Values
Disabled
Do not use a debug mode.
Wireframe
Draw all objects as wireframe models.
Overdraw
Draw all objects in a way that displays how much overdraw is occurring. Overdraw occurs when a section of pixels is drawn and shaded and then another object covers it up. To optimize a scene, you should reduce overdraw.
Shadeless
Draw all objects without shading. Equivalent to setting all objects shaders to unshaded.