Ambient Occlusion

Edits In Progress

Valve's Source engine uses SSAO which stands for Screen Space Ambient Occlusion.

What Visual Difference Ambient Occlusion Makes

Ambient Occlusion in the Source engine determines the diffusion of soft shadows

Enabling Ambient Occlusion

Enabling Ambient Occlusion is as easy as right-clicking the viewport and heading to your render settings. In the dialog box for your render settings, check the box adjacent from the Ambient Occlusion setting which reads "enable". Make sure that the drop-down menu next to the AO setting reads "AO Only" and not "Outline(link) Only" or "AO & Outline" (edit for proof, add pictures).

Note:If there's ugly black speckles frequenting the scene upon enabling AO, that is usually normal. All this means is that you are not looking through your scene camera with at least 32 samples of depth of field rendered in the viewport (you must be in the Clip Editor).

-Comparison picture: No DoF versus DoF at varying sample rates

Camera Settings

-SSAO Bias -SSAO Strength -SSAO Radius