- glPolygonOffset
- The glPolygonOffset function sets the scale and units OpenGL uses to calculate depth values.
- void glPolygonOffset (
- GLfloat factor,
- GLfloat units
- );
- Parameters
- factor
- Specifies a scale factor that is used to create a variable depth offset for each polygon. The initial value is zero.
- units
- Specifies a value that is multiplied by an implementation-specific value to create a constant depth offset. The initial value is 0.
- Remarks
- When GL_POLYGON_OFFSET 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 * Δz + r * units, where Δz 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.
- The glPolygonOffset function is useful for rendering hidden-line images, for applying decals to surfaces, and for rendering solids with highlighted edges.
- The glPolygonOffset function has no effect on depth coordinates placed in the feedback buffer. It also has no effect on selection.
- Note The glPolygonOffset function is only available in OpenGl version 1.1 or greater.