More z-sorting

By Zevan | September 1, 2009
CLICK HERE TO COPY
Actionscript:
  1. [SWF(width = 500, height=500, backgroundColor = 0x333333)]
  2. x = stage.stageWidth / 2;
  3. y = stage.stageHeight / 2;
  4.  
  5.  
  6. var polyNum:int = 3000;
  7. // standard Vectors for using drawTriangles
  8. var verts:Vector.<Number> = new Vector.<Number>();
  9. var pVerts:Vector.<Number>;
  10. var uvts:Vector.<Number> = new Vector.<Number>();
  11. var indices:Vector.<int> = new Vector.<int>();
  12. // needed for z-sorting
  13. var sortedIndices:Vector.<int>;
  14. var faces:Array = [];
  15.  
  16. // we'll use this for tranforming points
  17. // and as the transormation matrix for our render
  18. var m:Matrix3D = new Matrix3D();
  19.  
  20. // plot a poly
  21. var poly:Vector.<Number>;
  22. poly = Vector.<Number>([ 0, 0, 0,
  23.                         10, 0, 0,
  24.                         0,10, 0]);
  25.  
  26. // temp vect for any transformed polygons
  27. var transPoly:Vector.<Number> = new Vector.<Number>();
  28.  
  29. var i:int;
  30. var inc:int = 0;
  31. for (i = 0; i<polyNum; i++){
  32.     m.identity();
  33.     var s:Number = (int(Math.random()*50) == 1) ? 4 + Math.random()*2 : 1 + Math.random() * 2;
  34.     m.appendScale(s, s, 1);
  35.     m.appendRotation(Math.random()*360, Vector3D.X_AXIS);
  36.     m.appendRotation(Math.random()*360, Vector3D.Y_AXIS);
  37.     m.appendRotation(Math.random()*360, Vector3D.Z_AXIS);
  38.     m.appendTranslation(200,0,0);
  39.                          
  40.     m.appendRotation(Math.random()*360, Vector3D.X_AXIS);
  41.     m.appendRotation(Math.random()*360, Vector3D.Y_AXIS);
  42.     m.appendRotation(Math.random()*360, Vector3D.Z_AXIS);
  43.    
  44.     m.transformVectors(poly, transPoly);
  45.    
  46.     verts = verts.concat(transPoly);
  47.     faces.push(new Vector3D());
  48.     indices.push(inc++, inc++, inc++);
  49.     uvts.push(Math.random(), Math.random(), 0, Math.random(), Math.random(), 0, Math.random(), Math.random(), 0);
  50. }
  51.  
  52. sortedIndices = new Vector.<int>(indices.length, true);
  53.  
  54. // create texture
  55. var tex:BitmapData = new BitmapData(400,400,false, 0x000000);
  56. var grad:Shape = new Shape();
  57. var mat:Matrix = new Matrix();
  58. mat.createGradientBox(400,400,0,0,0);
  59. with (grad.graphics){
  60.     beginGradientFill(GradientType.LINEAR, [0x000000, 0xAA0000, 0xFFFF00], [1, 1, 1], [20, 200, 255], mat);
  61.     drawRect(0,0,400,400);
  62. }
  63. tex.draw(grad);
  64.  
  65. // create background
  66. mat.createGradientBox(1600,1000,0,-550, -100);
  67. with (grad.graphics){
  68.     beginGradientFill(GradientType.RADIAL, [0x333333, 0xffffff], [1, 1], [0, 255], mat);
  69.     drawRect(0,0,500,500);
  70. }
  71. grad.x = -stage.stageWidth/2
  72. grad.y = -stage.stageHeight/2;
  73. addChild(grad);
  74.  
  75. // triangles will be drawn to this
  76. var render:Shape = Shape(addChild(new Shape()));
  77.  
  78. // fix all vector lengths
  79. verts.fixed = true, uvts.fixed = true, indices.fixed = true
  80. pVerts = new Vector.<Number>(verts.length/3 * 2, true);
  81.  
  82. // we need these if we want perspective
  83. var persp:PerspectiveProjection = new PerspectiveProjection();
  84. persp.fieldOfView = 45;
  85. // projection matrix
  86. var proj:Matrix3D = persp.toMatrix3D();
  87.  
  88. var dx:Number = 0, dy:Number = 0;
  89. addEventListener(Event.ENTER_FRAME, onLoop);
  90. function onLoop(evt:Event):void {
  91.     dx += (mouseX - dx) / 4;
  92.     dy += (mouseY - dy) / 4;
  93.     m.identity();
  94.     m.appendRotation(dy, Vector3D.X_AXIS);
  95.     m.appendRotation(dx, Vector3D.Y_AXIS);
  96.     // push everything back so its not to close
  97.     m.appendTranslation(0,0,800);
  98.     // append the projection matrix at the end
  99.     m.append(proj);
  100.    
  101.     Utils3D.projectVectors(m, verts, pVerts, uvts);
  102.    
  103.     var face:Vector3D;
  104.     inc = 0;
  105.     for (var i:int = 0; i<indices.length; i+=3){
  106.         face = faces[inc];
  107.         face.x = indices[i];
  108.         // it may look odd, but casting to an int
  109.         // when doing operations inside array sytnax
  110.         // adds a big speed boost
  111.         face.y = indices[int(i + 1)];
  112.         face.z = indices[int(i + 2)];
  113.         var i3:int = i * 3;
  114.         // get the average z position (t value) and store it in the Vector3D w property
  115.         // depending on your model, you may not need to do an average of all 3 values
  116.         face.w = (uvts[int(i3 + 2)] + uvts[int(i3 + 5)] + uvts[int(i3 + 8)]) * 0.333333;
  117.         inc++;
  118.     }
  119.      
  120.     // sort on w, so far this beats all other sorting methods for speed,
  121.     // faster than Vector.sort(), faster than any custom sort method I could find
  122.     faces.sortOn("w", Array.NUMERIC);
  123.  
  124.     // re-order indices so that faces are drawn in the correct order (back to front);
  125.     inc = 0;
  126.     for each (face in faces){
  127.         sortedIndices[inc++] = face.x;
  128.         sortedIndices[inc++] = face.y;
  129.         sortedIndices[inc++] = face.z;
  130.     }
  131.    
  132.     render.graphics.clear();
  133.     render.graphics.beginBitmapFill(tex, null, false, false);
  134.     render.graphics.drawTriangles(pVerts, sortedIndices, uvts, TriangleCulling.NONE);
  135. }

This is a slightly more advanced version of the z-sorting demo from yesterday. Here 3000 polygons are randomly arranged in a sphere formation...


Have a look at the swf...

This entry was posted in 3D, Graphics, Vector, matrix, misc and tagged , , , , . Bookmark the permalink. Post a comment or leave a trackback: Trackback URL.

6 Comments

  1. Terry Paton
    Posted September 1, 2009 at 2:32 am | Permalink

    HOLY COW, you’ve done it again. Impressive looking.

  2. Zevan
    Posted September 1, 2009 at 3:23 am | Permalink

    Thanks Terry

  3. gludion
    Posted September 2, 2009 at 3:25 am | Permalink

    it looks great, but the sphere on wonderfl is very small (I had to right-click/zoom 2x or 3x). Is there a scale problem?
    ps: I’ve flash player 10.0.r12

    Great blog anyway ;)

  4. Zevan
    Posted September 2, 2009 at 1:22 pm | Permalink

    not sure what would cause the sphere to be small, but if you just copy this code into your timeline or copy the code from wonderfl into flex you can see it full size…

  5. fazeaction
    Posted September 3, 2009 at 11:55 am | Permalink

    If you see sphere small try upgrading flash player 10. Some versions are buggy with perspectiveProjection and matrix3D.

  6. tlecoz
    Posted August 27, 2010 at 6:23 am | Permalink

    The results is really nice (like the others we can find on your blog) !
    Thanks for sharing !

    Just one little thing : I don’t understand why you use Array.sort instead of Vector.sort , this post ( http://webr3.org/experiments/flash-10/fast-z-sort/ ) show us that Vector.sort is pretty much faster than Array.sort

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