WebGLRenderer: Use ETC2 for ETC1 textures. (#28021)

* WebGLRenderer: Use ETC2 for ETC1 textures.

* KTX2Loader: Remove ETC1 override.

examples/jsm/loaders/KTX2Loader.js

@@ -160,9 +160,6 @@ class KTX2Loader extends Loader {
 					|| renderer.extensions.has( 'WEBKIT_WEBGL_compressed_texture_pvrtc' )
 			};
 
-			// https://github.com/mrdoob/three.js/pull/22928
-			this.workerConfig.etc1Supported = false;
-
 		}
 
 		return this;

examples/jsm/renderers/webgl/utils/WebGLUtils.js

@@ -114,33 +114,15 @@ class WebGLUtils {
 
 		}
 
-		// ETC1
+		// ETC
 
-		if ( p === RGB_ETC1_Format ) {
-
-			extension = extensions.get( 'WEBGL_compressed_texture_etc1' );
-
-			if ( extension !== null ) {
-
-				return extension.COMPRESSED_RGB_ETC1_WEBGL;
-
-			} else {
-
-				return null;
-
-			}
-
-		}
-
-		// ETC2
-
-		if ( p === RGB_ETC2_Format || p === RGBA_ETC2_EAC_Format ) {
+		if ( p === RGB_ETC1_Format || p === RGB_ETC2_Format || p === RGBA_ETC2_EAC_Format ) {
 
 			extension = extensions.get( 'WEBGL_compressed_texture_etc' );
 
 			if ( extension !== null ) {
 
-				if ( p === RGB_ETC2_Format ) return ( colorSpace === SRGBColorSpace ) ? extension.COMPRESSED_SRGB8_ETC2 : extension.COMPRESSED_RGB8_ETC2;
+				if ( p === RGB_ETC1_Format || p === RGB_ETC2_Format ) return ( colorSpace === SRGBColorSpace ) ? extension.COMPRESSED_SRGB8_ETC2 : extension.COMPRESSED_RGB8_ETC2;
 				if ( p === RGBA_ETC2_EAC_Format ) return ( colorSpace === SRGBColorSpace ) ? extension.COMPRESSED_SRGB8_ALPHA8_ETC2_EAC : extension.COMPRESSED_RGBA8_ETC2_EAC;
 
 			} else {

src/renderers/webgl/WebGLTextures.js

@@ -1,4 +1,4 @@
-import { LinearFilter, LinearMipmapLinearFilter, LinearMipmapNearestFilter, NearestFilter, NearestMipmapLinearFilter, NearestMipmapNearestFilter, RGBAFormat, RGB_ETC1_Format, DepthFormat, DepthStencilFormat, UnsignedIntType, UnsignedInt248Type, FloatType, MirroredRepeatWrapping, ClampToEdgeWrapping, RepeatWrapping, UnsignedByteType, NoColorSpace, LinearSRGBColorSpace, NeverCompare, AlwaysCompare, LessCompare, LessEqualCompare, EqualCompare, GreaterEqualCompare, GreaterCompare, NotEqualCompare, SRGBTransfer, LinearTransfer } from '../../constants.js';
+import { LinearFilter, LinearMipmapLinearFilter, LinearMipmapNearestFilter, NearestFilter, NearestMipmapLinearFilter, NearestMipmapNearestFilter, RGBAFormat, DepthFormat, DepthStencilFormat, UnsignedIntType, UnsignedInt248Type, FloatType, MirroredRepeatWrapping, ClampToEdgeWrapping, RepeatWrapping, UnsignedByteType, NoColorSpace, LinearSRGBColorSpace, NeverCompare, AlwaysCompare, LessCompare, LessEqualCompare, EqualCompare, GreaterEqualCompare, GreaterCompare, NotEqualCompare, SRGBTransfer, LinearTransfer } from '../../constants.js';
 import { createElementNS } from '../../utils.js';
 import { ColorManagement } from '../../math/ColorManagement.js';
 import { Vector2 } from '../../math/Vector2.js';
@@ -703,7 +703,7 @@ function WebGLTextures( _gl, extensions, state, properties, capabilities, utils,
 			let mipmap;
 			const mipmaps = texture.mipmaps;
 
-			const useTexStorage = ( texture.isVideoTexture !== true && glInternalFormat !== RGB_ETC1_Format );
+			const useTexStorage = ( texture.isVideoTexture !== true );
 			const allocateMemory = ( sourceProperties.__version === undefined ) || ( forceUpload === true );
 			const dataReady = source.dataReady;
 			const levels = getMipLevels( texture, image );

src/renderers/webgl/WebGLUtils.js

@@ -101,33 +101,15 @@ function WebGLUtils( gl, extensions ) {
 
 		}
 
-		// ETC1
+		// ETC
 
-		if ( p === RGB_ETC1_Format ) {
-
-			extension = extensions.get( 'WEBGL_compressed_texture_etc1' );
-
-			if ( extension !== null ) {
-
-				return extension.COMPRESSED_RGB_ETC1_WEBGL;
-
-			} else {
-
-				return null;
-
-			}
-
-		}
-
-		// ETC2
-
-		if ( p === RGB_ETC2_Format || p === RGBA_ETC2_EAC_Format ) {
+		if ( p === RGB_ETC1_Format || p === RGB_ETC2_Format || p === RGBA_ETC2_EAC_Format ) {
 
 			extension = extensions.get( 'WEBGL_compressed_texture_etc' );
 
 			if ( extension !== null ) {
 
-				if ( p === RGB_ETC2_Format ) return ( transfer === SRGBTransfer ) ? extension.COMPRESSED_SRGB8_ETC2 : extension.COMPRESSED_RGB8_ETC2;
+				if ( p === RGB_ETC1_Format || p === RGB_ETC2_Format ) return ( transfer === SRGBTransfer ) ? extension.COMPRESSED_SRGB8_ETC2 : extension.COMPRESSED_RGB8_ETC2;
 				if ( p === RGBA_ETC2_EAC_Format ) return ( transfer === SRGBTransfer ) ? extension.COMPRESSED_SRGB8_ALPHA8_ETC2_EAC : extension.COMPRESSED_RGBA8_ETC2_EAC;
 
 			} else {