fix

build/three.js

@@ -15733,7 +15733,7 @@
 				_gl.framebufferRenderbuffer(_gl.FRAMEBUFFER, _gl.DEPTH_STENCIL_ATTACHMENT, _gl.RENDERBUFFER, renderbuffer);
 			} else {
 				// Use the first texture for MRT so far
-				const texture = renderTarget.isWebGLMultipleRenderTargets === true ? renderTarget.texture[0] : renderTarget.texture;
+				const texture = renderTarget.textures[0];
 				const glFormat = utils.convert(texture.format);
 				const glType = utils.convert(texture.type);
 				const glInternalFormat = getInternalFormat(texture.internalFormat, glFormat, glType);

src/renderers/WebGLCubeRenderTarget.js

@@ -128,9 +128,9 @@ class WebGLCubeRenderTarget extends WebGLRenderTarget {
 
 		const currentRenderTarget = renderer.getRenderTarget();
 
-		for ( let f = 0; f < 6; f ++ ) {
+		for ( let i = 0; i < 6; i ++ ) {
 
-			renderer.setRenderTarget( this, f );
+			renderer.setRenderTarget( this, i );
 
 			renderer.clear( color, depth, stencil );
 

src/textures/CubeTexture.js

@@ -19,7 +19,7 @@ class CubeTexture extends Texture {
 
 		// three.js uses a right-handed coordinate system. So environment maps used in three.js appear to have px and nx swapped
 		// and the flag _needsFlipEnvMap controls this conversion. The flip is not required (and thus _needsFlipEnvMap is set to false)
-		// when using a cube texture in WebGLCubeRenderTarget.textures.
+		// when using WebGLCubeRenderTarget.texture as a cube texture.
 
 		this._needsFlipEnvMap = true;