Name
gl.PolygonOffset -- set the scale and units used to calculate depth values
Synopsis
gl.PolygonOffset(factor, units)
Function
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 * delta(Z) + r * units , where delta(Z) 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.

gl.PolygonOffset() is useful for rendering hidden-line images, for applying decals to surfaces, and for rendering solids with highlighted edges.

gl.PolygonOffset() has no effect on depth coordinates placed in the feedback buffer.

gl.PolygonOffset() has no effect on selection.

Please consult an OpenGL reference manual for more information.

Inputs
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
Errors
#GL_INVALID_OPERATION is generated if gl.PolygonOffset() is executed between the execution of gl.Begin() and the corresponding execution of gl.End().

Associated gets
gl.IsEnabled() with argument #GL_POLYGON_OFFSET_FILL, #GL_POLYGON_OFFSET_LINE, or #GL_POLYGON_OFFSET_POINT.

gl.Get() with argument #GL_POLYGON_OFFSET_FACTOR or #GL_POLYGON_OFFSET_UNITS.


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