grass: enable opengl

[landam]

This PR enables OpenGL support for GRASS package.

But unfortunately 3D view in GRASS GUI doesn't work:

./src/unix/glegl.cpp(391) in InitVisual(): Failed to get an
EGLConfig for the requested attributes.

This bug seems to be related to wxWidgets packaging. I tested the same version of wxWidget (3.4.2) and wxPython (4.2.1) in Nix and Debian. On Debian 3D view works as expected. So probably the problem could be related to wxWidgets packaging in Nix(?)

[imincik]

Thanks for PR.

Nix packaged software is not able to find OpenGL drivers out-of-the box. We need to use additional tools like nixGL .

Are you able to give me some copy/paste instructions how to reproduce the error you've got ?

[landam]

1. Download sample data

./result/bin/grass --tmp-location EPSG:4326 --exec g.download.location https://grass.osgeo.org/sampledata/north_carolina/nc_basic_spm_grass7.tar.gz name=nc_basic path=~/grassdata

2. Enter sample Location in GUI mode

 ./result/bin/grass --gui ~/grassdata/nc_basic/PERMANENT/

3. Load elevation map from Data tab or by

d.rast elevation

4. Switch to 3D view

[imincik]

I confirm that 3d view works when running grass with nixGL

Running on my ubuntu 22.04 machine.

nix run --override-input nixpkgs nixpkgs/20f65b86b6485decb43c5498780c223571dd56ef --impure github:guibou/nixGL#nixGLIntel -- ./result/bin/grass