📄 fglpolygonoffset.html
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<HTML><BODY><PRE> <STRONG>NAME</STRONG> <STRONG>fglPolygonOffset</STRONG> - set the scale and units used to calculate depth values <STRONG>FORTRAN</STRONG> <STRONG>SPECIFICATION</STRONG> SUBROUTINE <STRONG>fglPolygonOffset</STRONG>( REAL*4 <EM>factor</EM>, REAL*4 <EM>units</EM> ) <STRONG>PARAMETERS</STRONG> <EM>factor</EM> Specifies a scale factor that is used to create a variable depth offset for each polygon. The initial value is 0. <EM>units</EM> Is multiplied by an implementation-specific value to create a constant depth offset. The initial value is 0. <STRONG>DESCRIPTION</STRONG> When <STRONG>GL_POLYGON_OFFSET</STRONG> is enabled, each fragment's <EM>depth</EM> value will be offset after it is interpolated from the <EM>depth</EM> values of the appropriate vertices. The value of the offset is factor * DZ + r * units, where DZ is a measurement of the change in depth relative to the screen area of the polygon, and r is the smallest value that is guaranteed to produce a resolvable offset for a given implementation. The offset is added before the depth test is performed and before the value is written into the depth buffer. <STRONG>fglPolygonOffset</STRONG> is useful for rendering hidden-line images, for applying decals to surfaces, and for rendering solids with highlighted edges. <STRONG>NOTES</STRONG> <STRONG>fglPolygonOffset</STRONG> is available only if the GL version is 1.1 or greater. <STRONG>fglPolygonOffset</STRONG> has no effect on depth coordinates placed in the feedback buffer. <STRONG>fglPolygonOffset</STRONG> has no effect on selection. <STRONG>ERRORS</STRONG> <STRONG>GL_INVALID_OPERATION</STRONG> is generated if <STRONG>fglPolygonOffset</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>fglIsEnabled</STRONG> with argument <STRONG>GL_POLYGON_OFFSET_FILL</STRONG>, <STRONG>GL_POLYGON_OFFSET_LINE</STRONG>, or <STRONG>GL_POLYGON_OFFSET_POINT</STRONG>. <STRONG>fglGet</STRONG> with argument <STRONG>GL_POLYGON_OFFSET_FACTOR</STRONG> or <STRONG>GL_POLYGON_OFFSET_UNITS</STRONG>. <STRONG>SEE</STRONG> <STRONG>ALSO</STRONG> <STRONG>fglDepthFunc</STRONG>, <STRONG>fglDisable</STRONG>, <STRONG>fglEnable</STRONG>, <STRONG>fglGet</STRONG>, <STRONG>fglIsEnabled</STRONG>, <STRONG>fglLineWidth</STRONG>, <STRONG>fglStencilOp</STRONG>, <STRONG>fglTexEnv</STRONG></PRE></BODY></HTML>⌨️ 快捷键说明
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