The antialiasing level for the RenderTexture.
Anti-aliasing value indicates the number of samples per pixel. If unsupported by the hardware or rendering API, the greatest supported number of samples less than the indicated number is used.
When a RenderTexture is using anti-aliasing, then any rendering into it will happen into the multi-sampled
texture, which will be "resolved" into a regular texture when switching to another render target. To the rest
of the system only this "resolved" surface is visible.