u

This object contains a number of handy utility functions to ease the development process.

Geometry

u.ldx(length, direction) and u.lengthDirX(length, direction)

Gets the horizontal part of a vector.

Example: Spawn a bullet relative to the hero sprite

JavaScript

var dx = u.ldx(40, this.angle),
    dy = u.ldy(40, this.angle);
var bullet = templates.copy('Bullet', this + dx, this + dy);
bullet.direction = this.angle;

CoffeeScript

dx = u.ldx 40, @angle
dy = u.ldy 40, @angle
bullet = templates.copy 'Bullet', this + dx, this + dy
bullet.direction = @angle

Catnip

Set dx value x length of a vector texture rotationSet dy value y length of a vector texture rotationCopy a template Star x + dx y + dy

store in projectile

Advanced

Write projectile property value texture rotation

u.ldy(length, direction) and u.lengthDirY(length, direction)

Gets the vertical part of a vector.

u.distance(from, to)

Returns the distance from one object to another. The objects must have x and y coordinates. (Copies do have them.)

Example: Get the distance between the current copy and the player's character

JavaScript

var player = templates.list['Hero'][0];
if (templates.valid(player)) {
    console.log(u.distance(this, player));
}

CoffeeScript

player = templates.list['Hero'][0]
if templates.valid player
    console.log u.distance(this, player)

Catnip

Set player value get array element templates list Hero at If is valid player

Log to console distance between this player

u.direction(from, to)

Returns the direction of a vector that goes from one object to another, in degrees. The objects must have x and y coordinates. (Copies do have them.)

Example: Get the direction from the current copy to the player's character and shoot a projectile

JavaScript

var player = templates.list['Hero'][0];
if (templates.valid(player)) {
    var projectile = templates.copy('Laser', this.x, this.y);
    projectile.direction = u.direction(this, player);
}

CoffeeScript

player = templates.list['Hero'][0]
if templates.valid player
    projectile = templates.copy 'Laser', @x, @y
    projectile.direction = u.direction this, player

Catnip

Set player value get array element templates list PotatoCat at If is valid player

Copy a template Laser x y

store in projectile

Advanced

With copy projectile

Set direction to direction this player

u.pdn(x1, y1, x2, y2) and u.pointDirection(x1, y1, x2, y2)

Gets the direction of vector which is pointing from (x1;y1) to (x2;y2).

u.pdc(x1, y1, x2, y2) and u.pointDistance(x1, y1, x2, y2)

Gets the distance between points (x1;y1) and (x2;y2).

u.rotate(x, y, deg)

Rotates a given vector by a given angle. Returns an object (PIXI.Point) with two properties: x and y components.

u.rotateRad(x, y, rad)

The same as u.rotate, but the angle is given in radians. Returns an object (PIXI.Point) with two properties: x and y components.

u.degToRad(deg)

Converts degrees into radians.

u.radToDeg(rad)

Converts radians into degrees.

u.deltaDir(dir1, dir2)

Returns a difference between two directions, in degrees.

Gameplay and UI Coordinates

u.uiToGameCoord(x, y)

Converts from UI coordinates to game coordinates. Returns an object (PIXI.Point) with two properties: x and y components.

u.gameToUiCoord(x, y)

Converts from game coordinates to ui coordinates. Returns an object (PIXI.Point) with two properties: x and y components.

Math

u.clamp(min, val, max)

Returns a clamped value val.

u.lerp(a, b, alpha)

Linearly interpolates a value from a to b, returning a if alpha = 0 and b if alpha = 1.

u.unlerp(a, b, val)

An opposite of u.lerp. Returns a position of val inside a range from a to b. If val is inside this range, this method will return a value between 0 and 1.

u.map(val, inMin, inMax, outMin, outMax)

Re-maps the given val from one number range (inMin - inMax) to another (outMin - outMax).

Built-in collision checks

u.prect(x1, y1, arg: Array|Copy) and u.pointRectangle(x1, y1, arg: Array|Copy)

Checks if a given point (x1;y1) is inside a rectangle. arg can be either an array of coordinates ([x1, y1, x2, y2]) or a Copy with a rectangular shape.

u.pcircle(x1, y1, arg: Array|Copy) and u.pointCircle(x1, y1, arg: Array|Copy)

Checks if a given point is inside a circle. arg can be either an array of [x1, y1, radius], or a Copy with a cirular shape.

Time values

u.time

A measure of how long the previous frame took time to draw, in seconds.
You can use it by multiplying it with your copies' speed and other values with velocity to get the same speed with different framerate, regardless of lags or max framerate cap.

If you plan on changing your game's target framerate, you should use u.time instead of u.delta.

A minimal example:

this.x += this.windSpeed * u.time;

Note that this.move() already uses this value, so there is no need to premultiply this.speed with it.

u.timeUi

Similarly to u.time, this property also measures the time between the previous and current frames, in seconds, but this value ignores the effects of slow-mo and game pause. (See about pausing the game and changing game speed here.)

u.delta

A measure of how long the previous frame took time to draw, usually equal to 1 and larger on lags.
For example, if it is equal to 2, it means that the previous frame took twice as much time compared to expected FPS rate.

This is a deprecated property.

Use u.time instead.

u.deltaUi

Similar to u.delta, this property also measures the time between the previous and current frames, but this value ignores the effects of slow-mo and game pause. (See about pausing the game and changing game speed here.)

This is a deprecated property.

Use u.timeUi instead.

Miscellaneous

u.hexToPixi(hex: string)

Converts a hex string to a Pixi color.

Example: Set copy's tint color from a CSS color

JavaScript

this.tint = u.hexToPixi('#0dfac3');

CoffeeScript

@tint = u.hexToPixi '#0dfac3'

u.pixiToHex(pixi: number)

Converts a Pixi color to a hex-encoded color code.

Example: Set page's background color from a Pixi color

JavaScript

document.body.style.backgroundColor = u.pixiToHex(0x0dfac3);

CoffeeScript

document.body.style.backgroundColor = u.pixiToHex 0x0dfac3

u.wait(time)

Returns a Promise. Waits time milliseconds, then resolves without any data. Rejects if a new room was loaded before the Promise was resolved. Example:

JavaScript

var enemy = whatever;
enemy.state = 'Disappear';
u.wait(1000)
.then(() => {
    if (!enemy.kill) { // this will happen a second after the code above was called.
        enemy.kill = true;
    }
});

CoffeeScript

enemy = whatever
enemy.state = 'Disappear'
u.wait 1000
.then =>
    if not enemy.kill
        # this will happen a second after the code above was called.
        enemy.kill = yes

u.load(url: String, callback: Function)

Loads the specified script and calls the callback when it was loaded.