Add configure option for --with-demo

[behdad]

Copying comments from the Google Code bug, just for future reference:

Reported by kcconley, Oct 30, 2012
Add support to skip demo and its dependencies during 'configure' and to not build demo when running 'make'.
Nov 1, 2012 Delete comment Project Member #1 behdad.esfahbod
Fair enough.  However, the dependencies shouldn't pose a build fail.  If you don't mind me asking, what''s the primary reason you need this?
Nov 1, 2012 Delete comment #2 kcconley
I built glyphy for iOS. I just needed to link to libglyphy. I refactored (hacked) the demo to run on iOS (without GLUT). The repo version of demo won't build because GLUT doesn't exist on iOS.

BTW. Demo runs SLOW on my iPod 3G. ~3 FPS
Nov 1, 2012 Delete comment #3 behdad@chromium.org
Interesting.  If you have patches of the changes I'd be happy to take them.
Nov 1, 2012 Delete comment #4 kcconley
I'd be happy to give it to you. But its kind of an embarassing mess right now. I just wanted to see the performance so I spent an hour or so getting it running. I have an Xcode project which is more or less a hacked version of the demo files and some platform-specific stuff. I have it linking to libglyphy which I am building from the command-line. Nothing that resembles a 'patch' at this point.
Nov 1, 2012 Delete comment #5 behdad@chromium.org
Right.  That's what I expected.  Would be interesting to see the number on iPhone 5.  I'm more interested seeing numbers on Android, and have not got the time to port yet.
Nov 1, 2012 Delete comment #6 kcconley
I will try it on the 4S this weekend. Was hoping it would be faster than it was. Its too heavy in the fragment shader. I would like to make it faster. :-/ You guys working on any major speed improvements?
Nov 1, 2012 Delete comment Project Member #7 behdad.esfahbod
I'm not actively working on it right now, but may do next year.  However, most of my ideas involve reducing texture fetches in exchange of more work in the fragment shader :(.  The thing is, I don't have a test environment that is weak on the shader operations, so I can't test any change.

On my two testing machines (ThinkPad T530, and Macbook Air), the demo runs at over 60fps fullscreen...
Nov 1, 2012 Delete comment #8 kcconley
You can simply try to render the demo geometry X times per frame. Increase X until the framerate drops to like 20 fps or something.
Dec 6, 2012 Delete comment #9 behdad@chromium.org
So, any chance you can run this on an iPhone5?

[mmohrhard]

I'll implement that in a bit as I'll need it anyway for the LibreOffice build.

[behdad]

Thanks Markus!

[matthiasclasen]

The recently added meson build has a demo option