Know-How für Ihr Projekt

OpenGL-HQ for SDL

OpenGL-HQ is a video "driver" for SDL that uses graphics hardware to scale the output to any size you want. It uses an algorithm similar to the popular "hq2x" scaling method, but runs it entirely on a modern graphics card, and with arbitrary scaling factors (including fractional and separate horizontal/vertical factors).

It was originally written for 2D games/emulators like dosbox, scummvm or exult. Due to the approach of implementing it as an SDL video driver, any SDL-using 2D program can be scaled. Of course, this excludes those that use SDL simply as a cross-platform wrapper around OpenGL 3D rendering or just for sound.

It should work just as well for, say, the SDL X server or VirtualBox's SDL frontend. QEmu has actually been confirmed working fine with OpenGL-HQ. Scaling legacy applications to the higher resolutions of modern displays this way reduces fuzziness, making work more ergonomic.



Warning: Some of these are several hundred kilobytes large.


There is a highly experimental, slower and slightly ugly version that works with many X11 open source drivers (those that support ARB_fragment_program, but do not yet implement EXT_frambeuffer_object). It will be used as a fallback automatically.

How to use

If you're running on Windows, there might be a prebuilt SDL.DLL included in the source archive, depending on contributors. Copy it to your application directory, overwriting the old SDL.DLL. Then read the file README contained in the archive to see how to enable it.

On all other platforms, first build the custom version, then replace your current SDL dynamic library or use your OS mechanism to override the library path on a per-program base. Usually you can just replace your system SDL installation, because as long as you don't enable OpenGL-HQ, it's just a regular copy of SDL.

The README included in the tarball contains more detailed instructions.


In case of trouble, read the file README contained in the archive. It addresses most problems you might encounter.

Downloads / Version History

Since updates usually only fix bugs or improve compatibility, there is no detailed version history. Check the archive directory and pick the newest file.


SDL OpenGL-HQ is distributed under the terms of the GNU Lesser General Public License (LGPL) Version 2 or later.