xorg

cd ogldemo
ss gencyldemo.ss
If you have the error
Assertion failed: (pthreadret == 0), function _xcb_in_wake_up_next_reader, file xcb_in.c, line 926.
then you must change the version of
xorg-xcb-proto, xorg-libxcb
to 1.13 from 1.14.
Do the following.
git clone --single-branch https://github.com/macports/macports-ports.git
cd macports-ports
git checkout b0ba9280eab572558a893dd27e17f1ceade9ab38
cd x11/xorg-libxcb
sudo port install
cd ../xorg-xcb-proto
sudo port install
And then do
port installed xorg-xcb-proto xorg-libxcb
you see version 1.13 are active.

no appropriate RGB visual

Still, you may have this error. Then do
sudo port install mesa