WarningThis was tested on Ubuntu 9.04 and 9.10. The breakable polygons feature is highly unstable; use at your own risk (will crash). This project is in its very early stages, and is better used as a point of reference than a useful program.
IntroPhed is an open source cross-platform map editor with a built-in physics simulator, written in C++. It uses Qt (Nokia) for the GUI, and Box2D (Erin Catto) for physics. It is being developed by Mark Bayazit.
Current FeaturesSupport for non-convex and clockwise polygons (not natively supported by Box2D) All Box2D properties are editable (friction, restitution, etc.) Cross-platform Planned FeaturesEdge chains Freehand shape drawing Moving/rotating objects Joints (lots!) Minimap History (undo) Textures Presets and premade objects Loading/saving BuildingTested on Qt4.5, Box2D rev10, Ubuntu 9.04 64-bit. Built using NetBeans 6.8m1 (Aug 2, 2009).
There's a Makefile that might work...