Category Archives: Operators

Haskell Inspired zipWith() Function

Actionscript:
  1. initOperators();
  2.  
  3. trace(zipWith("-", [1,2,3], [1,2,3]));
  4. trace(zipWith("+", [1,2,3], [1,2,3]));
  5. trace(zipWith("*", [1,2,3], [1,2,3]));
  6. trace(zipWith("+", [1,1,1,3], [4,5,6,7]));
  7. trace(zipWith("<<", [2, 4], [1,1]));
  8. /*
  9. outputs:
  10.  
  11. 0,0,0
  12. 2,4,6
  13. 1,4,9
  14. 5,6,7,10
  15. 4,8
  16. */
  17.  
  18. function zipWith(op:String, a:Array, b:Array):Array{
  19.     var aLeng:int = a.length;
  20.     var bLeng:int = b.length;
  21.     var leng:Number = (aLeng <bLeng) ? aLeng : bLeng;
  22.     var zipped:Array = [];
  23.    
  24.     if (!this[op])return [];
  25.    
  26.     for (var i:int = 0; i<leng; i++){
  27.         zipped[i]=this[op](a[i], b[i]);
  28.     }
  29.     return zipped;
  30. }
  31.  
  32. function initOperators():void{
  33.     this["+"]=function(a:Number, b:Number):Number{ return a + b };
  34.     this["-"]=function(a:Number, b:Number):Number{ return a - b };
  35.     this["/"]=function(a:Number, b:Number):Number{ return a / b };
  36.     this["*"]=function(a:Number, b:Number):Number{ return a * b };
  37.     this["%"]=function(a:Number, b:Number):Number{ return a % b };
  38.    
  39.     this["&"]=function(a:Number, b:Number):Number{ return a & b };
  40.     this["<<"]=function(a:Number, b:Number):Number{ return a <<b };
  41.     this["|"]=function(a:Number, b:Number):Number{ return a | b };
  42.     this[">>"]=function(a:Number, b:Number):Number{ return a>> b };
  43.     this[">>>"]=function(a:Number, b:Number):Number{ return a>>> b };
  44.     this["^"]=function(a:Number, b:Number):Number{ return a ^ b };
  45. }

This snippet is basically like the haskell zipWith() function. It can combines two arrays into one array given a single function. In this case I defined a bunch of operator functions, but it would work with any kind of function that takes two arguments and returns a value. You could extend this to work with strings and do other strange things I guess.

If you have yet to go play with haskell ... go do it now.

Also posted in Number, arrays, binary, functions, misc, return values | Tagged , , , | 2 Comments

Bitwise OR | and Variable Function Arguments (bitwise flags)

Actionscript:
  1. const A:uint = 1;
  2. const B:uint = 2;
  3. const C:uint = 4;
  4. const D:uint = 8;
  5. const E:uint = 16;
  6.  
  7. function orArgs(args:uint):void{
  8.     if (args & A){
  9.         trace("A");
  10.     }
  11.     if (args & B){
  12.         trace("B");
  13.     }
  14.     if (args & C){
  15.         trace("C");
  16.     }
  17.     if (args & D){
  18.         trace("D");
  19.     }
  20.     if (args & E){
  21.         trace("E");
  22.     }
  23. }
  24.  
  25. // test out the function:
  26. orArgs(A | B);
  27. trace("--");
  28. orArgs(A | C | E);
  29. trace("--");
  30. orArgs(B | E | D);
  31. trace("--");
  32. orArgs(C | A);
  33.  
  34. /* outputs:
  35. A
  36. B
  37. --
  38. A
  39. C
  40. E
  41. --
  42. B
  43. D
  44. E
  45. --
  46. A
  47. C
  48. */

If you've every used Array.sort(Array.NUMERIC | Array.DESCENDING) you should have at least a vague idea about what this snippet is doing. It shows how you can pass a variable number of arguments to a function using | (bitwise OR) and & (bitwise AND). I believe the correct term for these kind of arguments is "bitwise flags". This snippet works by having a series of constant values... in this case A - E. Each constant is assigned an unsigned integer... now you may not see the significance of the values 1, 2, 4, 8 and 16 until you see them in binary... get ready this is a pretty cryptic description...

A = 00001 = 1
B = 00010 = 2
C = 00100 = 4
D = 01000 = 8
E = 10000 = 16

If we OR all these together we get: 11111... If we do:

A | E
00001 | 10000

we end up with 10001...

...we can then check which values are stored in the resulting unsigned integer by using AND:

check for A... 10001 & 00001 = 00001 = true
check for E... 10001 & 10000 = 10000 = true
check for C... 10001 & 00100 = 00000 = false

That's it... I just guessed at the way this was being done... if you have another way to do the same thing, feel free to post it in the comments....

Also posted in Math, binary, misc | Tagged , , , | 1 Comment

Sierpiński Glitch Texture #3

Actionscript:
  1. [SWF(frameRate=60, backgroundColor=0x000000, width=500, height=500)]
  2.  
  3. var canvas:BitmapData = new BitmapData(500,500,false, 0x000000);
  4. addChild(new Bitmap(canvas));
  5. var clone:BitmapData = new BitmapData(500,500,false, 0x000000);
  6. var canvasRect:Rectangle = canvas.rect;
  7. var w:int = canvas.width;
  8. var w2:Number = 1/w;
  9. var w10:Number = 1/(w * 80);
  10. var convert:Number = Math.PI/180;
  11. var size:int = canvas.width * canvas.height;
  12. var pix:Vector.<uint> = new Vector.<uint>(size, true);
  13. var m:Matrix = new Matrix();
  14. m.scale(1,-1);
  15. m.translate(0,canvas.height);
  16. var sin:Number = 0, cos:Number = 0;
  17. var dx:Number = 0, dy:Number = 0;
  18. var pnt:Point = new Point();
  19. var blur:BlurFilter = new BlurFilter(10,10,1);
  20. addEventListener(Event.ENTER_FRAME, onLoop);
  21. function onLoop(evt:Event):void {
  22.     canvas.lock();
  23.     dx +=  (mouseX * 10 - 3000 - dx) / 8;
  24.     dy +=  (mouseY * 4 - dy) / 8;
  25.     for (var i:int = 0; i<size; i++){
  26.         var xp:int = i % w;
  27.         var yp:int = int(i * w2);
  28.         var xp2:int = xp <<1;
  29.         var t:Number;
  30.         t = ((yp|(xp + yp * 0.1)) * (xp + dx) *w10) % 6.14687;
  31.         //compute sine
  32.         // technique from http://lab.polygonal.de/2007/07/18/fast-and-accurate-sinecosine-approximation/
  33.         // by Michael Baczynski
  34.         if (t<0) {
  35.             sin=1.27323954*t+.405284735*t*t;
  36.         } else {
  37.             sin=1.27323954*t-0.405284735*t*t;
  38.         }
  39.         // compute cosine
  40.         t = (xp2|(yp+xp*0.1) + dy) * convert % 6.28;
  41.         t+=1.57079632;
  42.         if (t>3.14159265) {
  43.             t-=6.28318531;
  44.         }
  45.         if (t<0) {
  46.             cos=1.27323954*t+0.405284735*t*t;
  47.         } else {
  48.             cos=1.27323954*t-0.405284735*t*t;
  49.         }
  50.         var c1:int = 31 * (sin - cos);
  51.         if (c1 <0) c1 = 256 - c1;
  52.         c1 = (c1 <<4 | c1) ;
  53.         pix[i] = c1 <<16 | c1 <<8 | c1;
  54.     }
  55.     canvas.setVector(canvasRect, pix);
  56.     clone.copyPixels(canvas, canvasRect, pnt);
  57.     canvas.draw(clone, m, null, BlendMode.SUBTRACT);
  58.     clone.copyPixels(canvas, canvasRect, pnt);
  59.     clone.applyFilter(clone, canvasRect, pnt, blur);
  60.     canvas.draw(clone, null, null, BlendMode.SCREEN);
  61.     canvas.unlock();
  62. }

Decided to do a grayscale version ... also rendered it out large and posted it on flickr...

Check out the swf...


Check out the large flickr version...

Also posted in BitmapData, Vector, pixel manipulation | Tagged , , | 2 Comments

Sierpiński Glitch Texture #2

Actionscript:
  1. [SWF(frameRate=60, backgroundColor=0x000000, width=500, height=500)]
  2. var canvas:BitmapData = new BitmapData(500,500,false, 0x000000);
  3. addChild(new Bitmap(canvas));
  4. var clone:BitmapData = new BitmapData(500,500,false, 0x000000);
  5. var canvasRect:Rectangle = canvas.rect;
  6. var w:int = canvas.width;
  7. var w2:Number = 1/w;
  8. var w10:Number = 1/(w * 80);
  9. var convert:Number = Math.PI/180;
  10. var size:int = canvas.width * canvas.height;
  11. var pix:Vector.<uint> = new Vector.<uint>(size, true);
  12. var gray:ColorMatrixFilter = new ColorMatrixFilter([1, 0.55, 0.55, 0,0,0.55, 0.9, 0.55, 0,0,0.55, 0.55, 0.550,0, 0,0,0,1,0]);
  13. var m:Matrix = new Matrix();
  14. m.scale(1,-1);
  15. m.translate(0,canvas.height);
  16. var sin:Number = 0, cos:Number = 0;
  17. var dx:Number = 0, dy:Number = 0;
  18. var pnt:Point = new Point();
  19. var blur:BlurFilter = new BlurFilter(10,10,1);
  20. addEventListener(Event.ENTER_FRAME, onLoop);
  21. function onLoop(evt:Event):void {
  22.     canvas.lock();
  23.     dx += (mouseX * 10 - 3000 - dx) / 8;
  24.     dy += (mouseY * 4 - dy) / 8;
  25.     for (var i:int = 0; i<size; i++){
  26.         var xp:int = i % w;
  27.         var yp:int = int(i * w2);
  28.         var xp2:int = xp <<1;
  29.         var t:Number;
  30.         t = ((yp|(xp + yp)) * (xp + dx) *w10) % 6.14687;
  31.         //compute sine
  32.         // technique from http://lab.polygonal.de/2007/07/18/fast-and-accurate-sinecosine-approximation/
  33.         // by Michael Baczynski
  34.         if (t<0) {
  35.             sin=1.27323954*t+.405284735*t*t;
  36.         } else {
  37.             sin=1.27323954*t-0.405284735*t*t;
  38.         }
  39.         // compute cosine
  40.         t = (xp2|(yp+xp/dx) + dy) * convert % 6.28;
  41.         t+=1.57079632;
  42.         if (t>3.14159265) {
  43.             t-=6.28318531;
  44.         }
  45.         if (t<0) {
  46.             cos=1.27323954*t+0.405284735*t*t;
  47.         } else {
  48.             cos=1.27323954*t-0.405284735*t*t;
  49.         }
  50.         var c1:int = 31 * (sin - cos);
  51.         if (c1 <0) c1 = 256 - c1;
  52.         c1 = (c1>>1  | c1) ;
  53.         pix[i] = c1 <<17 | c1 <<8 | c1;
  54.     }
  55.     canvas.setVector(canvasRect, pix);
  56.     clone.copyPixels(canvas, canvasRect, pnt);
  57.     canvas.draw(clone, m, null, BlendMode.SUBTRACT);
  58.     clone.copyPixels(canvas, canvasRect, pnt);
  59.     clone.applyFilter(clone, canvasRect, pnt, blur);
  60.    
  61.     canvas.draw(clone, null, null, BlendMode.LIGHTEN);
  62.     canvas.applyFilter(canvas, canvasRect, pnt, gray);
  63.     canvas.unlock();
  64. }

More texture experimentation...

Have a look at the swf over at wonderfl.net...

Also posted in BitmapData, Vector, pixel manipulation | Tagged , , | Leave a comment