📄 fglreadbuffer.html
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<HTML><BODY><PRE> <STRONG>NAME</STRONG> <STRONG>fglReadBuffer</STRONG> - select a color buffer source for pixels <STRONG>FORTRAN</STRONG> <STRONG>SPECIFICATION</STRONG> SUBROUTINE <STRONG>fglReadBuffer</STRONG>( INTEGER*4 <EM>mode</EM> ) <STRONG>PARAMETERS</STRONG> <EM>mode</EM> Specifies a color buffer. Accepted values are <STRONG>GL_FRONT_LEFT</STRONG>, <STRONG>GL_FRONT_RIGHT</STRONG>, <STRONG>GL_BACK_LEFT</STRONG>, <STRONG>GL_BACK_RIGHT</STRONG>, <STRONG>GL_FRONT</STRONG>, <STRONG>GL_BACK</STRONG>, <STRONG>GL_LEFT</STRONG>, <STRONG>GL_RIGHT</STRONG>, and <STRONG>GL_AUX</STRONG><EM>i</EM>, where <EM>i</EM> is between 0 and <STRONG>GL_AUX_BUFFERS</STRONG> -1. <STRONG>DESCRIPTION</STRONG> <STRONG>fglReadBuffer</STRONG> specifies a color buffer as the source for subsequent <STRONG>fglReadPixels</STRONG>, <STRONG>fglCopyTexImage1D</STRONG>, <STRONG>fglCopyTexImage2D</STRONG>, <STRONG>fglCopyTexSubImage1D</STRONG>, <STRONG>fglCopyTexSubImage2D</STRONG>, and <STRONG>fglCopyPixels</STRONG> commands. <EM>mode</EM> accepts one of twelve or more predefined values. (<STRONG>GL_AUX0</STRONG> through <STRONG>GL_AUX3</STRONG> are always defined.) In a fully configured system, <STRONG>GL_FRONT</STRONG>, <STRONG>GL_LEFT</STRONG>, and <STRONG>GL_FRONT_LEFT</STRONG> all name the front left buffer, <STRONG>GL_FRONT_RIGHT</STRONG> and <STRONG>GL_RIGHT</STRONG> name the front right buffer, and <STRONG>GL_BACK_LEFT</STRONG> and <STRONG>GL_BACK</STRONG> name the back left buffer. Nonstereo double-buffered configurations have only a front left and a back left buffer. Single-buffered configurations have a front left and a front right buffer if stereo, and only a front left buffer if nonstereo. It is an error to specify a nonexistent buffer to <STRONG>fglReadBuffer</STRONG>. <EM>mode</EM> is initially <STRONG>GL_FRONT</STRONG> in single-buffered configurations, and <STRONG>GL_BACK</STRONG> in double-buffered configurations. <STRONG>ERRORS</STRONG> <STRONG>GL_INVALID_ENUM</STRONG> is generated if <EM>mode</EM> is not one of the twelve (or more) accepted values. <STRONG>GL_INVALID_OPERATION</STRONG> is generated if <EM>mode</EM> specifies a buffer that does not exist. <STRONG>GL_INVALID_OPERATION</STRONG> is generated if <STRONG>fglReadBuffer</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_READ_BUFFER</STRONG> <STRONG>SEE</STRONG> <STRONG>ALSO</STRONG> <STRONG>fglCopyPixels</STRONG>, <STRONG>fglCopyTexImage1D</STRONG>, <STRONG>fglCopyTexImage2D</STRONG>, <STRONG>fglCopyTexSubImage1D</STRONG>, <STRONG>fglCopyTexSubImage2D</STRONG>, <STRONG>fglDrawBuffer</STRONG>, <STRONG>fglReadPixels</STRONG></PRE></BODY></HTML>⌨️ 快捷键说明
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