GlPolygonOffset
_glPolygonOffset: set the scale and units used to calculate depth values
Syntax
SUB _glPolygonOffset (BYVAL factor AS SINGLE, BYVAL units AS SINGLE) void _glPolygonOffset(GLfloat factor, GLfloat units);
- factor
- Specifies a scale factor that is used to create a variable depth offset for each polygon. The initial value is 0.
- units
- Is multiplied by an implementation-specific value to create a constant depth offset. The initial value is 0.
Description
When Template:KW, Template:KW, or Template:KW is enabled, each fragment's depth value will be offset after it is interpolated from the depth 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.
_glPolygonOffset is useful for rendering hidden-line images, for applying decals to surfaces, and for rendering solids with highlighted edges.
Template:KW with argument Template:KW, Template:KW, or Template:KW.
Template:KW with argument Template:KW or Template:KW.
See also
SUB _GL Template:KW, Template:KW
Copyright 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.