Spec: Augmentations

[JSideris]

For the types of games I want to build, it would be very handy if the engine itself provided a way to augment GameObject instances.

Examples

• Picking up a weapon off the ground, and it modifies the HUD, modifies the appearance of the character, appears in an inventory slot, and modifies the attack behavior of the player.
• Getting a powerup in a game that modifies the player's stats.
• Using an equipable item in an RPG.
• Inventory items could be implemented as augmentations.
• Perks and status effects.

Components of Augmentations

There are multiple features of an augmentation that should be considered.

• Maybe the augmentation has a non-augmented state which can exist within the environment.
• The augmentation within the environment may or may not have physics, and probably has a 2D or 3D render.
• The player should be able to interact with the augmentation. This may be invoked by clicking on it, or by having a physical sensor.
• Perhaps an augmentation could be picked up and stored without being installed.
• Upon installing an augmentation, it takes effect, possibly updating the render of the target, animations, and abilities.
• It should be possible to uninstall an augmentation.
• It may be possible to drop an augmentation.
• Dropping augmentations may be an outcome of death.
• All of the above must work in multiplayer games.

Design Solutioning

The above behavior is so broad, that maybe it makes more sense to break it down into multiple things and not have all this behavior handled by one GameObject or decorator. For instance, it becomes complicated when there are multiple rendering modes of the same augmentation. Currently, the @drawable2d decorator only supports a single displayObject, and I don't want to mess around with @drawable2d, which is a core aspect to the canvas 2D plugin.

So let's break it up.

First, the item that sits in the environment waiting to be picked up can be its own GameObject, and doesn't need to be an addon. However, upon interaction, it could create an addon and install it on the robot that interacts with it, before destroying itself.

The addon itself could just be a modifier for a specific type of GameObject that can be stored in an inventory, installed, and uninstalled.

What about modifications to the GUI (inventory slot)? Perhaps the drop pickup could actually contain two addons: one for the player, and one for the player's inventory/status list.

We need to be able to support game servers that don't know anything about DisplayObjects or rendering, but also the ability to modify the renderings. The most obvious approach is for the target's painter to listen for the augmentation in it's target (the augmented GameObject) and then update the painting.

Another crazy option might be to build a client-side-only addon that acts like an addon for the painter of the target object. This addon would also need to be an extension.

That should solve most of the use cases. The last thing worth mentioning here is that there is a dependency tree that gets created, and it will be necessary to make sure augmentations are only added after the object they are augmenting (when loading from disk or from a network source).