GLAPI/glPolygonOffset: Difference between revisions
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== Function Definition == | == Function Definition == | ||
void '''glPolygonOffset'''(GLfloat | void '''glPolygonOffset'''(GLfloat {{param|factor}}, GLfloat {{param|units}}); | ||
; factor | ; factor | ||
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== Associated Gets == | == Associated Gets == | ||
{{apifunc|glIsEnabled}} with argument {{code|GL_POLYGON_OFFSET_FILL}}, {{code|GL_POLYGON_OFFSET_LINE}}, or {{code|GL_POLYGON_OFFSET_POINT}}. | |||
{{apifunc|glGet}} with argument {{code|GL_POLYGON_OFFSET_FACTOR}} or {{code|GL_POLYGON_OFFSET_UNITS}}. | |||
== See Also == | == See Also == | ||
{{apifunc|glDepthFunc}}, {{apifunc|glEnable}}, {{apifunc|glGet}}, {{apifunc|glIsEnabled}} | |||
== Copyright == | == Copyright == | ||
Revision as of 01:24, 29 April 2012
| Core in version | 4.6 | |
|---|---|---|
| Core since version | 1.0 | |
glPolygonOffset: set the scale and units used to calculate depth values
Function Definition
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 GL_POLYGON_OFFSET_FILL, GL_POLYGON_OFFSET_LINE, or GL_POLYGON_OFFSET_POINT 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.
Associated Gets
glIsEnabled with argument GL_POLYGON_OFFSET_FILL, GL_POLYGON_OFFSET_LINE, or GL_POLYGON_OFFSET_POINT.
glGet with argument GL_POLYGON_OFFSET_FACTOR or GL_POLYGON_OFFSET_UNITS.
See Also
glDepthFunc, glEnable, glGet, glIsEnabled
Copyright
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/.