QuickBox2D Polys

By Zevan | May 30, 2009
CLICK HERE TO COPY
Actionscript:
  1. import com.actionsnippet.qbox.*;
  2.  
  3. [SWF(backgroundColor=0x000000, width=700, height=600)]
  4.  
  5. var sim:QuickBox2D = new QuickBox2D(this);
  6.  
  7. sim.setDefault({fillColor:0x003366, lineColor:0x2B80D5});
  8. sim.createStageWalls();
  9.  
  10. var i:int = 0;
  11. for (i= 0; i<10; i++){
  12.   sim.addCircle({x:5 + i, y:7, radius:0.3, linearDamping:1, angularDamping:1, fillColor:0x78B4C2, isBullet:true}); 
  13. }
  14.  
  15. for (i= 0; i<2; i++){
  16.     var poly:Array = [];
  17.     var r:Number = 3;
  18.     var step:Number = Math.PI / 6;
  19.     for (var t:Number = 0; t<=Math.PI; t+=step){
  20.         poly.push(r * Math.cos(t));
  21.         poly.push(r * Math.sin(t));
  22.     }
  23.     r = 2;
  24.     for (t = Math.PI; t>= -step; t-=step){
  25.         poly.push(r * Math.cos(t));
  26.         poly.push(r * Math.sin(t));
  27.     }
  28.     // using points instead of verts causes QuickBox2D to triangulate the polygon
  29.     // the wireframe boolean changes rendering style for polys
  30.     sim.addPoly({x:4 + i *7, y:16, points:poly, wireframe:Boolean(i), linearDamping:1.5, angularDamping:1});
  31. }
  32.  
  33. sim.start();
  34. sim.mouseDrag();

I just uploaded QuickBox2D Alpha 106 which includes a few bug fixes and support for compound shapes and easier polys. I used the algorithm from yesterdays post to significantly simplify the way QuickBox2D handles the description of polygons.

You'll need QuickBox2D Alpha 106 or greater, if you want to test this....


or just have a look at the demo here.

This triangulation is really better suited for 3D stuff - Box2D supports multiple convex polygons in one rigid body... this algorithm makes more shapes (triangles) than Box2D needs - I'll probably swap out the algorithm in the near future.

Tomorrow I'll be posting a demo about the way QuickBox2D simplifies compound shapes. I have yet to update the docs to include the new features of Alpha 106. That will happen along with tomorrows post.

This entry was posted in Box2D, QuickBox2D, motion and tagged , . Bookmark the permalink. Post a comment or leave a trackback: Trackback URL.

4 Comments

  1. Ponce
    Posted September 30, 2009 at 6:46 am | Permalink

    Hello Zevan, I found little bug to try move objects. I do not know exactly how to reproduce it, it happens when you try to move an object against each other at some point the objects are caught in something invisible ..
    Sorry for my english

  2. Zevan
    Posted September 30, 2009 at 6:58 am | Permalink

    Hey ponce - this is a box2D thing… and you can probably fix it by turning on CCD or setting the isBullet property = true in the params object….

  3. Ponce
    Posted September 30, 2009 at 9:48 am | Permalink

    thanks!! =)

  4. Mikha
    Posted March 5, 2010 at 1:32 am | Permalink

    hi zevan

    is there a way to add the vertice just like the ordinary box2d way?

    like [[1,1],[1,-1],[-1,-1],[-1,1]]

    thanks

3 Trackbacks

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