COLLISIONS BETWEEN CIRCLES in Font
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Matrix 2D Barcode Encoder In Visual C#.NET Using Barcode drawer for VS .NET Control to generate, create Matrix 2D Barcode image in VS .NET applications. www.OnBarcode.comPaint Barcode In Java Using Barcode creator for Java Control to generate, create Barcode image in Java applications. www.OnBarcode.comto know this information so that we can correctly add or subtract the overlap vector to each circle s position. The easiest way to track this is by creating variables that are assigned 1 or 1, depending on where the circles are in relation to each other. Why we need to do this will become clear in the next step. var xSide:int; var ySide:int; _c1.xPos > _c2.xPos xSide = 1 : xSide = 1; _c1.yPos > _c2.yPos ySide = 1 : ySide = 1; This bit of code illustrates the use of the ternary operation. It s a shorthand style of writing if / else statements. This line of code _c1.xPos > _c2.xPos xSide = 1 : xSide = 1; is the same as writing this: if(_c1.xPos > _c2.xPos) { xSide = 1; } else { xSide = 1; } For short, simple conditional tests, the ternary operation is very helpful. It takes up much less space and will make your code more readable once your eyes get used to the syntax. Try it! 4. We need to push the circles apart to resolve the collision. For example, on the x axis, we ll need to push one circle to the left and the other to the right. The collision vector that we calculated in step 2 will be the correct direction for one of the circles, but not the other. However, we know that the directions the circles need to move in will be the polar opposites of each other. That means we can use the xSide and ySide variables (which will be 1 or 1) to correctly invert one of the vectors. //Move _c1 out of the collision _c1.setX = _c1.xPos + (collision_Vx * xSide); _c1.setY = _c1.yPos + (collision_Vy * ySide); //Move _c2 out of the collision _c2.setX = _c2.xPos + (collision_Vx * xSide); _c2.setY = _c2.yPos + (collision_Vy * ySide); The orientation of the circles will always be changing, so we can never know which circle s overlap vector to invert. Luckily, the xSide and ySide variables take care of keeping track of that for us automatically. Figure 323 shows how the circles new positions are found.

