These options are available under VRED Visualization > Advanced OpenGL Settings.
Wireframe: The wireframe button toggles wireframe rendering to On or Off. All currently selected objects are drawn in set render mode and a wireframe mode. The wireframe color can be set in: Edit » Preferences » Render Options » Wireframe.
Two-Sided Lighting: Enables/disables two-sided lighting. It allows toggling the illumination of polygon backsides globally.
Realtime shadow: Activates/deactivates real time shadows. Only available in OpenGL mode.
Ambient Occlusion Shadows: Activates Ambient Occlusion calculation.
Geometry Light Sources: Only active if Realtime Shadow is selected. Treats self-illuminated geometries as light source. Only in OpenGL render mode.
Backface Culling: Activates/deactivates backface culling. Backface culling renders only the faces with normals pointing toward the camera.
Occlusion Culling: Renders visible geometries only; the render engine excludes polygons/patches hidden by other objects on rendering.
Depth Only Pass: Renders the scene once using only the depth values. It can be used for optimization with complex shaders.