- Current Shader: Current shader name used by the mesh in the viewport.
- 3D Mesh: 3D mesh on which you can paint on.
- Background: Display the environment map used by the viewport to light your 3D Mesh.
- Axis: Indicate the current direction of the world based on the camera rotation.
It is possible to quickly cycle through the channels of the current texture set by pressing the "C" shortcut.
This will switch the viewport into the "solo" mode, where the channel is displayed without any lighting information. It is possible to go back in the "Material" mode by pressing "M".
The viewer settings in display settings window allows to control some parameters related the 3D view.
The shader settings is also where you can change the shader used by a Substance Painter project.
See the shader settings page for more details.