Updates the internal RenderTexture that a CustomRenderTexture uses for double buffering, so that it matches the size and format of the CustomRenderRexture.
Use this if you are implementing your own CustomRenderTexture update loop for a CustomRenderTexture that is double buffered. Unity does this automatically as part of the built-in CustomRenderTexture update loop.
See Also: Rendering.GraphicsSettings.disableBuiltinCustomRenderTextures, CustomRenderTexture.doubleBuffered
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