Force linear encoding for WebXR render targets (#24698)

* force linear encoding for WebXR render targets

* remove isWebXRRenderTarget

src/renderers/webgl/WebGLTextures.js

@@ -135,7 +135,7 @@ function WebGLTextures( _gl, extensions, state, properties, capabilities, utils,
 
 	}
 
-	function getInternalFormat( internalFormatName, glFormat, glType, encoding, isVideoTexture = false ) {
+	function getInternalFormat( internalFormatName, glFormat, glType, encoding, forceLinearEncoding = false ) {
 
 		if ( isWebGL2 === false ) return glFormat;
 
@@ -169,7 +169,7 @@ function WebGLTextures( _gl, extensions, state, properties, capabilities, utils,
 
 			if ( glType === _gl.FLOAT ) internalFormat = _gl.RGBA32F;
 			if ( glType === _gl.HALF_FLOAT ) internalFormat = _gl.RGBA16F;
-			if ( glType === _gl.UNSIGNED_BYTE ) internalFormat = ( encoding === sRGBEncoding && isVideoTexture === false ) ? _gl.SRGB8_ALPHA8 : _gl.RGBA8;
+			if ( glType === _gl.UNSIGNED_BYTE ) internalFormat = ( encoding === sRGBEncoding && forceLinearEncoding === false ) ? _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;
 
@@ -1593,7 +1593,7 @@ function WebGLTextures( _gl, extensions, state, properties, capabilities, utils,
 
 					const glFormat = utils.convert( texture.format, texture.encoding );
 					const glType = utils.convert( texture.type );
-					const glInternalFormat = getInternalFormat( texture.internalFormat, glFormat, glType, texture.encoding );
+					const glInternalFormat = getInternalFormat( texture.internalFormat, glFormat, glType, texture.encoding, renderTarget.isXRRenderTarget );
 					const samples = getRenderTargetSamples( renderTarget );
 					_gl.renderbufferStorageMultisample( _gl.RENDERBUFFER, samples, glInternalFormat, renderTarget.width, renderTarget.height );