glPolygonOffset
, glPolygonOffsetx
- set the scale and units used to calculate depth values
void glPolygonOffset(GLfloat factor, GLfloat units) void glPolygonOffsetx(GLfixed factor, GLfixed 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.
When GL_POLYGON_OFFSET_FILL
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 m * factor + r * units, where m 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 for applying decals to surfaces.
Copyright © 2003-2004 Silicon Graphics, Inc.
This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.