shade

A lighting/shadow engine for the ImpactJS game engine

Features

• Standalone. Doesn't depend on Impact++ or other large libraries.
• Simple. Lights are just ImpactJS Entitys, and can be created and manipulated the same way you would do for any other Entity. Shadow-casting lights integrate seamlessly with CollisionMap so that collision tiles of any shape cast shadows.
• Configurable. Change the color, smoothness, and gradient of your lights. Whether or not lights cast shadows can also be configured.
• Extensible. Though the library currenly only implements point lights, it's simple to implement other types of lights.
• Dynamic. Moving lights, moving objects, and moving shadows.

Installation

• Copy the shade source (the folder containing "main.js") into a folder called "shade" in your ImpactJS project's "lib/plugins" folder.
• Register the plugin in your own "main.js" file:

.requires(
    'plugins.shade.main'
)

• Create sh.Light entities in your game. You can do this programmatically by requireing 'plugins.shade.light' and calling ig.game.spawnEntity(sh.Light, x, y, settings). Alternatively, you can add it to a map using Weltmeister. The easiest way to expose sh.Light to Weltmeister is to create a simple subclass in your "lib/game/entities" folder:

ig.module(
    'game.entities.light'
).requires(
    'plugins.shade.light'
).defines(function () {

    EntityLight = sh.Light.extend({ });

});

Usage

shade sh.Lights are created just like any other Entity in ImpactJS. To configure an sh.Light, simply pass in settings via Game.spawnEntity or via Weltmeister. sh.Light supports the following options:

• size The size of the light.
• gradient Set to true to indicate that this light should have a gradient.
• color A color object of the form { r, g, b }. Changing this at any time after the Light has already been initialized will immediately update the Light.
• smooth Set this to false to get a "retro"/pixelated look proportional to ig.game.scale.
• shadows Set this to false to prevent this light from creating shadows when objects are in its way. Not casting shadows is better for performance.

In addition to Light, there is also a global sh.LightManager. The only really interesting thing about the light manager is that you can change the global ambient light by modifying the color property on the global sh.lightManager.

One new property has been added to ig.Entity's prototype as well: the opaque property. When set to false, the given Entity will not cast shadows. When set to true a shadow will be cast by the given Entity's bounding rectangle (as determined by its position and size). This property can also be set to an Array of { x, y } points defining a concave polygon to be used for shadow casting instead of its bounding rectangle.