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 depth test element is a numeric parameter of an active object defining the precondition for rendering a point. The depth (distance) of the point is compared with the depth of the point being overwritten. The point will be drawn only if the test precondition is met.

 

1 never (pixel will never be drawn)

2 < (distance must be less)

3 = (distance must be equal)

4 <= (distance must be less or equal; default)

5 > (distance must be greater)

6 <> (distance must not be equal)

7 >= (distance must be greater or equal)

8 always (pixel will always be drawn)

 

The default value is 4; the point will be drawn if its distance from the camera is smaller or identical. After setting the depth test to 8 and switching the write depth information switch off the function of the depth buffer will be switched off. The rendering speed can be thus raised slightly, especially when using a software driver.