Merge pull request #18681 from frankolivier/dev

WebGLRenderer: Add mipmap & compressed texture handling to .copyTextureToTexture().

src/renderers/WebGLRenderer.js

@@ -2768,6 +2768,8 @@ function WebGLRenderer( parameters ) {
 
 	this.copyTextureToTexture = function ( position, srcTexture, dstTexture, level ) {
 
+		if ( level === undefined ) level = 0;
+
 		var width = srcTexture.image.width;
 		var height = srcTexture.image.height;
 		var glFormat = utils.convert( dstTexture.format );
@@ -2777,14 +2779,25 @@ function WebGLRenderer( parameters ) {
 
 		if ( srcTexture.isDataTexture ) {
 
-			_gl.texSubImage2D( _gl.TEXTURE_2D, level || 0, position.x, position.y, width, height, glFormat, glType, srcTexture.image.data );
+			_gl.texSubImage2D( _gl.TEXTURE_2D, level, position.x, position.y, width, height, glFormat, glType, srcTexture.image.data );
 
 		} else {
 
-			_gl.texSubImage2D( _gl.TEXTURE_2D, level || 0, position.x, position.y, glFormat, glType, srcTexture.image );
+			if ( srcTexture.isCompressedTexture ) {
+
+				_gl.compressedTexSubImage2D( _gl.TEXTURE_2D, level, position.x, position.y, srcTexture.mipmaps[ 0 ].width, srcTexture.mipmaps[ 0 ].height, glFormat, srcTexture.mipmaps[ 0 ].data );
+
+			} else {
+
+				_gl.texSubImage2D( _gl.TEXTURE_2D, level, position.x, position.y, glFormat, glType, srcTexture.image );
+
+			}
 
 		}
 
+		// Generate mipmaps only when copying level 0
+		if ( level === 0 && dstTexture.generateMipmaps ) _gl.generateMipmap( _gl.TEXTURE_2D );
+
 		state.unbindTexture();
 
 	};