		const sourceProperties = properties.get( source );

		if ( source.version !== sourceProperties.__version || forceUpload === true ) {

			state.activeTexture( _gl.TEXTURE0 + slot );

			const workingPrimaries = ColorManagement.getPrimaries( ColorManagement.workingColorSpace );
			const texturePrimaries = texture.colorSpace === NoColorSpace ? null : ColorManagement.getPrimaries( texture.colorSpace );
			const unpackConversion = texture.colorSpace === NoColorSpace || workingPrimaries === texturePrimaries ? _gl.NONE : _gl.BROWSER_DEFAULT_WEBGL;

			_gl.pixelStorei( _gl.UNPACK_FLIP_Y_WEBGL, texture.flipY );
			_gl.pixelStorei( _gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, texture.premultiplyAlpha );
			_gl.pixelStorei( _gl.UNPACK_ALIGNMENT, texture.unpackAlignment );
			_gl.pixelStorei( _gl.UNPACK_COLORSPACE_CONVERSION_WEBGL, unpackConversion );

			const isCompressed = ( texture.isCompressedTexture || texture.image[ 0 ].isCompressedTexture );
			const isDataTexture = ( texture.image[ 0 ] && texture.image[ 0 ].isDataTexture );

			const cubeImage = [];

			for ( let i = 0; i < 6; i ++ ) {

				if ( ! isCompressed && ! isDataTexture ) {

					cubeImage[ i ] = resizeImage( texture.image[ i ], false, true, capabilities.maxCubemapSize );

				} else {

					cubeImage[ i ] = isDataTexture ? texture.image[ i ].image : texture.image[ i ];

				}

				cubeImage[ i ] = verifyColorSpace( texture, cubeImage[ i ] );

			}

			const image = cubeImage[ 0 ],
				supportsMips = isPowerOfTwo( image ) || isWebGL2,
				glFormat = utils.convert( texture.format, texture.colorSpace ),
				glType = utils.convert( texture.type ),
				glInternalFormat = getInternalFormat( texture.internalFormat, glFormat, glType, texture.colorSpace );

			const useTexStorage = ( isWebGL2 && texture.isVideoTexture !== true );
			const allocateMemory = ( sourceProperties.__version === undefined ) || ( forceUpload === true );
			let levels = getMipLevels( texture, image, supportsMips );

			setTextureParameters( _gl.TEXTURE_CUBE_MAP, texture, supportsMips );

			let mipmaps;

			if ( isCompressed ) {

				if ( useTexStorage && allocateMemory ) {

					state.texStorage2D( _gl.TEXTURE_CUBE_MAP, levels, glInternalFormat, image.width, image.height );

				}

				for ( let i = 0; i < 6; i ++ ) {

					mipmaps = cubeImage[ i ].mipmaps;

					for ( let j = 0; j < mipmaps.length; j ++ ) {

						const mipmap = mipmaps[ j ];

						if ( texture.format !== RGBAFormat ) {

							if ( glFormat !== null ) {

								if ( useTexStorage ) {

									state.compressedTexSubImage2D( _gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, j, 0, 0, mipmap.width, mipmap.height, glFormat, mipmap.data );

								} else {

									state.compressedTexImage2D( _gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, j, glInternalFormat, mipmap.width, mipmap.height, 0, mipmap.data );

								}

							} else {

								console.warn( 'THREE.WebGLRenderer: Attempt to load unsupported compressed texture format in .setTextureCube()' );

							}

						} else {

							if ( useTexStorage ) {

								state.texSubImage2D( _gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, j, 0, 0, mipmap.width, mipmap.height, glFormat, glType, mipmap.data );

							} else {

								state.texImage2D( _gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, j, glInternalFormat, mipmap.width, mipmap.height, 0, glFormat, glType, mipmap.data );

							}

						}

					}

				}

			} else {

				mipmaps = texture.mipmaps;

				if ( useTexStorage && allocateMemory ) {

					// TODO: Uniformly handle mipmap definitions
					// Normal textures and compressed cube textures define base level + mips with their mipmap array
					// Uncompressed cube textures use their mipmap array only for mips (no base level)

					if ( mipmaps.length > 0 ) levels ++;

					state.texStorage2D( _gl.TEXTURE_CUBE_MAP, levels, glInternalFormat, cubeImage[ 0 ].width, cubeImage[ 0 ].height );

				}

				for ( let i = 0; i < 6; i ++ ) {

					if ( isDataTexture ) {

						if ( useTexStorage ) {

							state.texSubImage2D( _gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, 0, 0, cubeImage[ i ].width, cubeImage[ i ].height, glFormat, glType, cubeImage[ i ].data );

						} else {

							state.texImage2D( _gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, glInternalFormat, cubeImage[ i ].width, cubeImage[ i ].height, 0, glFormat, glType, cubeImage[ i ].data );

						}

						for ( let j = 0; j < mipmaps.length; j ++ ) {

							const mipmap = mipmaps[ j ];
							const mipmapImage = mipmap.image[ i ].image;

							if ( useTexStorage ) {

								state.texSubImage2D( _gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, j + 1, 0, 0, mipmapImage.width, mipmapImage.height, glFormat, glType, mipmapImage.data );

							} else {

								state.texImage2D( _gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, j + 1, glInternalFormat, mipmapImage.width, mipmapImage.height, 0, glFormat, glType, mipmapImage.data );

							}

						}

					} else {

						if ( useTexStorage ) {

							state.texSubImage2D( _gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, 0, 0, glFormat, glType, cubeImage[ i ] );

						} else {

							state.texImage2D( _gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, glInternalFormat, glFormat, glType, cubeImage[ i ] );

						}

						for ( let j = 0; j < mipmaps.length; j ++ ) {

							const mipmap = mipmaps[ j ];

							if ( useTexStorage ) {

								state.texSubImage2D( _gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, j + 1, 0, 0, glFormat, glType, mipmap.image[ i ] );

							} else {

								state.texImage2D( _gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, j + 1, glInternalFormat, glFormat, glType, mipmap.image[ i ] );

							}

						}

					}

				}

			}

			if ( textureNeedsGenerateMipmaps( texture, supportsMips ) ) {

				// We assume images for cube map have the same size.
				generateMipmap( _gl.TEXTURE_CUBE_MAP );

			}

			sourceProperties.__version = source.version;

			if ( texture.onUpdate ) texture.onUpdate( texture );

		}

		textureProperties.__version = texture.version;

	}

	// Render targets

	// Setup storage for target texture and bind it to correct framebuffer
	function setupFrameBufferTexture( framebuffer, renderTarget, texture, attachment, textureTarget, level ) {

		const glFormat = utils.convert( texture.format, texture.colorSpace );
		const glType = utils.convert( texture.type );
		const glInternalFormat = getInternalFormat( texture.internalFormat, glFormat, glType, texture.colorSpace );
		const renderTargetProperties = properties.get( renderTarget );

		if ( ! renderTargetProperties.__hasExternalTextures ) {

			const width = Math.max( 1, renderTarget.width >> level );
			const height = Math.max( 1, renderTarget.height >> level );

			if ( textureTarget === _gl.TEXTURE_3D || textureTarget === _gl.TEXTURE_2D_ARRAY ) {

				state.texImage3D( textureTarget, level, glInternalFormat, width, height, renderTarget.depth, 0, glFormat, glType, null );

			} else {

				state.texImage2D( textureTarget, level, glInternalFormat, width, height, 0, glFormat, glType, null );

			}

		}

		state.bindFramebuffer( _gl.FRAMEBUFFER, framebuffer );

		if ( useMultisampledRTT( renderTarget ) ) {

			multisampledRTTExt.framebufferTexture2DMultisampleEXT( _gl.FRAMEBUFFER, attachment, textureTarget, properties.get( texture ).__webglTexture, 0, getRenderTargetSamples( renderTarget ) );

		} else if ( textureTarget === _gl.TEXTURE_2D || ( textureTarget >= _gl.TEXTURE_CUBE_MAP_POSITIVE_X && textureTarget <= _gl.TEXTURE_CUBE_MAP_NEGATIVE_Z ) ) { // see #24753

			_gl.framebufferTexture2D( _gl.FRAMEBUFFER, attachment, textureTarget, properties.get( texture ).__webglTexture, level );

		}

		state.bindFramebuffer( _gl.FRAMEBUFFER, null );

	}


	// Setup storage for internal depth/stencil buffers and bind to correct framebuffer
	function setupRenderBufferStorage( renderbuffer, renderTarget, isMultisample ) {

		_gl.bindRenderbuffer( _gl.RENDERBUFFER, renderbuffer );

		if ( renderTarget.depthBuffer && ! renderTarget.stencilBuffer ) {

			let glInternalFormat = ( isWebGL2 === true ) ? _gl.DEPTH_COMPONENT24 : _gl.DEPTH_COMPONENT16;

			if ( isMultisample || useMultisampledRTT( renderTarget ) ) {

				const depthTexture = renderTarget.depthTexture;

				if ( depthTexture && depthTexture.isDepthTexture ) {

					if ( depthTexture.type === FloatType ) {

						glInternalFormat = _gl.DEPTH_COMPONENT32F;

					} else if ( depthTexture.type === UnsignedIntType ) {

						glInternalFormat = _gl.DEPTH_COMPONENT24;

					}

				}

				const samples = getRenderTargetSamples( renderTarget );

				if ( useMultisampledRTT( renderTarget ) ) {

					multisampledRTTExt.renderbufferStorageMultisampleEXT( _gl.RENDERBUFFER, samples, glInternalFormat, renderTarget.width, renderTarget.height );

				} else {

					_gl.renderbufferStorageMultisample( _gl.RENDERBUFFER, samples, glInternalFormat, renderTarget.width, renderTarget.height );

				}

			} else {

				_gl.renderbufferStorage( _gl.RENDERBUFFER, glInternalFormat, renderTarget.width, renderTarget.height );

			}

			_gl.framebufferRenderbuffer( _gl.FRAMEBUFFER, _gl.DEPTH_ATTACHMENT, _gl.RENDERBUFFER, renderbuffer );

		} else if ( renderTarget.depthBuffer && renderTarget.stencilBuffer ) {

			const samples = getRenderTargetSamples( renderTarget );

			if ( isMultisample && useMultisampledRTT( renderTarget ) === false ) {

				_gl.renderbufferStorageMultisample( _gl.RENDERBUFFER, samples, _gl.DEPTH24_STENCIL8, renderTarget.width, renderTarget.height );

			} else if ( useMultisampledRTT( renderTarget ) ) {

				multisampledRTTExt.renderbufferStorageMultisampleEXT( _gl.RENDERBUFFER, samples, _gl.DEPTH24_STENCIL8, renderTarget.width, renderTarget.height );

			} else {

				_gl.renderbufferStorage( _gl.RENDERBUFFER, _gl.DEPTH_STENCIL, renderTarget.width, renderTarget.height );

			}


			_gl.framebufferRenderbuffer( _gl.FRAMEBUFFER, _gl.DEPTH_STENCIL_ATTACHMENT, _gl.RENDERBUFFER, renderbuffer );

		} else {

			const textures = renderTarget.isWebGLMultipleRenderTargets === true ? renderTarget.texture : [ renderTarget.texture ];

			for ( let i = 0; i < textures.length; i ++ ) {

				const texture = textures[ i ];

				const glFormat = utils.convert( texture.format, texture.colorSpace );
				const glType = utils.convert( texture.type );
				const glInternalFormat = getInternalFormat( texture.internalFormat, glFormat, glType, texture.colorSpace );
				const samples = getRenderTargetSamples( renderTarget );

				if ( isMultisample && useMultisampledRTT( renderTarget ) === false ) {

					_gl.renderbufferStorageMultisample( _gl.RENDERBUFFER, samples, glInternalFormat, renderTarget.width, renderTarget.height );

				} else if ( useMultisampledRTT( renderTarget ) ) {

					multisampledRTTExt.renderbufferStorageMultisampleEXT( _gl.RENDERBUFFER, samples, glInternalFormat, renderTarget.width, renderTarget.height );

				} else {

					_gl.renderbufferStorage( _gl.RENDERBUFFER, glInternalFormat, renderTarget.width, renderTarget.height );

				}

			}

		}

		_gl.bindRenderbuffer( _gl.RENDERBUFFER, null );

	}

	// Setup resources for a Depth Texture for a FBO (needs an extension)
	function setupDepthTexture( framebuffer, renderTarget ) {

		const isCube = ( renderTarget && renderTarget.isWebGLCubeRenderTarget );
		if ( isCube ) throw new Error( 'Depth Texture with cube render targets is not supported' );

		state.bindFramebuffer( _gl.FRAMEBUFFER, framebuffer );

		if ( ! ( renderTarget.depthTexture && renderTarget.depthTexture.isDepthTexture ) ) {

			throw new Error( 'renderTarget.depthTexture must be an instance of THREE.DepthTexture' );

		}

		// upload an empty depth texture with framebuffer size
		if ( ! properties.get( renderTarget.depthTexture ).__webglTexture ||
				renderTarget.depthTexture.image.width !== renderTarget.width ||
				renderTarget.depthTexture.image.height !== renderTarget.height ) {

			renderTarget.depthTexture.image.width = renderTarget.width;
			renderTarget.depthTexture.image.height = renderTarget.height;
			renderTarget.depthTexture.needsUpdate = true;

		}

		setTexture2D( renderTarget.depthTexture, 0 );

		const webglDepthTexture = properties.get( renderTarget.depthTexture ).__webglTexture;
		const samples = getRenderTargetSamples( renderTarget );

		if ( renderTarget.depthTexture.format === DepthFormat ) {

			if ( useMultisampledRTT( renderTarget ) ) {

				multisampledRTTExt.framebufferTexture2DMultisampleEXT( _gl.FRAMEBUFFER, _gl.DEPTH_ATTACHMENT, _gl.TEXTURE_2D, webglDepthTexture, 0, samples );

			} else {

				_gl.framebufferTexture2D( _gl.FRAMEBUFFER, _gl.DEPTH_ATTACHMENT, _gl.TEXTURE_2D, webglDepthTexture, 0 );

			}

		} else if ( renderTarget.depthTexture.format === DepthStencilFormat ) {

			if ( useMultisampledRTT( renderTarget ) ) {

				multisampledRTTExt.framebufferTexture2DMultisampleEXT( _gl.FRAMEBUFFER, _gl.DEPTH_STENCIL_ATTACHMENT, _gl.TEXTURE_2D, webglDepthTexture, 0, samples );

			} else {

				_gl.framebufferTexture2D( _gl.FRAMEBUFFER, _gl.DEPTH_STENCIL_ATTACHMENT, _gl.TEXTURE_2D, webglDepthTexture, 0 );

			}

		} else {

			throw new Error( 'Unknown depthTexture format' );

		}

	}

	// Setup GL resources for a non-texture depth buffer
	function setupDepthRenderbuffer( renderTarget ) {

		const renderTargetProperties = properties.get( renderTarget );
		const isCube = ( renderTarget.isWebGLCubeRenderTarget === true );

		if ( renderTarget.depthTexture && ! renderTargetProperties.__autoAllocateDepthBuffer ) {

			if ( isCube ) throw new Error( 'target.depthTexture not supported in Cube render targets' );

			setupDepthTexture( renderTargetProperties.__webglFramebuffer, renderTarget );

		} else {

			if ( isCube ) {

				renderTargetProperties.__webglDepthbuffer = [];

				for ( let i = 0; i < 6; i ++ ) {

					state.bindFramebuffer( _gl.FRAMEBUFFER, renderTargetProperties.__webglFramebuffer[ i ] );
					renderTargetProperties.__webglDepthbuffer[ i ] = _gl.createRenderbuffer();
					setupRenderBufferStorage( renderTargetProperties.__webglDepthbuffer[ i ], renderTarget, false );

				}

			} else {

				state.bindFramebuffer( _gl.FRAMEBUFFER, renderTargetProperties.__webglFramebuffer );
				renderTargetProperties.__webglDepthbuffer = _gl.createRenderbuffer();
				setupRenderBufferStorage( renderTargetProperties.__webglDepthbuffer, renderTarget, false );

			}

		}

		state.bindFramebuffer( _gl.FRAMEBUFFER, null );

	}

	// rebind framebuffer with external textures
	function rebindTextures( renderTarget, colorTexture, depthTexture ) {

		const renderTargetProperties = properties.get( renderTarget );

		if ( colorTexture !== undefined ) {

			setupFrameBufferTexture( renderTargetProperties.__webglFramebuffer, renderTarget, renderTarget.texture, _gl.COLOR_ATTACHMENT0, _gl.TEXTURE_2D, 0 );

		}

		if ( depthTexture !== undefined ) {

			setupDepthRenderbuffer( renderTarget );

		}

	}

	// Set up GL resources for the render target
	function setupRenderTarget( renderTarget ) {

		const texture = renderTarget.texture;

		const renderTargetProperties = properties.get( renderTarget );
		const textureProperties = properties.get( texture );

		renderTarget.addEventListener( 'dispose', onRenderTargetDispose );

		if ( renderTarget.isWebGLMultipleRenderTargets !== true ) {

			if ( textureProperties.__webglTexture === undefined ) {

				textureProperties.__webglTexture = _gl.createTexture();

			}

			textureProperties.__version = texture.version;
			info.memory.textures ++;

		}

		const isCube = ( renderTarget.isWebGLCubeRenderTarget === true );
		const isMultipleRenderTargets = ( renderTarget.isWebGLMultipleRenderTargets === true );
		const supportsMips = isPowerOfTwo( renderTarget ) || isWebGL2;

		// Setup framebuffer

		if ( isCube ) {

			renderTargetProperties.__webglFramebuffer = [];

			for ( let i = 0; i < 6; i ++ ) {

				if ( isWebGL2 && texture.mipmaps && texture.mipmaps.length > 0 ) {

					renderTargetProperties.__webglFramebuffer[ i ] = [];

					for ( let level = 0; level < texture.mipmaps.length; level ++ ) {

						renderTargetProperties.__webglFramebuffer[ i ][ level ] = _gl.createFramebuffer();

					}

				} else {

					renderTargetProperties.__webglFramebuffer[ i ] = _gl.createFramebuffer();

				}

			}

		} else {

			if ( isWebGL2 && texture.mipmaps && texture.mipmaps.length > 0 ) {

				renderTargetProperties.__webglFramebuffer = [];

				for ( let level = 0; level < texture.mipmaps.length; level ++ ) {

					renderTargetProperties.__webglFramebuffer[ level ] = _gl.createFramebuffer();

				}

			} else {

				renderTargetProperties.__webglFramebuffer = _gl.createFramebuffer();

			}

			if ( isMultipleRenderTargets ) {

				if ( capabilities.drawBuffers ) {

					const textures = renderTarget.texture;

					for ( let i = 0, il = textures.length; i < il; i ++ ) {

						const attachmentProperties = properties.get( textures[ i ] );

						if ( attachmentProperties.__webglTexture === undefined ) {

							attachmentProperties.__webglTexture = _gl.createTexture();

							info.memory.textures ++;

						}

					}

				} else {

					console.warn( 'THREE.WebGLRenderer: WebGLMultipleRenderTargets can only be used with WebGL2 or WEBGL_draw_buffers extension.' );

				}

			}

			if ( ( isWebGL2 && renderTarget.samples > 0 ) && useMultisampledRTT( renderTarget ) === false ) {

				const textures = isMultipleRenderTargets ? texture : [ texture ];

				renderTargetProperties.__webglMultisampledFramebuffer = _gl.createFramebuffer();
				renderTargetProperties.__webglColorRenderbuffer = [];

				state.bindFramebuffer( _gl.FRAMEBUFFER, renderTargetProperties.__webglMultisampledFramebuffer );

				for ( let i = 0; i < textures.length; i ++ ) {

					const texture = textures[ i ];
					renderTargetProperties.__webglColorRenderbuffer[ i ] = _gl.createRenderbuffer();

					_gl.bindRenderbuffer( _gl.RENDERBUFFER, renderTargetProperties.__webglColorRenderbuffer[ i ] );

					const glFormat = utils.convert( texture.format, texture.colorSpace );
					const glType = utils.convert( texture.type );
					const glInternalFormat = getInternalFormat( texture.internalFormat, glFormat, glType, texture.colorSpace, renderTarget.isXRRenderTarget === true );
					const samples = getRenderTargetSamples( renderTarget );
					_gl.renderbufferStorageMultisample( _gl.RENDERBUFFER, samples, glInternalFormat, renderTarget.width, renderTarget.height );

					_gl.framebufferRenderbuffer( _gl.FRAMEBUFFER, _gl.COLOR_ATTACHMENT0 + i, _gl.RENDERBUFFER, renderTargetProperties.__webglColorRenderbuffer[ i ] );

				}

				_gl.bindRenderbuffer( _gl.RENDERBUFFER, null );

				if ( renderTarget.depthBuffer ) {

					renderTargetProperties.__webglDepthRenderbuffer = _gl.createRenderbuffer();
					setupRenderBufferStorage( renderTargetProperties.__webglDepthRenderbuffer, renderTarget, true );

				}

				state.bindFramebuffer( _gl.FRAMEBUFFER, null );

			}

		}

		// Setup color buffer

		if ( isCube ) {

			state.bindTexture( _gl.TEXTURE_CUBE_MAP, textureProperties.__webglTexture );
			setTextureParameters( _gl.TEXTURE_CUBE_MAP, texture, supportsMips );

			for ( let i = 0; i < 6; i ++ ) {

				if ( isWebGL2 && texture.mipmaps && texture.mipmaps.length > 0 ) {

					for ( let level = 0; level < texture.mipmaps.length; level ++ ) {

						setupFrameBufferTexture( renderTargetProperties.__webglFramebuffer[ i ][ level ], renderTarget, texture, _gl.COLOR_ATTACHMENT0, _gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, level );

					}

				} else {

					setupFrameBufferTexture( renderTargetProperties.__webglFramebuffer[ i ], renderTarget, texture, _gl.COLOR_ATTACHMENT0, _gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, 0 );

				}

			}

			if ( textureNeedsGenerateMipmaps( texture, supportsMips ) ) {

				generateMipmap( _gl.TEXTURE_CUBE_MAP );

			}

			state.unbindTexture();

		} else if ( isMultipleRenderTargets ) {

			const textures = renderTarget.texture;

			for ( let i = 0, il = textures.length; i < il; i ++ ) {

				const attachment = textures[ i ];
				const attachmentProperties = properties.get( attachment );

				state.bindTexture( _gl.TEXTURE_2D, attachmentProperties.__webglTexture );
				setTextureParameters( _gl.TEXTURE_2D, attachment, supportsMips );
				setupFrameBufferTexture( renderTargetProperties.__webglFramebuffer, renderTarget, attachment, _gl.COLOR_ATTACHMENT0 + i, _gl.TEXTURE_2D, 0 );

				if ( textureNeedsGenerateMipmaps( attachment, supportsMips ) ) {

					generateMipmap( _gl.TEXTURE_2D );

				}

			}

			state.unbindTexture();

		} else {

			let glTextureType = _gl.TEXTURE_2D;

			if ( renderTarget.isWebGL3DRenderTarget || renderTarget.isWebGLArrayRenderTarget ) {

				if ( isWebGL2 ) {

					glTextureType = renderTarget.isWebGL3DRenderTarget ? _gl.TEXTURE_3D : _gl.TEXTURE_2D_ARRAY;

				} else {

					console.error( 'THREE.WebGLTextures: THREE.Data3DTexture and THREE.DataArrayTexture only supported with WebGL2.' );

				}

			}

			state.bindTexture( glTextureType, textureProperties.__webglTexture );
			setTextureParameters( glTextureType, texture, supportsMips );

			if ( isWebGL2 && texture.mipmaps && texture.mipmaps.length > 0 ) {

				for ( let level = 0; level < texture.mipmaps.length; level ++ ) {

					setupFrameBufferTexture( renderTargetProperties.__webglFramebuffer[ level ], renderTarget, texture, _gl.COLOR_ATTACHMENT0, glTextureType, level );

				}

			} else {

				setupFrameBufferTexture( renderTargetProperties.__webglFramebuffer, renderTarget, texture, _gl.COLOR_ATTACHMENT0, glTextureType, 0 );

			}

			if ( textureNeedsGenerateMipmaps( texture, supportsMips ) ) {

				generateMipmap( glTextureType );

			}

			state.unbindTexture();

		}

		// Setup depth and stencil buffers

		if ( renderTarget.depthBuffer ) {

			setupDepthRenderbuffer( renderTarget );

		}

	}

	function updateRenderTargetMipmap( renderTarget ) {

		const supportsMips = isPowerOfTwo( renderTarget ) || isWebGL2;

		const textures = renderTarget.isWebGLMultipleRenderTargets === true ? renderTarget.texture : [ renderTarget.texture ];

		for ( let i = 0, il = textures.length; i < il; i ++ ) {

			const texture = textures[ i ];

			if ( textureNeedsGenerateMipmaps( texture, supportsMips ) ) {

				const target = renderTarget.isWebGLCubeRenderTarget ? _gl.TEXTURE_CUBE_MAP : _gl.TEXTURE_2D;
				const webglTexture = properties.get( texture ).__webglTexture;

				state.bindTexture( target, webglTexture );
				generateMipmap( target );
				state.unbindTexture();

			}

		}

	}

	function updateMultisampleRenderTarget( renderTarget ) {

		if ( ( isWebGL2 && renderTarget.samples > 0 ) && useMultisampledRTT( renderTarget ) === false ) {

			const textures = renderTarget.isWebGLMultipleRenderTargets ? renderTarget.texture : [ renderTarget.texture ];
			const width = renderTarget.width;
			const height = renderTarget.height;
			let mask = _gl.COLOR_BUFFER_BIT;
			const invalidationArray = [];
			const depthStyle = renderTarget.stencilBuffer ? _gl.DEPTH_STENCIL_ATTACHMENT : _gl.DEPTH_ATTACHMENT;
			const renderTargetProperties = properties.get( renderTarget );
			const isMultipleRenderTargets = ( renderTarget.isWebGLMultipleRenderTargets === true );

			// If MRT we need to remove FBO attachments
			if ( isMultipleRenderTargets ) {

				for ( let i = 0; i < textures.length; i ++ ) {

					state.bindFramebuffer( _gl.FRAMEBUFFER, renderTargetProperties.__webglMultisampledFramebuffer );
					_gl.framebufferRenderbuffer( _gl.FRAMEBUFFER, _gl.COLOR_ATTACHMENT0 + i, _gl.RENDERBUFFER, null );

					state.bindFramebuffer( _gl.FRAMEBUFFER, renderTargetProperties.__webglFramebuffer );
					_gl.framebufferTexture2D( _gl.DRAW_FRAMEBUFFER, _gl.COLOR_ATTACHMENT0 + i, _gl.TEXTURE_2D, null, 0 );

				}

			}

			state.bindFramebuffer( _gl.READ_FRAMEBUFFER, renderTargetProperties.__webglMultisampledFramebuffer );
			state.bindFramebuffer( _gl.DRAW_FRAMEBUFFER, renderTargetProperties.__webglFramebuffer );

			for ( let i = 0; i < textures.length; i ++ ) {

				invalidationArray.push( _gl.COLOR_ATTACHMENT0 + i );

				if ( renderTarget.depthBuffer ) {

					invalidationArray.push( depthStyle );

				}

				const ignoreDepthValues = ( renderTargetProperties.__ignoreDepthValues !== undefined ) ? renderTargetProperties.__ignoreDepthValues : false;

				if ( ignoreDepthValues === false ) {

					if ( renderTarget.depthBuffer ) mask |= _gl.DEPTH_BUFFER_BIT;
					if ( renderTarget.stencilBuffer ) mask |= _gl.STENCIL_BUFFER_BIT;

				}

				if ( isMultipleRenderTargets ) {

					_gl.framebufferRenderbuffer( _gl.READ_FRAMEBUFFER, _gl.COLOR_ATTACHMENT0, _gl.RENDERBUFFER, renderTargetProperties.__webglColorRenderbuffer[ i ] );

				}

				if ( ignoreDepthValues === true ) {

					_gl.invalidateFramebuffer( _gl.READ_FRAMEBUFFER, [ depthStyle ] );
					_gl.invalidateFramebuffer( _gl.DRAW_FRAMEBUFFER, [ depthStyle ] );

				}

				if ( isMultipleRenderTargets ) {

					const webglTexture = properties.get( textures[ i ] ).__webglTexture;
					_gl.framebufferTexture2D( _gl.DRAW_FRAMEBUFFER, _gl.COLOR_ATTACHMENT0, _gl.TEXTURE_2D, webglTexture, 0 );

				}

				_gl.blitFramebuffer( 0, 0, width, height, 0, 0, width, height, mask, _gl.NEAREST );

				if ( supportsInvalidateFramebuffer ) {

					_gl.invalidateFramebuffer( _gl.READ_FRAMEBUFFER, invalidationArray );

				}


			}

			state.bindFramebuffer( _gl.READ_FRAMEBUFFER, null );
			state.bindFramebuffer( _gl.DRAW_FRAMEBUFFER, null );

			// If MRT since pre-blit we removed the FBO we need to reconstruct the attachments
			if ( isMultipleRenderTargets ) {

				for ( let i = 0; i < textures.length; i ++ ) {

					state.bindFramebuffer( _gl.FRAMEBUFFER, renderTargetProperties.__webglMultisampledFramebuffer );
					_gl.framebufferRenderbuffer( _gl.FRAMEBUFFER, _gl.COLOR_ATTACHMENT0 + i, _gl.RENDERBUFFER, renderTargetProperties.__webglColorRenderbuffer[ i ] );

					const webglTexture = properties.get( textures[ i ] ).__webglTexture;

					state.bindFramebuffer( _gl.FRAMEBUFFER, renderTargetProperties.__webglFramebuffer );
					_gl.framebufferTexture2D( _gl.DRAW_FRAMEBUFFER, _gl.COLOR_ATTACHMENT0 + i, _gl.TEXTURE_2D, webglTexture, 0 );

				}

			}

			state.bindFramebuffer( _gl.DRAW_FRAMEBUFFER, renderTargetProperties.__webglMultisampledFramebuffer );

		}

	}

	function getRenderTargetSamples( renderTarget ) {

		return Math.min( capabilities.maxSamples, renderTarget.samples );

	}

	function useMultisampledRTT( renderTarget ) {

		const renderTargetProperties = properties.get( renderTarget );

		return isWebGL2 && renderTarget.samples > 0 && extensions.has( 'WEBGL_multisampled_render_to_texture' ) === true && renderTargetProperties.__useRenderToTexture !== false;

	}

	function updateVideoTexture( texture ) {

		const frame = info.render.frame;

		// Check the last frame we updated the VideoTexture

		if ( _videoTextures.get( texture ) !== frame ) {

			_videoTextures.set( texture, frame );
			texture.update();

		}

	}

	function verifyColorSpace( texture, image ) {

		const colorSpace = texture.colorSpace;
		const format = texture.format;
		const type = texture.type;

		if ( texture.isCompressedTexture === true || texture.isVideoTexture === true || texture.format === _SRGBAFormat ) return image;

		if ( colorSpace !== LinearSRGBColorSpace && colorSpace !== NoColorSpace ) {

			// sRGB

			if ( ColorManagement.getTransfer( colorSpace ) === SRGBTransfer ) {

				if ( isWebGL2 === false ) {

					// in WebGL 1, try to use EXT_sRGB extension and unsized formats

					if ( extensions.has( 'EXT_sRGB' ) === true && format === RGBAFormat ) {

						texture.format = _SRGBAFormat;

						// it's not possible to generate mips in WebGL 1 with this extension

						texture.minFilter = LinearFilter;
						texture.generateMipmaps = false;

					} else {

						// slow fallback (CPU decode)

						image = ImageUtils.sRGBToLinear( image );

					}

				} else {

					// in WebGL 2 uncompressed textures can only be sRGB encoded if they have the RGBA8 format

					if ( format !== RGBAFormat || type !== UnsignedByteType ) {

						console.warn( 'THREE.WebGLTextures: sRGB encoded textures have to use RGBAFormat and UnsignedByteType.' );

					}

				}

			} else {

				console.error( 'THREE.WebGLTextures: Unsupported texture color space:', colorSpace );

			}

		}

		return image;

	}

	//

	this.allocateTextureUnit = allocateTextureUnit;
	this.resetTextureUnits = resetTextureUnits;

	this.setTexture2D = setTexture2D;
	this.setTexture2DArray = setTexture2DArray;
	this.setTexture3D = setTexture3D;
	this.setTextureCube = setTextureCube;
	this.rebindTextures = rebindTextures;
	this.setupRenderTarget = setupRenderTarget;
	this.updateRenderTargetMipmap = updateRenderTargetMipmap;
	this.updateMultisampleRenderTarget = updateMultisampleRenderTarget;
	this.setupDepthRenderbuffer = setupDepthRenderbuffer;
	this.setupFrameBufferTexture = setupFrameBufferTexture;
	this.useMultisampledRTT = useMultisampledRTT;

}

export { WebGLTextures };
