KTX2Loader: Remove `RGB_S3TC_DXT1_Format` usage. (#28069)

examples/jsm/loaders/KTX2Loader.js

@@ -31,13 +31,13 @@ import {
 	RGB_ETC1_Format,
 	RGB_ETC2_Format,
 	RGB_PVRTC_4BPPV1_Format,
-	RGB_S3TC_DXT1_Format,
 	RGBA_ASTC_4x4_Format,
 	RGBA_ASTC_6x6_Format,
 	RGBA_BPTC_Format,
 	RGBA_ETC2_EAC_Format,
 	RGBA_PVRTC_4BPPV1_Format,
 	RGBA_S3TC_DXT5_Format,
+	RGBA_S3TC_DXT1_Format,
 	RGBAFormat,
 	RGFormat,
 	SRGBColorSpace,
@@ -384,7 +384,7 @@ KTX2Loader.EngineFormat = {
 	RGB_ETC1_Format: RGB_ETC1_Format,
 	RGB_ETC2_Format: RGB_ETC2_Format,
 	RGB_PVRTC_4BPPV1_Format: RGB_PVRTC_4BPPV1_Format,
-	RGB_S3TC_DXT1_Format: RGB_S3TC_DXT1_Format,
+	RGBA_S3TC_DXT1_Format: RGBA_S3TC_DXT1_Format,
 };
 
 
@@ -600,7 +600,7 @@ KTX2Loader.BasisWorker = function () {
 			if: 'dxtSupported',
 			basisFormat: [ BasisFormat.ETC1S, BasisFormat.UASTC_4x4 ],
 			transcoderFormat: [ TranscoderFormat.BC1, TranscoderFormat.BC3 ],
-			engineFormat: [ EngineFormat.RGB_S3TC_DXT1_Format, EngineFormat.RGBA_S3TC_DXT5_Format ],
+			engineFormat: [ EngineFormat.RGBA_S3TC_DXT1_Format, EngineFormat.RGBA_S3TC_DXT5_Format ],
 			priorityETC1S: 4,
 			priorityUASTC: 5,
 			needsPowerOfTwo: false,