Really easy and quick 3d realtime interactive graphics

The talk in one sentence

Many introductions to graphics programming focus on 2D, which is a bit boring. 3D isn't much harder, particularly if you use Processing.

Reference

Processing

Cheat Sheets

Other links

Open Processing

Generative Design website (of book) with lots of source code. The book is excellent, filled with beautiful examples and clear code snippets, though is quite expensive.

Processing 2: Creative Programming Cookbook: the other book I recommended, it has 3D appearing relatively early.

Javascript version NB You can do 3D with this, though browser support may vary.

Android version Again you can do 3D things with this, along with multitouch, camera and other device sensors. You can create APKs and submit to Google Play.

Codea (for iPad) while in Lua, uses a very similar graphics API and allows you to write applications on an iPad which can be exported as an XCode project.