Vector

Vectors

Excalibur uses the Vector structure to represent points. The Vector class has many different static methods available for doing vector math as well as instance methods to combine vectors together in different ways.

Creating vectors

To quickly create a vector, use the vec global:

ts
import { vec } from 'excalibur'
const point = vec(0, 10)

ts
import { vec } from 'excalibur'
const point = vec(0, 10)

Alternatively, you may see examples of using the more verbose new Vector(x, y) format:

ts
import { Vector } from 'excalibur'
const point = new Vector(0, 10)

ts
import { Vector } from 'excalibur'
const point = new Vector(0, 10)

To set the value of an existing vector, use Vector.setTo:

ts
import { vec } from 'excalibur'
const point = vec(0, 10).setTo(10, 10)

ts
import { vec } from 'excalibur'
const point = vec(0, 10).setTo(10, 10)

There are some built-in vector constants you can use:

• Vector.Zero
• Vector.One
• Vector.Half
• Vector.Left
• Vector.Right
• Vector.Up
• Vector.Down

Cloning vectors

Vectors are objects, so mutating them will change the state for all references. Use the Vector.clone method to clone a vector to mutate it:

ts
import { vec } from 'excalibur'
const point = vec(0, 10)
const samePoint = point.setTo(8, 8)
const anotherPoint = point.clone().setTo(50, 50)
console.log(point.toString()) // "(8, 8)"
console.log(samePoint.toString()) // "(8, 8)"
console.log(anotherPoint.toString()) // "(50, 50)"

ts
import { vec } from 'excalibur'
const point = vec(0, 10)
const samePoint = point.setTo(8, 8)
const anotherPoint = point.clone().setTo(50, 50)
console.log(point.toString()) // "(8, 8)"
console.log(samePoint.toString()) // "(8, 8)"
console.log(anotherPoint.toString()) // "(50, 50)"

Notice how both point and samePoint share the same vector reference, so using setTo mutates the vector. Use clone to ensure you are not changing vectors unexpectedly!