When rendering (drawing) objects each point being rendered is stored together with its depth information, i.e. with its distance from the camera. When rendering a further object each point being rendered is depth tested. A new point will be drawn only if it is situated nearer to the camera than the foregoing point.

 

The write depth information element is a logic switch defining whether the depth information of an active object's point will be stored. This switch being off may be utilized to reach special effects. If the depth test is switched off at the same time, the rendering speed can be raised slightly (especially when using a software driver).