Uniform uses a system called Surface Views to configure how the viewport should render objects. This is used to set if you want to see just volumes, colors, full PBR shading, flat textures, etc. Surface views can be of different types and create different kinds of interactive visual effects. By default, Uniform uses a Chart Surface View.

For interacting with the Char Surface View, hold down the surface view shortcuts to activate the tool, then drag on a viewport. You see that a square appears. Dragging on this square, left and right will blend between the shapes and color visualization. Dragging up and down will change the PBR energy contribution.

If you drag to the bottom left corner, Uniform will render the viewport with a high contrast static light, as you drag to the right, you see that contrast starts decreasing and the painted colors appear. Once you reach the right corner, there is no longer any shape and volume information left, but only colors with flat shading.

If you drag to the upper left corner of the chart, Uniform will render the PBR materials with full energy contribution, but without any color information. You can use this to check the lighting of your scene. Finally, the upper right corner of the chart will render the viewport with full PBR contribution and colors, as it will look in a final render.

You can use the chart to make any non photorealistic blending between all these shading modes so you can get the most comfortable viewport rendering depending on the task you want to focus on.