copy method
Implementation
WebGLRenderTarget copy(WebGLRenderTarget source) {
width = source.width;
height = source.height;
depth = source.depth;
viewport.copy(source.viewport);
scissor.copy(source.scissor);
texture = source.texture.clone();
texture.isRenderTargetTexture = true;
texture.source = Source(source.texture.image);
depthBuffer = source.depthBuffer;
stencilBuffer = source.stencilBuffer;
if (source.depthTexture != null) {
depthTexture = source.depthTexture!.clone();
}
samples = source.samples;
return this;
}