FAQ/Depth Buffer: Difference between revisions

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m (Alfonse moved page Depth Buffer to FAQ/Depth Buffer without leaving a redirect: This is more of a FAQ-style page; the current page needs to become a redirect to real info.)
 
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; [[Enable Depth Buffering]] : How do I make depth buffering work?
{{cleanup}}
 
== Enabling depth buffering ==
 
In order to use depth buffering, the following must occur:.
 
* The current framebuffer, whether an [[Framebuffer Object|FBO]] or the [[Default Framebuffer|default framebuffer]], must have a depth buffer.
* Depth testing must be enabled. This is done by calling {{code|glEnable(GL_DEPTH_TEST)}}. By default, depth testing is disabled when you create the GL context.
* The depth function should be set with {{code|glDepthFunc}}. We recommend glDepthFunc(GL_LEQUAL) where LEQUAL means less or equal.
* The depth mask is set with {{code|glDepthMask}}. By default, this is GL_TRUE which means writing to the depth buffer is enabled. Use it as you see fit but don't forget that if you set it to GL_FALSE, glClear(GL_DEPTH_BUFFER_BIT) won't have any effect.
* The depth remap is set with {{code|glDepthRange}}. By default, this is glDepthRange(0.0, 1.0) and you don't need to touch it.
* 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). Typically, people use glClearDepth(1.0) to have the maximum. glClearBuffer can also be used to clear specific buffers (requires GL 3.0).
 
== Depth buffer precision ==
{{main|Depth Buffer Precision}}
 
; [[Depth Buffer and Perspective Rendering]] : Depth buffering doesn't work in my perspective rendering. What's going on?
; [[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?
; Write Image To Depth Buffer : How do I write a previously stored depth image to the depth buffer?
; [[Depth Buffer Precision]] : Depth buffering seems to work, but polygons seem to bleed through polygons that are in front of them. What's going on?
: Why is my depth buffer precision so poor?
: Why is there more precision at the front of the depth buffer?
: There is no way that a standard-sized depth buffer will have enough precision for my astronomically large scene. What are my options?
; How do I turn off the zNear clipping plane? : See [http://www.opengl.org/resources/faq/technical/clipping.htm#0050 this question] in the Clipping section.
; How do I turn off the zNear clipping plane? : See [http://www.opengl.org/resources/faq/technical/clipping.htm#0050 this question] in the Clipping section.
; An article about depth buffer precision http://www.sjbaker.org/steve/omniv/love_your_z_buffer.html
; Common Mistakes http://www.opengl.org/wiki/Common_Mistakes#Depth_Buffer_Precision
{{stub}}


 
[[Category:Framebuffer]]
 
[[Category:Depth Buffering]]
[[Category:General OpenGL]]

Latest revision as of 19:40, 28 June 2015

This article needs proper formatting or improved descriptions. Further details can be found on the talk page.

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). By default, depth testing is disabled when you create the GL context.
  • The depth function should be set with glDepthFunc. We recommend glDepthFunc(GL_LEQUAL) where LEQUAL means less or equal.
  • The depth mask is set with glDepthMask. By default, this is GL_TRUE which means writing to the depth buffer is enabled. Use it as you see fit but don't forget that if you set it to GL_FALSE, glClear(GL_DEPTH_BUFFER_BIT) won't have any effect.
  • The depth remap is set with glDepthRange. By default, this is glDepthRange(0.0, 1.0) and you don't need to touch it.
  • 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). Typically, people use glClearDepth(1.0) to have the maximum. glClearBuffer can also be used to clear specific buffers (requires GL 3.0).

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
Common Mistakes http://www.opengl.org/wiki/Common_Mistakes#Depth_Buffer_Precision
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