[Internal] OpenGL Hardware support under Unix

The information presented here is too old, and well known today. It can be found in the IDL Help.

Some, but not all Unix platforms have support for OpenGL hardware.

Discussion
IDL will attempt to detect OpenGL hardware during installation. If OpenGL is found then a library is created in the IDL_DIR/bin/bin.os directory, called gl_driver.so.

Under Unix, we currently support hardware acceleration through OpenGL shared libraries.  

On all platforms without native OpenGL hardware, a software graphics rendering library is used instead.

Note: the software graphics rendering library can be selected even if there is hardware present. There are three different ways to choose software rendering:

1- Setting the RENDERER keyword to 1 when creating an instance of an IDLgrWindow object. (Applies to an individual window.)

2- In the IDLDE select File->Preferences->Graphics and set the default graphics renderer to Software. 

3- Option 2) is limited to the IDLDE. With command line IDL the user can add the following line to ~/.Xdefaults:

idl.renderer: 1

This can be very useful as the software graphics rendering is sometimes faster than the hardware and can also generate better quality images in some cases. For more information see Performance Notes for IDL's Object Graphics.

If OpenGL is causing problems, it can be disabled completely by renaming the gl_driver.so or gl_driver.sl file can be renamed to for example gl_driver.so.old. In this case IDL will always default to software rendering, even if the IDL program explicitly calls for OpenGL (RENDERER=0).