Parapluie

A simple, build- and dependency-free JavaScript engine

Variables

Variable	Description
roomWidth	Room size (not canvas size)
roomHeight	Room size (not canvas size)
canvasWidth	TODO replace with canvas.width?
canvasHeight	TODO replace with canvas.height?
room	Stores active room

Room

All rooms extend the Room class. Stores list of objects objects and creates objects.

Each room can optionally be initialized with a returnRoom (use Game.gotoRoom). When Room.return is called it will return to this room.

step() and draw()

In each interval first step() and then draw() from the room is called. In the superclass Room the list of objects objects is traversed and step() or resp. draw() of each object is called.

Each room and each object should always call super.step() or super.draw() if they override one of these methods.

The step() method is used for non-visible functional changes and the draw() method then draws on the canvas.

Entities

Coordinates

Each GameEntity has coordinates x and y which define the x and y value on the in the room. When the canvas is scaled to a different size, these values do not match the coordinates on the canvas any more. Use variables xScalar and yScalar to scale internal distances and xD and yD for coordinates mapped to the screen.

Variable	Description
x	x-coordinate in the room
y	y-coordinate in the room
width	Entity-width in room
height	Entity-heigh in room
ox	Origin-variable (Usually when a sprite is drawn at point (x,y) top-left corner will be at this coordinate, this describes the offset)
oy	Origin-variable

Entity types

• GameEntity (Most basic class that can be added to the game loop, has step and draw)
• PhysicalEntity (Extends GameEntity, has coordinates, dimension, collision, speeds, direction)
• SpriteEntity (Extends PhysicalEntity, has Sprite)