In my previous post I presented an example of drawing arbitrary shapes for Box2d using the mouse. It was done using triangulation to deal with concave shapes. However, triangulation does produce a lot of vertices (as seen when holding down T), which isn’t really necessary and hogs the physics engine a lot. Since we can have up to 8 vertices per shape in a Box2d body, the number of shapes can be reduced by generating a collection of <8 vertex shapes instead of 3 vertex ones.
After som digging I found this post at Touch My Pixel’s blog, featuring a few awsome AS3 classes for doing this trick. After converting to haXe and making a minor alteration to limit the numer of vertices per shape to <8 I replaced the trianglutaion by this and it works great! It also got rid of most of the strange lines sometimes shooting out of the Box2d shapes (probably due to lots of very small angles produced by the previous triangulation method).
Also, I figured I should try out the new haxe port of Box2d recently put on googlecode by Heinz Hoelzer. So this swf is haxe all the way! :)
I also changed the style of debugDraw and added the mouse dragging feature from the box2d tests this time.
You can grab the source code for this version here if you wish.
Update: I have now made the source code compatible with hxcpp and neash, so it will compile for the C++ target. Box2D performance is about twice as fast as for the flash target. Nice!
Instructions:
* Draw bodies using your mouse.
* Hold shift while drawing to make static bodies (ground).