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Frequently Asked Questions


How do I install GEM and Pd on linux? !

See the readme for installing Pd.

GEM should be at

chdir to /src/Gnu and build Gem following the instructions in the (./configure; make)

If you then make install, then all of the example files and documention should be put in the correct locations.

if you are using debian, Gem should be available via apt

if you are using an rpm-based distribution, check out the builds at planetCCRMA

This FAQ applies to: 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.888

Why is GEM slow on Linux?

It is because you have to use Mesa, which might be running in software.

Mesa is an awesome package by "Brian Paul" which "emulates" OpenGL.

Basically, it is a fully compliant OpenGL package, but it isn't officially sanctioned by the OpenGL ARB, such, it is doesn't have the OpenGL name.

There is an acceleration package for the many graphics card, but I don't know anything about it.

nVidia is being very supportive of Linux: their TNT2 and GeForce cards work under Linux with hardware-acceleration of openGL. (but the drivers are proprietary)

radeon cards should also be supported very well under linux (even with open-source drivers)

If I resize the window, everything looks strange.

GEM doesn't trap resize events in IRIX or Linux (this is not a problem in WinNT).

This means that OpenGL doesn't have the correct information to render properly.

If you want to resize the window, send a dimen x y message to gemwin before you create the window.

How do I get GEM for linux?

There are no linux binaries available on the website...How do I get Gem for linux?

Since Gem has a lot of external dependencies and there are a lot of different linux distributions, many of them providing different libraries, there are usually no pre-built binaries for Gem on linux.

Instead, you are invited to get the latest sources of Gem and build it yourself.

Getting the sources:

  • if there is a source-package for a certain release, grab it, extract it, cd into the /src directory, and run
    • ./configure (optionally with some flags) and
    • make
  • if there is no source-package available get the latest and greatest sources via CVS, cd into the /src directory, and run
    • aclocal,
    • autoconf,
    • ./configure (optionally with some flags) and
    • make

Why does Gem crash when creating the Gem-window? !

When I try to create a Gem-window, my X-server crashes (or worse)? btw, I am using Ubuntu/hoary with fglrx drivers.


try setting the environment variable GEM_SINGLE_CONTEXT to 1


Gem establishes an (invisible) openGL-context at startup, even if no Gem-window is created yet. When you create the Gem-window, a 2nd openGL-context is used (which shares some properties with the invisible context).

For some reasons this seems to be not possible with some gfx-drivers (e.g. ATI's proprietary fglrx drivers) and some window-managers (i suspect compiz/beryll), leading to crashes of the X-server and/or system freezes.

The current workaround is to set the environment variable GEM_SINGLE_CONTEXT=1, which prevents this dual-context magic.


  • if you are starting Pd from the bash, you can start Pd/Gem with GEM_SINGLE_CONTEXT=1 pd -lib Gem
  • on bash, you can also set this permanently by adding a the line export GEM_SINGLE_CONTEXT=1 to either ~/.bashrc (the bash-configuration file in your home-directory) or to /etc/bash.bashrc (to set it for all users)

This FAQ applies to: 0.91

Why does Gem crash when sending [destroy( to [gemwin]?

After working a bit with Gem with my intel-graphics card, I incidentally closed the Gem-window by sending a [destroy( message to the [gemwin] object. This crashed Pd with a "Segmentation Fault".

Hmm, even though this question is frequently asked, there is no satisfying answer to it yet. Chances are high that something will change if you use the GEM_SINGLE_CONTEXT environmental variable, as described here

This FAQ applies to: 0.91.1

by IOhannes m zmoelnig last modified 2007-07-18 11:49 AM

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