This is a simple narrative description of the lessonNN applications included with the Lumen library as demos. They are OpenGL tutorials taken from the NeHe Productions website, graciously converted to Ada with Lumen by the indefatigable Julian Leyh. Since all these demos are better described elsewhere, this single page will cover the (current) lot. Once more advanced lessons are contributed, we may create separate pages for those.

None of the NeHe demos accept any command-line parameters; the ones that use separate image files (currently lesson06, lesson07, and lesson08) have the pathnames hard-coded in the source. For this reason, those must be run from the lumen directory, like bin/lesson08 or whatever. All NeHe demos can be terminated with the Esc key. Full documentation of the demos can be found on the demo "manual" page.

Here's a quick rundown of what each tutorial does:

• lesson01 -- Just about the simplest possible OpenGL app. Creates a window and clears it to the default color, which these days is black. This version is more complex than it needs to be, uselessly declaring itself as an animation when its display is quite static. But it sets the stage for the more advanced tutorials to come.

• lesson02 -- Next step up the OpenGL food chain: draw some shapes, in this case one triangle and one "quad" (rectangle). Black background, white shapes.

• lesson03 -- Add color to lesson 2, with a smooth-shaded multicolored triangle, and a medium-blue quad.

• lesson04 -- Spin the shapes from lesson 3, the triangle horizontally, the quad vertially.

• lesson05 -- Introduce 3D solids. The triangle from lesson 4 becomes a pyramid, and the quad becomes a cube. Both still spinning, though the cube spins on an oblique axis for a more interesting look.

• lesson06 -- Lose the pyramid and make the cube the center of attention. Now it has a texture mapped onto it, in this case the NeHe GameDev logo, and it tumbles on all three axes.

• lesson07 -- Another textured cube, this one with a nice wooden-crate motif. Mash the up/down/left/right arrow keys to set it spinning, PgUp/PgDn to move it closer or farther away, the "l" key (lowercase L) to change the lighting, and the "t" key to cycle through various texture options. The differences between texture settings are subtle, but they're visible if you look closely.

• lesson08 -- A more sophisticated version of lesson 7, with a stained-glass texture on the cube. It accepts all the same keyboard commands that lesson07 does, and adds a 'b' command to toggle blending. Nice translucence effect, and quite different with and without lighting enabled. A very cool demo indeed.

Last Updated: 14 Dec 2011 09:32:33