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Calculate Ellipse

/ Published in: ActionScript 3
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  1. /*
  2. 		* This functions returns an array containing 36 points to draw an
  3. 		* ellipse.
  4. 		*
  5. 		* @param x {double} X coordinate
  6. 		* @param y {double} Y coordinate
  7. 		* @param a {double} Semimajor axis
  8. 		* @param b {double} Semiminor axis
  9. 		* @param angle {double} Angle of the ellipse
  10. 		*/
  11.  
  12. 		private function calculateEllipse(x:Number, y:Number, a:Number, b:Number, angle:Number, steps:Number = 36 ):Array 
  13. 		{
  14. 			var points:Array = [];
  15.  
  16. 			// Angle is given by Degree Value
  17. 			var beta:Number = -angle * (Math.PI / 180); //(Math.PI/180) converts Degree Value into Radians
  18. 			var sinbeta:Number = Math.sin(beta);
  19. 			var cosbeta:Number = Math.cos(beta);
  20.  
  21. 			for (var i:Number = 0; i < 360; i += 360 / steps) 
  22. 			{
  23. 				var alpha:Number = i * (Math.PI / 180) ;
  24. 				var sinalpha:Number = Math.sin(alpha);
  25. 				var cosalpha:Number = Math.cos(alpha);
  26.  
  27. 				var X:Number = x + (a * cosalpha * cosbeta - b * sinalpha * sinbeta);
  28. 				var Y:Number = y + (a * cosalpha * sinbeta + b * sinalpha * cosbeta);
  29.  
  30. 				points.push(new Point(X, Y));
  31. 			}
  32.  
  33. 			return points;
  34. 		}

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