The clear mode when the sub-viewport is used as a render target. The update mode when the sub-viewport is used as a render target. The width and height of the sub-viewport. The 2D size override of the sub-viewport. If either the width or height is [code]0[/code], the override is disabled. If [code]true[/code], the 2D size override affects stretch as well. If [code]true[/code], the sub-viewport will be used in AR/VR process. Always clear the render target before drawing. Never clear the render target. Clear the render target next frame, then switch to [constant CLEAR_MODE_NEVER]. Do not update the render target. Update the render target once, then switch to [constant UPDATE_DISABLED]. Update the render target only when it is visible. This is the default value. Update the render target only when the its parent is visible. Always update the render target.