Tag Archives: QuickBox2D

QuickBox2D Contacts Part 1

By Zevan | September 14, 2009
CLICK HERE TO COPY
Actionscript:
  1. import com.actionsnippet.qbox.*;
  2. import Box2D.Common.Math.*;
  3.  
  4. [SWF(width = 800, height = 600, backgroundColor = 0x000000, frameRate=60)]
  5.  
  6. var sim:QuickBox2D = new QuickBox2D(this, {debug:false, frim:true});
  7.  
  8. sim.createStageWalls();
  9.  
  10. var boxA:QuickObject = sim.addBox({x:3, y:3, width:2, height:2, fillColor:0xFF0000});
  11. var boxB:QuickObject = sim.addBox({x:3, y:6, width:2, height:2, fillColor:0xFF0000});
  12.  
  13. sim.start();
  14. sim.mouseDrag();
  15.  
  16. // when boxA touches boxB a circle QuickObject is created
  17. var contacts:QuickContacts = sim.addContactListener();
  18. // listen for contact points being added
  19. contacts.addEventListener(QuickContacts.ADD, onAdd);
  20. function onAdd(evt:Event):void{
  21.     // see if this contact event is associated with boxA and boxB
  22.     if(contacts.isCurrentContact(boxA, boxB)){
  23.         // get the location of the collision in world space
  24.         var loc:b2Vec2 = contacts.currentPoint.position;
  25.         // you cannot create new QuickObjects inside this listener function
  26.         // so we just give a 5 ms delay
  27.         setTimeout(sim.addCircle, 5, {x:loc.x, y:loc.y});
  28.     }
  29. }

Note: This snippet requires QuickBox2D 1.0 or greater

I've created a few simple examples to show how to use QuickBox2D contact listeners. This is the first one. When two boxes collide circles are added to the simulation at the point of collision.


Have a look at the swf...

Posted in Box2D, QuickBox2D | Also tagged , , , | 10 Comments

QuickBox2D 1.0

By Zevan | September 14, 2009

QuickBox2D 1.0 is ready. It contains a bunch of small bug fixes and a few new features that I'll be demoing in the next few posts. The main new features relate to collision detection and simple event sequencing.

Go download it from here...

I also spent some time updating the docs.... everything is documented... I may add additional documentation text over the next few days...

A detailed tutorial for QuickBox2D is also in the works...

[EDIT]

Also, if you find any bugs send me an e-mail (see about page for e-mail)... if there are any bugs left I'd like to fix the asap.... You can also feel free to e-mail any API suggestions...

Posted in Box2D, QuickBox2D | Also tagged , , , | 2 Comments

QuickBox2D Vaguely Goldberg-esque

By Zevan | September 10, 2009
CLICK HERE TO COPY
Actionscript:
  1. import com.actionsnippet.qbox.*;
  2. import Box2D.Common.Math.*;
  3. import Box2D.Collision.Shapes.*;
  4.  
  5. [SWF(width = 800, height = 600, backgroundColor = 0xFFFFFF, frameRate=60)]
  6.  
  7. // hide everything for 300 ms
  8. visible = false;
  9. setTimeout(function():void{ visible = true}, 300);
  10.  
  11. var sim:QuickBox2D = new QuickBox2D(this, {debug:false});
  12.  
  13. sim.setDefault({fillColor:0x666666, lineAlpha:0})
  14. sim.createStageWalls();
  15.  
  16. makeLever(6 , 17.5, 9, "right", 0.7);
  17.  
  18. var circleA:QuickObject = sim.addCircle({x:2, y:3, radius:0.5, mass:4});
  19.  
  20. sim.addBox({x:15, y:12, width:2, height:0.5, density:0})
  21.  
  22. sim.addCircle({x:16, y:11, radius:0.5, mass:4, friction:0.2, fillColor:0});
  23.  
  24. sim.addBox({x:20.5, y:12, width:2, height:0.3, angle:-0.6, restitution:4.6, density:0})
  25.  
  26. makeLever(20 , 17.5, 8, "right", 1);
  27.  
  28. sim.addBox({x:9, y:9, width:2, height:0.5, density:0});
  29.  
  30. sim.addCircle({x:9, y:9, radius:0.5, mass:4, friction:0.2, fillColor:0});
  31.  
  32. sim.addBox({x:7, y:12, width:2, height:0.5, angle:-0.3, density:0, restitution:2});
  33.  
  34. sim.addBox({x:3, y:7, width:2, height:0.5, angle:Math.PI/2 - 0.22, density:0, restitution:3});
  35.  
  36. sim.addBox({x:13, y:15, width:2, height:0.5, density:0, angle:0.3, restitution:1});
  37.  
  38. sim.addBox({x:25.5, y:7, width:2, height:0.3, angle:-0.2, restitution:0.5, density:0})
  39.  
  40. sim.addBox({x:26, y:10, width:1, height:1, density:0,restitution:0.3});
  41.  
  42. sim.addBox({x:25, y:19, width:2, height:0.5, density:0, restitution:3.5, angle:-0.99});
  43.  
  44. sim.addBox({x:1, y:17, width:0.3, height:2, density:0, angle:-0.15, restitution:0.999});
  45.  
  46. sim.addBox({x:0.7, y:11, width:0.3, height:2, density:0, angle:-0.19, restitution:20})
  47.  
  48. sim.addBox({x:0.4, y:11.5, width:1, height:0.3, density:0})
  49.  
  50. function makeLever(xp:Number, yp:Number, boxWidth:Number, dir:String, off:Number=0, hasBox:Boolean=true):QuickObject{
  51.     var angle:Number, xpos:Number, weight:QuickObject
  52.     if (dir == "right"){
  53.         angle = 0.43;
  54.         xpos = xp + boxWidth / 2 - off;
  55.     }else{
  56.         angle = -0.43;
  57.         xpos = xp - boxWidth / 2 + off;
  58.     }
  59.    
  60.     if (hasBox){
  61.       weight = sim.addBox({x:xpos , y:yp, width:0.5, height:0.5, angle:angle, fillColor:0});
  62.     }
  63.  
  64.     var plank:QuickObject = sim.addBox({x:xp, y:yp, width:boxWidth, height:0.5, angle:angle});
  65.     var fulcrum:QuickObject = sim.addPoly({x:xp, y:yp, verts:[[0,0, 1,2, -1,2]], density:0})
  66.     sim.addJoint({type:"revolute", a:plank.body, b:fulcrum.body, collideConnected:false});
  67.     return weight;
  68. }
  69.  
  70. sim.start();

Just playing around with QuickBox2D and brainstorming about a few features for the first non-alpha release. If you have any feature suggestions, please feel free to leave them in the comments of this post (see the end of this post for a list features to come in QuickBox2D 1.0).


Have a look at the swf...

Upcoming Features for QuickBox2D
Simplified collision detection - will hopefully be something like hitTest for QuickObject instances.

QuickBox2D.totalTimeSteps - variable that keeps track of how many times b2World.Step() was called - useful for simple sequencing.

QuickBox2D.addTimeStepEvent(callAt:Number, callback:Function) - calls a function when QuickBox2D.totalTimeSteps is equal to the callAt value.

QuickBox2D.stepEvent - an event dispatched every time b2World.Step() is called.

New Renderer [probably not for 1.0 release]
I've been toying with the idea of creating a new renderer for QuickBox2D. Currently all rigid bodies are DisplayObjects... this is great if you plan on skinning all your rigid bodies, but if you just have flat colors it is slower than debug draw - also, debug draw mode could be optimized a good deal. So I may create a simpler, faster renderer that draws to one Graphics instance (like debug draw mode) - but abides by QuickBox2D's simple rendering params like lineColor, fillColor, lineAlpha etc...

I also need to decide how to skin the rest of the joints, currently skins only work for distance joints...

Posted in Box2D, QuickBox2D, motion | Also tagged , , , | 4 Comments

QuickBox2D create() Method

By Zevan | September 5, 2009
CLICK HERE TO COPY
Actionscript:
  1. import com.actionsnippet.qbox.*;
  2. import Box2D.Common.Math.*;
  3. import Box2D.Collision.Shapes.*;
  4.  
  5. [SWF(width = 600, height = 600, backgroundColor = 0x000000, frameRate=60)]
  6.  
  7. var sim:QuickBox2D = new QuickBox2D(this);
  8.  
  9. sim.setDefault({fillColor:0x990000, lineColor:0xFFCC00});
  10. sim.createStageWalls();
  11.  
  12. var shapeTypes:Array = ["circle", "box", "poly"];
  13. var pnts:Array = [-1, 0, -0.5, -1, 0.5, -1, 1, 0, 0,0.5, -1, 0];
  14. var poly:Array=[];
  15. for (var i:int = 0; i<20; i++){
  16.     var xp:Number = 3 + Math.random()*15;
  17.     var yp:Number = 3 + Math.random()*15;
  18.     var w:Number = 0.2 + Math.random() * 2;
  19.     var h:Number = 0.2 + Math.random() * 2;
  20.     var r:Number = 0.2 + Math.random();
  21.     var ang:Number = Math.random() * Math.PI * 2;
  22.     var index:Number = int(Math.random()*shapeTypes.length);
  23.     var s:Number = 0.3 + Math.random()*0.7;
  24.     for (var j:int = 0; j<pnts.length; j++){
  25.          poly[j] = pnts[j] * s;
  26.     }
  27.     sim.setDefault({fillColor:int(Math.random()*255) <<16, lineColor:0xFFCC00});
  28.     sim.create(shapeTypes[index], {x:xp, y:yp, width:w, height:h, angle:ang, radius:r, points:poly, wireframe:false})
  29. }
  30.  
  31. sim.start();
  32. sim.mouseDrag();

Was showing someone QuickBox2D today and created this demo after showing them a few other posts. After writing this, I realized I hadn't posted about the QuickBox2D.create() method. Which is what addBox(), addRect(), addJoint() etc.. use internally. It takes a string for the type of QuickObject you'd like to create along with the standard params Object. Note that depending on the QuickObject type certain params will simply be ignored - for example radius is ignored when the type is "box" etc...


Have a look at the swf...

Posted in Box2D, QuickBox2D | Also tagged , , | 1 Comment