📄 fglpolygonstipple.html
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<HTML><BODY><PRE> <STRONG>NAME</STRONG> <STRONG>fglPolygonStipple</STRONG> - set the polygon stippling pattern <STRONG>FORTRAN</STRONG> <STRONG>SPECIFICATION</STRONG> SUBROUTINE <STRONG>fglPolygonStipple</STRONG>( CHARACTER*256 <EM>mask</EM> ) <STRONG>PARAMETERS</STRONG> <EM>mask</EM> Specifies a pointer to a 32x32 stipple pattern that will be unpacked from memory in the same way that <STRONG>fglDrawPixels</STRONG> unpacks pixels. <STRONG>DESCRIPTION</STRONG> Polygon stippling, like line stippling (see <STRONG>fglLineStipple</STRONG>), masks out certain fragments produced by rasterization, creating a pattern. Stippling is independent of polygon antialiasing. <EM>mask</EM> is a pointer to a 32x32 stipple pattern that is stored in memory just like the pixel data supplied to a <STRONG>fglDrawPixels</STRONG> call with <EM>height</EM> and <EM>width</EM> both equal to 32, a pixel format of <STRONG>GL_COLOR_INDEX</STRONG>, and data type of <STRONG>GL_BITMAP</STRONG>. That is, the stipple pattern is represented as a 32x32 array of 1-bit color indices packed in unsigned bytes. <STRONG>fglPixelStore</STRONG> parameters like <STRONG>GL_UNPACK_SWAP_BYTES</STRONG> and <STRONG>GL_UNPACK_LSB_FIRST</STRONG> affect the assembling of the bits into a stipple pattern. Pixel transfer operations (shift, offset, pixel map) are not applied to the stipple image, however. To enable and disable polygon stippling, call <STRONG>fglEnable</STRONG> and <STRONG>fglDisable</STRONG> with argument <STRONG>GL_POLYGON_STIPPLE</STRONG>. Polygon stippling is initially disabled. If it's enabled, a rasterized polygon fragment with window coordinates x and y is sent to the next stage of the GL if and only ifwthe (<STRONG>x</STRONG> mod 32)th bit in the (y mod 32)th row of the stipple pa<STRONG>t</STRONG>tern is 1 (one). When p<STRONG>o</STRONG>lygon stippling is disabled, it is as if the stipple pattern consists of all 1's. <STRONG>ERRORS</STRONG> <STRONG>GL_INVALID_OPERATION</STRONG> is generated if <STRONG>fglPolygonStipple</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>fglGetPolygonStipple</STRONG> <STRONG>fglIsEnabled</STRONG> with argument <STRONG>GL_POLYGON_STIPPLE</STRONG> <STRONG>SEE</STRONG> <STRONG>ALSO</STRONG> <STRONG>fglDrawPixels</STRONG>, <STRONG>fglLineStipple</STRONG>, <STRONG>fglPixelStore</STRONG>, <STRONG>fglPixelTransfer</STRONG></PRE></BODY></HTML>⌨️ 快捷键说明
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