Category Archives: motion

QuickBox2D Connect to GroundBody

By Zevan | August 13, 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:0x113366, fillAlpha:0.8, lineColor:0x3355AA});
  8.  
  9. sim.createStageWalls();
  10.  
  11. var boxA:QuickObject = sim.addBox({x:10, y:8, width:4, height:0.5, angularDamping:1});
  12. var boxB:QuickObject = sim.addBox({x:7, y:8, width:3, height:0.25, angle:-.5, angularDamping:1});
  13. var boxC:QuickObject = sim.addBox({x:12, y:2, width:2, height:1});
  14.  
  15. var rev:QuickObject = sim.addJoint({type:"revolute", a:boxA.body, b:sim.w.GetGroundBody()});
  16. // add a red dot to boxA
  17. with (boxA.userData.graphics) lineStyle(), beginFill(0xFF0000), drawCircle(0,0,2);
  18.  
  19. var rev2:QuickObject = sim.addJoint({type:"revolute", a:boxB.body, b:sim.w.GetGroundBody()});
  20. with (boxB.userData.graphics) lineStyle(), beginFill(0xFF0000), drawCircle(0,0,2);
  21.  
  22. sim.start();
  23. sim.mouseDrag();

In order to use gear joints (covered in tomorrows post) you'll need to know how to connect to the ground body...

Check out the swf...

Also posted in Box2D, QuickBox2D | Tagged , , , , | 3 Comments

QuickBox2D Revolute Walker

By Zevan | August 12, 2009
CLICK HERE TO COPY
Actionscript:
  1. import com.actionsnippet.qbox.*;
  2. import Box2D.Dynamics.Joints.*;
  3.  
  4. [SWF (backgroundColor=0x222222, width=700, height=600)]
  5.  
  6. var sim:QuickBox2D = new QuickBox2D(this);
  7.  
  8. sim.setDefault({fillColor:0x000000, lineColor:0xCCCCCC});
  9. sim.createStageWalls();
  10.  
  11. var legA:QuickObject = sim.addBox({x:5, y:11, width:2, height:0.2,groupIndex:-2});
  12. var three:QuickObject = sim.addBox({x:6.8 + 1.8, y:11, width:2, height:0.2,groupIndex:-2});
  13. var legB:QuickObject = sim.addBox({x:6.8, y:11, width:2, height:0.5,groupIndex:-2});
  14. sim.setDefault({type:"revolute"});
  15.  
  16. var anchorX:Number = legA.x + (legB.x - legA.x) / 2;
  17. var anchorY:Number = legA.y;
  18. var revJointA:QuickObject = sim.addJoint({a:legA.body, b:legB.body, x1:anchorX, y1:anchorY,enableMotor:true, maxMotorTorque:80});
  19.  
  20. anchorX = legB.x + (three.x - legB.x) / 2;
  21.  
  22. var revJointB:QuickObject = sim.addJoint({a:legB.body, b:three.body, x1:anchorX, y1:anchorY, enableMotor:true, maxMotorTorque:80});
  23.  
  24. setWalkDir(6);
  25. addEventListener(Event.ENTER_FRAME, onLoop);
  26. function onLoop(evt:Event):void {
  27.   if (legB.x <4){
  28.     setWalkDir(6);  
  29.   }else if (legB.x> 19){
  30.     setWalkDir(-6);  
  31.   }
  32. }
  33. function setWalkDir(dir:Number):void{
  34.     var j:b2RevoluteJoint;
  35.     j = revJointA.joint as b2RevoluteJoint
  36.     j.SetMotorSpeed(dir);
  37.     j = revJointB.joint as b2RevoluteJoint
  38.     j.SetMotorSpeed(dir * -1);
  39. }
  40.  
  41. sim.start();
  42. sim.mouseDrag();

This demo is a bit more complex than the last two - mostly because it makes use of motors...


Have a look at the swf...

Also posted in Box2D, QuickBox2D | Tagged , , , , | 3 Comments

QuickBox2D Pulley Joint

By Zevan | August 11, 2009
CLICK HERE TO COPY
Actionscript:
  1. import com.actionsnippet.qbox.*;
  2. import Box2D.Common.Math.*;
  3.  
  4. [SWF (backgroundColor=0x000000, width=700, height=600)]
  5.  
  6. var sim:QuickBox2D = new QuickBox2D(this);
  7.  
  8. sim.setDefault({fillColor:0x113366, fillAlpha:0.8, lineColor:0x3355AA});
  9.  
  10. sim.createStageWalls();
  11.  
  12. var boxA:QuickObject = sim.addBox({x:10, y:8, fixedRotation:true});
  13. var boxB:QuickObject = sim.addBox({x:14, y:8, width:2,  fixedRotation:true});
  14.  
  15. sim.addJoint({type:"pulley", a:boxA.body, b:boxB.body, groundAnchor1:new b2Vec2(boxA.x, 2), groundAnchor2:new b2Vec2(boxB.x, 2)});
  16.  
  17. sim.start();
  18. sim.mouseDrag();

QuickBox2D pulley joint demo. This post is really meant to serve as part of the docs so it may seem a bit boring in its simplicity...

Have a look at the swf...

Also posted in Box2D, QuickBox2D | Tagged , , , , | 4 Comments

QuickBox2D Revolute Ragdoll

By Zevan | August 9, 2009
CLICK HERE TO COPY
Actionscript:
  1. import com.actionsnippet.qbox.*;
  2. import Box2D.Common.Math.*;
  3.  
  4. [SWF (backgroundColor=0x000000, width=700, height=600, frameRate=60)]
  5.  
  6. var sim:QuickBox2D = new QuickBox2D(this,{debug:false, frim:true, gravityY:1});
  7.  
  8. sim.setDefault({fillColor:0x113366, fillAlpha:0.8, lineColor:0x3355AA});
  9.  
  10. sim.createStageWalls();
  11.  
  12. var circle:QuickObject = sim.addCircle({x:10, y:10, radius:3});
  13. var head:QuickObject = sim.addCircle({x:5, y:5, radius:0.5});
  14. var torsoA:QuickObject = sim.addBox({x:5, y:6, width:1.5, height:0.8})
  15. var torsoB:QuickObject = sim.addBox({x:5, y:6.5, width:1.25, height:0.8})
  16. var torsoC:QuickObject = sim.addBox({x:5, y:7, width:1.0, height:0.8})
  17. var pelvis:QuickObject = sim.addBox({x:5, y:7.5, width:1.0, height:0.8})
  18. var leftLegA:QuickObject = sim.addBox({x:4.75, y:8.5, width:0.4, height:1.75});
  19. var leftLegB:QuickObject = sim.addBox({x:4.75, y:9.75, width:0.4, height:1.5});
  20. var rightLegA:QuickObject = sim.addBox({x:5.29, y:8.5, width:0.4, height:1.75});
  21. var rightLegB:QuickObject = sim.addBox({x:5.29, y:9.75, width:0.4, height:1.5});
  22. var leftArmA:QuickObject = sim.addBox({x:3.6, y:5.8, width:1.3, height:0.35});
  23. var leftArmB:QuickObject = sim.addBox({x:2.5, y:5.8, width:1.25, height:0.35});
  24. var rightArmA:QuickObject = sim.addBox({x:6.4, y:5.8, width:1.3, height:0.35});
  25. var rightArmB:QuickObject = sim.addBox({x:7.5, y:5.8, width:1.25, height:0.35});
  26.  
  27. torsoA.body.SetLinearVelocity(new b2Vec2(0, 50));
  28.  
  29. var anchor:b2Vec2 = new b2Vec2();
  30. function connect(a:QuickObject, b:QuickObject, lower:Number, upper:Number, offX:Number=0, offY:Number = 0):QuickObject{
  31.      var min:Number = Math.min(a.y, b.y);
  32.      var max:Number = Math.max(a.y, b.y);
  33.      anchor.y = min + (max - min) * 0.5 + offY;
  34.      min = Math.min(a.x, b.x);
  35.      max = Math.max(a.x, b.x);
  36.      anchor.x = min + (max - min) * 0.5 + offX;
  37.     return sim.addJoint({a:a.body, b:b.body, x1:anchor.x, y1:anchor.y, lowerAngle:lower, upperAngle:upper});
  38. }
  39.  
  40. sim.setDefault({type:"revolute", collideConnected:false, enableLimit:true, lineColor:0xFFFFFF});
  41.  
  42. connect(head, torsoA, -.2, .2);
  43. connect(torsoA, torsoB,-.2, .2);
  44. connect(torsoC, torsoB,-.2, .2);
  45. connect(torsoC, pelvis,-.2, .2);
  46.  
  47. connect(pelvis, leftLegA, -1, 1, 0, -0.5);
  48. connect(leftLegA, leftLegB, -1, 1);
  49.  
  50. connect(pelvis, rightLegA, -1, 1, 0, -0.5);
  51. connect(rightLegA, rightLegB, -1, 1);
  52.  
  53. connect(torsoA, leftArmA, -2, 1);
  54. connect(leftArmA, leftArmB, -2, 1);
  55.  
  56. connect(torsoA, rightArmA, -1, 2)
  57. connect(rightArmA, rightArmB, -1, 2)
  58.  
  59. sim.start();
  60. sim.mouseDrag();

QuickBox2D alpha 108 is finally finished and different types of joints are now possible. I'll be auto-posting joint demos over the next few days for each type of Box2D joint. Box2D joints are pretty confusing, I struggled a bit to decide on a good way to handle them in QuickBox2D, any suggestions are welcome.


Have a look at the swf:

Also posted in Box2D, QuickBox2D | Tagged , , , , | 1 Comment