Intel's Mesa Driver Tacks On Another GL Extension For Old Hardware

Written by Michael Larabel in Mesa on 5 October 2015 at 06:54 PM EDT. 14 Comments
The OpenGL EXT_polygon_offset_clamp extension has been supported in mainline Mesa for the Intel i965 Mesa DRI driver for some time while now this extension is supported for older Intel Gen 4/5 hardware.

If you're stuck with an older Intel Gen 4 or Gen 5 graphics processor, with this commit the GL_EXT_polygon_offset_clamp extension is supported. The patch for this enablement on the older Intel IGPs was done by prolific community contributor Ilia Mirkin as opposed to being from the Intel OTC staff.

As described at, "This extension adds a new parameter to the polygon offset function that clamps the calculated offset to a minimum or maximum value. The clamping functionality is useful when polygons are nearly parallel to the view direction because their high slopes can result in arbitrarily large polygon offsets. In the particular case of shadow mapping, the lack of clamping can produce the appearance of unwanted holes when the shadow casting polygons are offset beyond the shadow receiving polygons, and this problem can be alleviated by enforcing a maximum offset value."
Related News
About The Author
Michael Larabel

Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

Popular News This Week