Contents

• Dependencies
• Overview
• New Procedures and Functions
• New Tokens
• Errors
• New State
• New Implementation Dependent State

Dependencies

None

Overview

The depth values of fragments generated by rendering polygons are displaced by an amount that is proportional to the maximum absolute value of the depth slope of the polygon, measured and applied in window coordinates. This displacement allows lines (or points) and polygons in the same plane to be rendered without interaction -- the lines rendered either completely in front of or behind the polygons (depending on the sign of the offset factor). It also allows multiple coplanar polygons to be rendered without interaction, if different offset factors are used for each polygon. Applications include rendering hidden-line images, rendering solids with highlighted edges, and applying `decals' to surfaces.

New Procedures and Functions

void PolygonOffsetEXT(float factor, float bias);

New Tokens

Accepted by the

<cap>

parameter of Enable, Disable, and IsEnabled, and by the

<pname>

parameter of GetBooleanv, GetIntegerv, GetFloatv, and GetDoublev:

|POLYGON_OFFSET_EXT | 0x8037| |:-------------------------------|:--------|

Accepted by the

<pname>

parameter of GetBooleanv, GetIntegerv, GetFloatv, and GetDoublev:

|POLYGON_OFFSET_FACTOR_EXT | 0x8038| |:--------------------------------|:--------| |POLYGON_OFFSET_BIAS_EXT | 0x8039 |

Errors

INVALID_OPERATION is generated if PolygonOffsetEXT is called between execution of Begin and the corresponding execution of End.

New State

| Get Value | Get Command | Type | Initial Value | |:--------------|:----------------|:---------|:------------------| |POLYGON_OFFSET_EXT |IsEnabled | B |False | |POLYGON_OFFSET_FACTOR_EXT|GetFloatv |R | 0 | |POLYGON_OFFSET_BIAS_EXT |GetFloatv | R | 0 |

New Implementation Dependent State

None