FAQ/Depth Buffer

Enabling depth buffering

In order to use depth buffering, the following must occur:.

• The current framebuffer, whether an FBO or the default framebuffer, must have a depth buffer.
• Depth testing must be enabled. This is done by calling glEnable(GL_DEPTH_TEST).
• The depth range zNear and zFar must be set properly. Use glDepthRange to set these values.
• The depth buffer must be cleared when appropriate. This can be done by using glClear with the GL_DEPTH_BUFFER_BIT (along with glClearDepth to set the value that it will be cleared to). glClearBuffer can also be used to clear specific buffers.

Depth buffer precision

Main article: Depth Buffer Precision

Depth Buffer and Perspective Rendering

Depth buffering doesn't work in my perspective rendering. What's going on?

Write Image To Depth Buffer

How do I write a previously stored depth image to the depth buffer?

How do I turn off the zNear clipping plane?

See this question in the Clipping section.

An article about depth buffer precision http://www.sjbaker.org/steve/omniv/love_your_z_buffer.html