This is a simple narrative description of the text2 application included with the Lumen library as a demo.

The text2 demo can accept several optional command-line parameters. The first param is always the pathname of a texture-mapped font file; the second and subsequent params are values used to set the attributes used to select an OpenGL visual. If you omit the pathname, it uses fsb.txf by default; if any or all of the attribute values are omitted, it uses the same values as the library's defaults. Full documentation of the command line parameters can be found on the demo "manual" page.

You invoke text2 by typing its name, optionally followed by a font-file pathname, and further optionally followed by attribute override values, like ./text2 ../data/fsb.txf if you're sitting in the bin directory, or bin/text2 data/fsb.txf a0 d16 if you're in the lumen directory and want to select a visual different from the default, in this case one with 0 bits required for an alpha channel and 16 bits in the depth buffer. (Or, of course, simply as ./text2 or bin/text2, to use the default font and attributes.) The fsb.txf and chopin.txf files are two sample texture-mapped fonts provided for the demo programs; you can create others using the tools/make-txf tool. The "Chopin" sample font will work with text2, but it will look like ass. The FreeSans Bold font is monospaced, but Chopin is proportional, causing the animated text displayed by text2 to jump around crazily with every frame.

When run, text2 creates a light grey window with a rotating black square in the middle, which should be about half the width of the window itself. On the square, actual live program data is displayed in green letters: the frame number, and the current framerate, which should be close to 60. You can speed up or slow down the rotation of the square using the Up and Down arrow keys, or pause/restart it with the spacebar. Note that the updating of the displayed data is independent of the square's rotation. Terminate the app by pressing "q" or the Esc key, or by closing the window.

The text2 demo started life as a clone of the texture demo, but has code added to accept command-line parameters, to display program data as text, and to accept various simple keyboard commands. It was intended as a "stretch the legs" demo for Lumen, to do the sort of stuff real apps do, although as with text1 and most of the other demos before it, it uses lower-level calls than the eventual Lumen app would use. Demos for the more advanced services will come when those services are written.

Last Updated: 14 Dec 2011 09:32:33