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docs.GL

glPolygonOffset

Name

glPolygonOffset — set the scale and units used to calculate depth values

C Specification

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 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.

Version Support

OpenGL Version
Function / Feature Name 2.0 2.1 3.0 3.1 3.2 3.3 4.0 4.1 4.2 4.3 4.4 4.5
glPolygonOffset ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔
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