render.SetViewPort
Example
Renders a screen with a dimension of 32 X 32 and resets the render system to normal.
local oldW, oldH = ScrW(), ScrH()
local oldRT = render.GetRenderTarget()
render.SetRenderTarget(RTName)
render.Clear(0,0,0,255)
render.SetViewPort(0,0,32,32)
render.RenderView(CamData)
render.SetRenderTarget(oldRT)
render.SetViewPort(0,0,oldW,oldH)