pouët.net

Does anyone reading this know any program that allows you to draw diagrams in a precise way, like measuring angles, snapping to tangents, etc? Something cad like, but simple.

Stuff like drawing a precise schematic for sphere tracing for example.

I don't know if this one would do the job but definately worth a try.



"The Magna Doodle was of course designed as a child’s toy, but it has also proved very useful to scuba divers, who use it to write messages to each other when under water."

How about Draftsight? The snap tools in it are ace, though it's only 2D..

If it doesn't have to look academically, you might wanna check out Google SketchUp. Somewhat CAD-like, measuring, snapping, simple. You never know.

If you're heading for 2D, Inkscape (vector-based illustration tool) might be worth a try.

I'll try draftsight.
I couldn't make what I was trying to do with Inkscape, but it might work with a little bit of patience.

kseg

Probably won't help at all, but it's awesome.

I used Ipe and liked it.

And I'll try Ipe now... CAD seems a bit overkill for this :D

TeX?

C.a.R.?

Maybe it's not exactly what you're looking for, but I remember Cabri II Plus from way back in school. It's a geometry learning tool that's based mainly around concepts more than numbers. You can do things like drawing an angle, drawing a line at the angle bisection and then moving the two lines in the original angle and have the bisection follow. Of course you can do much more complex things as well.
It's probably crude compared to some of the other programs linked in this thread, but for me, Cabri II Plus is big-time nostalgia.

Another Cabri like : GeoGebra. I often use it with 12-16 years old pupils. It can output in TeX format (pstricks).

Also French wikipedia page about dynamical geometry has links to many of them. C.a.R seems to be first (1993, Cabri 1994)?
DrGeo was made by Hilaire Fernandes, aka Hil/Arm's Tech, yoohoo! :)