The antialiasing level for the RenderTexture.
Anti-aliasing value indicates the number of samples per pixel. The value can be 1, 2, 4 or 8. 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.