GLAPI/glClear: Difference between revisions
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== Function Definition == | == Function Definition == | ||
void '''glClear'''(GLbitfield | void '''glClear'''(GLbitfield {{param|mask}}); | ||
; mask | ; mask | ||
: Bitwise OR of masks that indicate the buffers to be cleared. The three masks are {{ | : Bitwise OR of masks that indicate the buffers to be cleared. The three masks are {{enum|GL_COLOR_BUFFER_BIT}}, {{enum|GL_DEPTH_BUFFER_BIT}}, and {{enum|GL_STENCIL_BUFFER_BIT}}. | ||
== Description == | == Description == | ||
'''glClear''' sets the bitplane area of the window to values previously selected by | '''glClear''' sets the bitplane area of the window to values previously selected by {{apifunc|glClearColor}}, {{apifunc|glClearDepth}}, and {{apifunc|glClearStencil}}. Multiple color buffers can be cleared simultaneously by selecting more than one buffer at a time using {{apifunc|glDrawBuffers}}. | ||
The pixel ownership test, the scissor test, dithering, and the buffer writemasks affect the operation of '''glClear'''. The scissor box bounds the cleared region. Alpha function, blend function, logical operation, stenciling, texture mapping, and depth-buffering are ignored by '''glClear'''. | The pixel ownership test, the scissor test, dithering, and the buffer writemasks affect the operation of '''glClear'''. The scissor box bounds the cleared region. Alpha function, blend function, logical operation, stenciling, texture mapping, and depth-buffering are ignored by '''glClear'''. | ||
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The values are as follows: | The values are as follows: | ||
; {{ | ; {{enum|GL_COLOR_BUFFER_BIT}} | ||
: Indicates the buffers currently enabled for color writing. | : Indicates the buffers currently enabled for color writing. | ||
; {{ | ; {{enum|GL_DEPTH_BUFFER_BIT}} | ||
: Indicates the depth buffer. | : Indicates the depth buffer. | ||
; {{ | ; {{enum|GL_STENCIL_BUFFER_BIT}} | ||
: Indicates the stencil buffer. | : Indicates the stencil buffer. | ||
The value to which each buffer is cleared depends on the setting of the clear value for that buffer. | The value to which each buffer is cleared depends on the setting of the clear value for that buffer. | ||
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== Errors == | == Errors == | ||
{{ | {{enum|GL_INVALID_VALUE}} is generated if any bit other than the three defined bits is set in {{param|mask}}. | ||
== Associated Gets == | == Associated Gets == | ||
{{apifunc|glGet}} with argument {{enum|GL_DEPTH_CLEAR_VALUE}} | |||
{{apifunc|glGet}} with argument {{enum|GL_COLOR_CLEAR_VALUE}} | |||
{{apifunc|glGet}} with argument {{enum|GL_STENCIL_CLEAR_VALUE}} | |||
== See Also == | == See Also == | ||
{{apifunc|glClearBuffer}}, {{apifunc|glClearColor}}, {{apifunc|glClearDepth}}, {{apifunc|glClearStencil}}, {{apifunc|glColorMask}}, {{apifunc|glDepthMask}}, {{apifunc|glDrawBuffer}}, {{apifunc|glDrawBuffers}}, {{apifunc|glScissor}}, {{apifunc|glStencilMask}} | |||
== Copyright == | == Copyright == | ||
Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see [ | Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see [https://khronos.org/registry/OpenGL-Refpages/LICENSES/LicenseRef-FreeB.txt LicenseRef-FreeB]. | ||
[[Category:Core API Ref Whole Framebuffer|ClearStencil]] | |||
[[Category:Core API Reference|Clear]] | [[Category:Core API Reference|Clear]] | ||
Latest revision as of 21:54, 5 February 2021
| Core in version | 4.6 | |
|---|---|---|
| Core since version | 1.0 | |
glClear: clear buffers to preset values
Function Definition
void glClear(GLbitfield mask);
- mask
- Bitwise OR of masks that indicate the buffers to be cleared. The three masks are GL_COLOR_BUFFER_BIT, GL_DEPTH_BUFFER_BIT, and GL_STENCIL_BUFFER_BIT.
Description
glClear sets the bitplane area of the window to values previously selected by glClearColor, glClearDepth, and glClearStencil. Multiple color buffers can be cleared simultaneously by selecting more than one buffer at a time using glDrawBuffers.
The pixel ownership test, the scissor test, dithering, and the buffer writemasks affect the operation of glClear. The scissor box bounds the cleared region. Alpha function, blend function, logical operation, stenciling, texture mapping, and depth-buffering are ignored by glClear.
glClear takes a single argument that is the bitwise OR of several values indicating which buffer is to be cleared.
The values are as follows:
- GL_COLOR_BUFFER_BIT
- Indicates the buffers currently enabled for color writing.
- GL_DEPTH_BUFFER_BIT
- Indicates the depth buffer.
- GL_STENCIL_BUFFER_BIT
- Indicates the stencil buffer.
The value to which each buffer is cleared depends on the setting of the clear value for that buffer.
Notes
If a buffer is not present, then a glClear directed at that buffer has no effect.
Errors
GL_INVALID_VALUE is generated if any bit other than the three defined bits is set in mask.
Associated Gets
glGet with argument GL_DEPTH_CLEAR_VALUE
glGet with argument GL_COLOR_CLEAR_VALUE
glGet with argument GL_STENCIL_CLEAR_VALUE
See Also
glClearBuffer, glClearColor, glClearDepth, glClearStencil, glColorMask, glDepthMask, glDrawBuffer, glDrawBuffers, glScissor, glStencilMask
Copyright
Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see LicenseRef-FreeB.