An offset into the list of viewports.
- iOS 13.0+
- macOS 10.15.4+
- Mac Catalyst 13.4+
To specify a list of offsets, call the
When your app renders to different render targets, you specify the render target index to render to in your vertex shader by adding the
viewport attribute to one of the vertex shader's outputs. If you are using vertex amplification, Metal calculates the index for each amplified vertex by adding the index offset for the vertex to the value returned from your shader.