|index||The render target index to use (from 0 to 3).|
|surface_id||The ID of the surface to use.|
This function is for use with the Shader Functions and sets the MRT (0 -
3) for native level shaders (DX9, DX11, OpenGL).
NOTE: When working with surfaces there is the possibility that they can cease to exist at any time due to them being stored in texture memory. You should ALWAYS check that a surface exists using surface_exists before referencing them directly. For further information see Surfaces.
The above code will set the render target 0 to the surface ID indexed in the variable "surf".