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56 lines
2 KiB
Text
56 lines
2 KiB
Text
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'''_glClear:''' clear buffers to preset values
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{{PageSyntax}}
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:: [[SUB]] _glClear ([[BYVAL]] mask AS [[_UNSIGNED]] [[LONG]])
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:: void '''_glClear'''(GLbitfield {{Parameter|mask}});
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{{Parameters}}
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* ''mask'' that indicate the buffer [[OR]] buffers to be cleared. The three masks are [[_GL_COLOR_BUFFER_BIT]], [[_GL_DEPTH_BUFFER_BIT]], and [[_GL_STENCIL_BUFFER_BIT]].
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{{PageDescription}}
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* [[_glClear]] sets the bitplane area of the window to values previously selected by [[_glClearColor]], [[glClearDepth]], and [[_glClearStencil]].
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* Multiple color buffers can be cleared simultaneously by selecting more than one buffer at a time using [[_glDrawBuffer]].
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* 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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* [[_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]]: Indicates the buffers currently enabled for color writing.
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::: [[_GL_DEPTH_BUFFER_BIT]]: Indicates the depth buffer.
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::: [[_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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{{PageNotes}}
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If a buffer is not present, then a '''_glClear''' directed at that buffer has no effect.
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{{PageErrors}}
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{{KW|_GL_INVALID_VALUE}} is generated if any bit other than the three defined bits is set in {{Parameter|mask}}.
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{{PageUseWith}}
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{{KW|_glGet}} with argument {{KW|_GL_DEPTH_CLEAR_VALUE}}
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{{KW|_glGet}} with argument {{KW|_GL_COLOR_CLEAR_VALUE}}
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{{KW|_glGet}} with argument {{KW|_GL_STENCIL_CLEAR_VALUE}}
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{{PageSeeAlso}}
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* [[_GL]]
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* [[_glClearBuffer]], [[_glClearColor]], [[_glClearDepth]], [[_glClearStencil]]
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* [[_glColorMask]], [[_glDepthMask]], [[_glStencilMask]]
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* [[_glDrawBuffer]], [[_glDrawBuffers]]
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* [[_glScissor]]
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{{PageCopyright}}
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