AS3-Vector2D

A lean Vector2D tool for AS3 projects that supports inlining.

The following operations can be applied (and more):

to/from radians
normalising
projection
length/magnitude
left/right vectors
dot/scalar
reflection
parallel testing
orthogonal testing
sign between two vectors

Design Choices

To make AS3-Vector2D fast and efficient, the vector operations are applied as static inline'd functions against a Point2D data structure.

This will allow you to use Point2D very efficiently while keeping the vector operations clean and simple.

You will notice some of the operations have an "out" function argument...

function project(v1:Point2D, normal:Point2D, out:Point2D)

...This is because AS3-Vector2D is cache friendly and allows developers to re-use Point2D instances to speed up performance as shown in the examples below!

How to use

A general work flow would be to:

Create Point2D instances to store the x and y components
Use the Vector2D tool to perform operations on the Point2D instances

Scenario

A scenario where you want the player to move towards an enemy at a fixed speed until the player touches the enemy...

The output from both examples will be:

Point2D:{x:100, y:200}

Point2D:{x:150, y:200}

Point2D:{x:200, y:200}

Example 1 - without caching

		//Mock objects representing the player and enemy data...
		var p:Object = {x: 100, y: 200, vx: 0, vy: 0, speed: 50, radius: 10};
		var e:Object = {x: 200, y: 200, vx: 0, vy: 0, radius: 10};
		
		var playerPos:Point2D = new Point2D(p.x, p.y);
		var enemyPos:Point2D = new Point2D(e.x, e.y);
		
		var distance:Number = Number.MAX_VALUE;
		
		
		while (true)
		{
			trace(playerPos); 
			
			var delta:Point2D = Point2D.sub(enemyPos, playerPos, new Point2D());
			
			distance = Vector2D.findLength(delta);
			
			if (distance > p.radius + e.radius)
			{
				var impluse:Point2D = Point2D.scale(Vector2D.normalise(delta, new Point2D()), p.speed);
				playerPos.x += impluse.x;
				playerPos.y += impluse.y;
				
			}else
			{
				break;
			}
		}
		
		p.x = playerPos.x;
		p.y = playerPos.y;

Example 2 - with caching

		//Mock objects representing the player and enemy data...
		var p:Object = {x: 100, y: 200, vx: 0, vy: 0, speed: 50, radius: 10};
		var e:Object = {x: 200, y: 200, vx: 0, vy: 0, radius: 10};
		
		var playerPos:Point2D = new Point2D(p.x, p.y);
		var enemyPos:Point2D = new Point2D(e.x, e.y);
		
		var distance:Number = Number.MAX_VALUE;
		var cache:Point2D = new Point2D();
		
		
		while (true)
		{
			trace(playerPos);
			
			var delta:Point2D = Point2D.sub(enemyPos, playerPos, cache);
			
			distance = Vector2D.findLength(delta);
			
			if (distance > p.radius + e.radius)
			{
				var impluse:Point2D = Point2D.scale(Vector2D.normalise(delta, cache), p.speed);
				playerPos.x += impluse.x;
				playerPos.y += impluse.y;
				
			}else
			{
				break;
			}
		}
		
		p.x = playerPos.x;
		p.y = playerPos.y;

This version saves many creations of Point2D instantiation by using and writing/reading to a cached point.