When GL_POLYGON_OFFSET_FILL, GL_POLYGON_OFFSET_LINE, or GL_POLYGON_OFFSET_POINT is enabled, each fragment's value will be offset after it is interpolated from the 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.
glPolygonOffset is available only if the GL version is 1.1 or greater. glPolygonOffset has no effect on depth coordinates placed in the feedback buffer. glPolygonOffset has no effect on selection.
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/.
glPolygonOffset: man2/glPolygonOffset.xml
When GL_POLYGON_OFFSET_FILL, GL_POLYGON_OFFSET_LINE, or GL_POLYGON_OFFSET_POINT is enabled, each fragment's value will be offset after it is interpolated from the 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.
glPolygonOffset is available only if the GL version is 1.1 or greater. glPolygonOffset has no effect on depth coordinates placed in the feedback buffer. glPolygonOffset has no effect on selection.