Understand camera stacking
In the Universal Render Pipeline (URP), you use camera stacking to layer the output of multiple Cameras and create a single combined output. Camera stacking allows you to create effects such as a 3D model in a 2D UI, or the cockpit of a vehicle.
A camera stack consists of a Base Camera and one or more Overlay Cameras. A camera stack overrides the output of the Base Camera with the combined output of all the cameras in the camera stack. As a result, anything you can do with the output of a Base Camera, you can do with the output of a camera stack. For example, you can render a camera stack to a render target, or apply post-processing effects.
Refer to Set up a camera stack for more information. To download examples of camera stacking in URP, install the Camera Stacking samples.
Camera stacking and rendering order
URP performs several optimizations within a camera, including rendering order optimizations to reduce overdraw. However, when you use a camera stack, you define the order in which URP renders the cameras. You must be careful not to order the cameras in a way that causes excessive overdraw. For more information on overdraw in URP, refer to Rendering order optimizations.
Camera stacking and post-processing
You should only apply post-processing to the last camera in the stack, so the following applies:
- URP renders the post-processing effects only once, not repeatedly for each camera.
- The visual effects are consistent, because all the cameras in the stack receive the same post-processing.
Limitations
You cannot use a mix of different types of renderers (2D and 3D) for cameras in a camera stack.