Brightness Exteension for adv3Lite
Version 1.0 29-Oct-22
Eric Eve *. This extension provides much of the adv3 ligthting levels functionality in a slightly different form for the adv3Lite library.

It adds brightness and opacity properties to the Thing class, as well as a brightnessWithin() method which returns the current brightness within a room or booth (which is taken to be the brightness of its brightest available light source). The opacity property takes effect only on a container that is defined as transparent, in which case the opacity is the loss of brightness for a light source shining in or out of that container.

The extension is set up to mimic the adv3 brightness scale, in that a brightness of 0 equates to darkness, a brightness of 1 is a self-illuminating object (or isVisibleInDark) that doesn't illuminate anything else, a brightness of 2 provides dim light that's sufficient for examining one's environment but not enough to read by, a brightness of 3 is normal light, and a brightness of 4 is an especially bright light, but game code can implement a differnent scale if desired.

There are limitations to the realism of this brightness model, for example it doesn't accumulate the brightness of multiple light sources, and offers only limited handling of light sources in remote locations in the same SenseRegion. Also, apart from imposing a minimum brightness level required for reading and providing the means to model loss of brightness at a distance or through a semi-transparent medium, it has very little impact on game behaviour out of the box; for the most part, it is up to game code to decide what it wants to do with the brightness mechanism provided.