<HTML> <BODY> <PRE> <STRONG>NAME</STRONG> <STRONG>glPolygonOffset</STRONG> - set the scale and units used to calculate depth values <STRONG>C</STRONG> <STRONG>SPECIFICATION</STRONG> void <STRONG>glPolygonOffset</STRONG>( GLfloat <EM>factor</EM>, GLfloat <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>glPolygonOffset</STRONG> is useful for rendering hidden-line images, for applying decals to surfaces, and for rendering solids with highlighted edges. <STRONG>NOTES</STRONG> <STRONG>glPolygonOffset</STRONG> is available only if the GL version is 1.1 or greater. <STRONG>glPolygonOffset</STRONG> has no effect on depth coordinates placed in the feedback buffer. <STRONG>glPolygonOffset</STRONG> has no effect on selection. <STRONG>ERRORS</STRONG> <STRONG>GL_INVALID_OPERATION</STRONG> is generated if <STRONG>glPolygonOffset</STRONG> is executed between the execution of <STRONG>glBegin</STRONG> and the corresponding execution of <STRONG>glEnd</STRONG>. <STRONG>ASSOCIATED</STRONG> <STRONG>GETS</STRONG> <STRONG>glIsEnabled</STRONG> with argument <STRONG>GL_POLYGON_OFFSET_FILL</STRONG>, <STRONG>GL_POLYGON_OFFSET_LINE</STRONG>, or <STRONG>GL_POLYGON_OFFSET_POINT</STRONG>. <STRONG>glGet</STRONG> with argument <STRONG>GL_POLYGON_OFFSET_FACTOR</STRONG> or <STRONG>GL_POLYGON_OFFSET_UNITS</STRONG>. <STRONG>SEE</STRONG> <STRONG>ALSO</STRONG> <STRONG>glDepthFunc</STRONG>, <STRONG>glDisable</STRONG>, <STRONG>glEnable</STRONG>, <STRONG>glGet</STRONG>, <STRONG>glIsEnabled</STRONG>, <STRONG>glLineWidth</STRONG>, <STRONG>glStencilOp</STRONG>, <STRONG>glTexEnv</STRONG> </PRE> </BODY> </HTML>