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65 lines
2.4 KiB
Markdown
65 lines
2.4 KiB
Markdown
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**_glClear:** clear buffers to preset values
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## Syntax
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> : [SUB](SUB) _glClear ([BYVAL](BYVAL) mask AS [_UNSIGNED](_UNSIGNED) [LONG](LONG))
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> : void **_glClear**(GLbitfield mask);
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## Parameters
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* *mask* that indicate the buffer [OR](OR) buffers to be cleared. The three masks are [_GL_COLOR_BUFFER_BIT](_GL_COLOR_BUFFER_BIT), [_GL_DEPTH_BUFFER_BIT](_GL_DEPTH_BUFFER_BIT), and [_GL_STENCIL_BUFFER_BIT](_GL_STENCIL_BUFFER_BIT).
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## Description
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* [_glClear](_glClear) sets the bitplane area of the window to values previously selected by [_glClearColor](_glClearColor), [glClearDepth](glClearDepth), and [_glClearStencil](_glClearStencil).
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* Multiple color buffers can be cleared simultaneously by selecting more than one buffer at a time using [_glDrawBuffer](_glDrawBuffer).
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* The pixel ownership test, the scissor test, dithering, and the buffer writemasks affect the operation of [_glClear](_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).
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* [_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:
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> :: [_GL_COLOR_BUFFER_BIT](_GL_COLOR_BUFFER_BIT): Indicates the buffers currently enabled for color writing.
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> :: [_GL_DEPTH_BUFFER_BIT](_GL_DEPTH_BUFFER_BIT): Indicates the depth buffer.
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> :: [_GL_STENCIL_BUFFER_BIT](_GL_STENCIL_BUFFER_BIT): Indicates the stencil buffer.
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* The value to which each buffer is cleared depends on the setting of the clear value for that buffer.
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## Notes
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If a buffer is not present, then a **_glClear** directed at that buffer has no effect.
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## Error(s)
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[_GL_INVALID_VALUE](_GL_INVALID_VALUE) is generated if any bit other than the three defined bits is set in mask.
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## Use With
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[_glGet](_glGet) with argument [_GL_DEPTH_CLEAR_VALUE](_GL_DEPTH_CLEAR_VALUE)
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[_glGet](_glGet) with argument [_GL_COLOR_CLEAR_VALUE](_GL_COLOR_CLEAR_VALUE)
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[_glGet](_glGet) with argument [_GL_STENCIL_CLEAR_VALUE](_GL_STENCIL_CLEAR_VALUE)
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## See Also
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* [_GL](_GL)
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* [_glClearBuffer](_glClearBuffer), [_glClearColor](_glClearColor), [_glClearDepth](_glClearDepth), [_glClearStencil](_glClearStencil)
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* [_glColorMask](_glColorMask), [_glDepthMask](_glDepthMask), [_glStencilMask](_glStencilMask)
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* [_glDrawBuffer](_glDrawBuffer), [_glDrawBuffers](_glDrawBuffers)
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* [_glScissor](_glScissor)
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