📄 fglclear.html
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<HTML><BODY><PRE> <STRONG>NAME</STRONG> <STRONG>fglClear</STRONG> - clear buffers to preset values <STRONG>FORTRAN</STRONG> <STRONG>SPECIFICATION</STRONG> SUBROUTINE <STRONG>fglClear</STRONG>( INTEGER*4 <EM>mask</EM> ) <STRONG>PARAMETERS</STRONG> <EM>mask</EM> Bitwise OR of masks that indicate the buffers to be cleared. The four masks are <STRONG>GL_COLOR_BUFFER_BIT</STRONG>, <STRONG>GL_DEPTH_BUFFER_BIT</STRONG>, <STRONG>GL_ACCUM_BUFFER_BIT</STRONG>, and <STRONG>GL_STENCIL_BUFFER_BIT</STRONG>. <STRONG>DESCRIPTION</STRONG> <STRONG>fglClear</STRONG> sets the bitplane area of the window to values previously selected by <STRONG>fglClearColor</STRONG>, <STRONG>fglClearIndex</STRONG>, <STRONG>fglClearDepth</STRONG>, <STRONG>fglClearStencil</STRONG>, and <STRONG>fglClearAccum</STRONG>. Multiple color buffers can be cleared simultaneously by selecting more than one buffer at a time using <STRONG>fglDrawBuffer</STRONG>. The pixel ownership test, the scissor test, dithering, and the buffer writemasks affect the operation of <STRONG>fglClear</STRONG>. The scissor box bounds the cleared region. Alpha function, blend function, logical operation, stenciling, texture mapping, and depth-buffering are ignored by <STRONG>fglClear</STRONG>. <STRONG>fglClear</STRONG> takes a single argument that is the bitwise OR of several values indicating which buffer is to be cleared. The values are as follows: <STRONG>GL_COLOR_BUFFER_BIT</STRONG> Indicates the buffers currently enabled for color writing. <STRONG>GL_DEPTH_BUFFER_BIT</STRONG> Indicates the depth buffer. <STRONG>GL_ACCUM_BUFFER_BIT</STRONG> Indicates the accumulation buffer. <STRONG>GL_STENCIL_BUFFER_BIT</STRONG> Indicates the stencil buffer. The value to which each buffer is cleared depends on the setting of the clear value for that buffer. <STRONG>NOTES</STRONG> If a buffer is not present, then a <STRONG>fglClear</STRONG> directed at that buffer has no effect. <STRONG>ERRORS</STRONG> <STRONG>GL_INVALID_VALUE</STRONG> is generated if any bit other than the four defined bits is set in <EM>mask</EM>. <STRONG>GL_INVALID_OPERATION</STRONG> is generated if <STRONG>fglClear</STRONG> is executed between the execution of <STRONG>fglBegin</STRONG> and the corresponding execution of <STRONG>fglEnd</STRONG>. <STRONG>ASSOCIATED</STRONG> <STRONG>GETS</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_ACCUM_CLEAR_VALUE</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_DEPTH_CLEAR_VALUE</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_INDEX_CLEAR_VALUE</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_COLOR_CLEAR_VALUE</STRONG> <STRONG>fglGet</STRONG> with argument <STRONG>GL_STENCIL_CLEAR_VALUE</STRONG> <STRONG>SEE</STRONG> <STRONG>ALSO</STRONG> <STRONG>fglClearAccum</STRONG>, <STRONG>fglClearColor</STRONG>, <STRONG>fglClearDepth</STRONG>, <STRONG>fglClearIndex</STRONG>, <STRONG>fglClearStencil</STRONG>, <STRONG>fglDrawBuffer</STRONG>, <STRONG>fglScissor</STRONG></PRE></BODY></HTML>⌨️ 快捷键说明
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