mirror of
https://github.com/QB64-Phoenix-Edition/QB64pe.git
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6e01fc8dce
Added new _STRCMP and _STRICMP commands for quick string comparisons. Cleaned up QB64 to finish removing the QUI (quick user insert) code and folders. Altered UCASE and LCASE routines to be faster in some situations for us.
56 lines
2 KiB
Plaintext
56 lines
2 KiB
Plaintext
'''_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}} |