July 6th, 2010 
Ntt.cc 
We have listed 12 very simple,basic but useful function source in Flex in the previous article. The mathematical calculation will be used regularly in our Flash/Flex applications, we can easily find the open source libraries like 30+ useful as3 open source projects, but it’s superfluous when we only need calculate the distance between two points, or only want to get the circle area. Here is the list of 16 useful AS3 arithmetic & formulas. Have any proudly and recommendable? Leave your comments to share please.
1. Distance Between Two Points
- dx = x2 – x1;
- dy = y2 – y1;
- dist = Math.sqrt(dx*dx + dy*dy);
2. Inching Formulas
- sprite.x += (targetX - sprite.x) * easing;//easing: inching coefficient
- sprite.y += (targetY - sprite.y) * easing;
3. Elastic Formulas
- vx += (targetX - sprite.x) * spring; //spring: elastic coefficient
- vy += (targetY - sprite.y) * spring;
- sprite.x += (vx *= friction); //friction: friction force
- sprite.y += (vy *= friction);
4. Flexible Partial Shifts Formulas
- var dx:Number = sprite.x - fixedX;
- var dy:Number = sprite.y - fixedY;
- var angle:Number = Math.atan2(dy, dx);
- var targetX:Number = fixedX + Math.cos(angle) * springLength;
- var targetY:Number = fixedX + Math.sin(angle) * springLength;
5. Rotation With Mouse Formulas
- dx = mouseX - sprite.x;
- dy = mouseY - sprite.y;
- sprite.rotation = Math.atan2(dy, dx) * 180 / Math.PI;
6. Waveform Formulas
- public function onEnterFrame1(event:Event):void {
- ball.y=centerScale+Math.sin(angle)*range;
- angle+=speed;
- }
7. Heartthrob Formulas
- public function onEnterFrame1(event:Event):void {
- ball.scaleX=centerScale+Math.sin(angle)*range;
- ball.scaleY=centerScale+Math.sin(angle)*range;
- angle+=speed;
- }
8. Circle Rotation Formulas
- public function onEnterFrame(event:Event):void {
- ball.x=centerX+Math.cos(angle)*radius;
- ball.y=centerY+Math.sin(angle)*radius;
- angle+=speed;
- }
9. Get Circle Area
- public function getArea():Number
- {
- // The formula is Pi times the radius squared.
- return Math.PI * Math.pow((width / 2), 2);
- }
10. Get Circumference Ratio
- public function getCircumference():Number
- {
- // The formula is Pi times the diameter.
- return Math.PI * width;
- }
11. Elliptic Rotation Formulas
- public function onEnterFrame(event:Event):void {
- ball.x=centerX+Math.cos(angle)*radiusX;
- ball.y=centerY+Math.sin(angle)*radiusY;
- angle+=speed;
- }
12. Color operations
- var t:uint=0×77ff8877
- var s:uint=0xff000000
- var h:uint=t&s
- var m:uint=h>>>24
- trace(m);
13. Hex to Decimal
- trace(hexValue);
14. Decimal to Hex
- decimalValue.toString(16);
15. Pick Up Color
- red = color24 >> 16;
- green = color24 >> 8 & 0xFF;
- blue = color24 & 0xFF;
- alpha = color32 >> 24;
- red = color32 >> 16 & 0xFF;
- green = color32 >> 8 & 0xFF;
- blue = color232 & 0xFF;
16. Color Bit Arithmetic
- color24 = red << 16 | green << 8 | blue;
- color32 = alpha << 24 | red << 16 | green << 8 | blue;
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some of them are very useful for me.
thanks
[...] 16 Useful Mathematical Formulas In ActionScript 3 Enjoy! [...]
Hi, nice overview! What does ‘Color operations’ (12.) exactly traces?
I think the source:
var h:uint=t&s
var m:uint=h>>>24
should be the crux, the line of trace was only the test source code.
right?
I would add this:
Rotating a 2D Vector:
http://snipt.org/TSi
Real difference between two angles:
http://snipt.org/TSj
I’ll post if I think of something else..
Cheers
szataniol
WOW!!! Rotate 2D Vector function!
public function rotate(angle : Number) : void {
var sin : Number = Math.sin(angle);
var cos : Number = Math.cos(angle);
var oldX : Number = x;
var oldY : Number = y;
x = oldX * cos – oldY * sin;
y = oldX * sin + oldY * cos;
}
It’s helpful for me! Thank you!!!
Getting control to draw curve through a point:
http://snipt.org/TXp
This one is very useful if you want to draw a bezier curve THROUGH that point, not using is as a control point.
Great!
Many thanks, szataniol.
I’m not sure if this is related with the topic, anyway here’s some simple mouse avoiding:
http://blog.szataniol.pl/?p=60
cheers
szataniol