panda3d-keybindings

Panda3D comes with a nice API suite to work with input devices. In particular, it has one for USB HIDs, and one for mouse and keyboard. What it does not have is a mechanism to build an abstraction over these devices, so that a developer can define them in terms of a set of buttons and axes, and it is a matter of configuration how actual inputs on devices are mapped to those abstract inputs. A game's logic should not be concerned with details like...

whether a 2D axis gets its values from a gamepad's stick or its four buttons, from WASD, or a dance pad.
how the player wants the inputs from the devices combined. There may be a different list of priorities for different abstract inputs with regard what devices should be checked. A player may prefer to cotrol character movement on a gamepad, but functions like invoking and working in menus with the keyboard.
how input is preprocessed. Badly manufactured sticks create noise near the center, and may require a dead zone. An axis' amplitude may need to be scaled or squared.
devices connecting or disconnecting. From a game developer's perspective, these events should be dealt with under the hood.
how devices are identified. A player may use two flight sticks for a space simulator. If they're of different makes, they can be identified "uniquely", and should be mappable independent of one another. Even with two identical sticks, there should be a way to check which is which ("Press trigger on left stick"), and label them accordingly. NOTE: Not implemented yes.
providing an interface to work with the mappings. NOTE: Completely inexistent so far.
if the state, when polled at different times during a frame, is still the same; It just should be. This is quite an edge case, but may cause hard to reproduce bugs. NOTE: Currently only very partially implemented, but the difference between that and the current version is, after all, only relevant for that edge case.

Status

This project's state is alpha. The polling interface works quite well and is feature-rich. The major missing features for beta are throwing Panda3D events, and freezing the state for a frame.

Installation

pip install panda3d-keybindings

Concepts

A virtual input a button or axis (or other) with a semantic to the game. It has
- a type, which is one of
  - button: True if the button is pressed, False otherwise.
  - trigger: True for the frame in which the button is pressed.
  - axis: A float.
  - axis2d: panda3d.core.Vec2.
  - axis3d: panda3d.core.Vec3.
- a device order, stating the highest priority to the lowest to check for presence and state when reading a context.
- a sensor definition for each usable device. This defines the buttons / axes used, and specifies post-processing that is to be done on them.
A context is a set of virtual inputs that is read together. It is an organizational unit to make it easy for the application to activate or deactivate parts of the user input interface. For example, opening the game's ingame menu may activate the menu context, and deactivate the character_movement one.
When a device is connected, it is assigned to a player, or kept unassigned for the time being. Players will only be able to read data from devices assigned to them. NOTE: Currently only single-player assigners exist off-the-shelf.
There's a TOML file that defines for each player and each context in what order to check devices for a virtual input. If the first enumerated device isn't assigned to the player, the next one will be checked, and so on, until one is found that can be read. NOTE: Currently no concept of players exists in the config file.
- Each entry should contain filterable data like device type, device ID, etc. NOTE: Utterly unimplemented.

Example

Setting up an application for use with this module is easy:

from direct.showbase.ShowBase import ShowBase
from keybindings.device_listener import add_device_listener
from keybindings.device_listener import SinglePlayerAssigner

ShowBase()
add_device_listener(
    config_file='keybindings.toml',
    assigner=SinglePlayerAssigner(),
)

Now there is a base.device_listener.

A keybinding configuration could look like this:

[demo_context]

  [demo_context.demo_button]
  _type = "button"
  _device_order = ["gamepad", "flight_stick", "keyboard"]
  gamepad = "face_a"
  flight_stick = "trigger"
  keyboard = "q"

When the context demo_context is read, ...

base.device_listener.read_context('demo_context')

...the result may look like this:

{'demo_button': False}

This means that due to the config snippet above, the device listener has checked whether a gamepad is connected; If so, the state of face_a is used, if not, the flight_stick is tested next, and so on. In this example, a device has been found and the button has not been pressed.

If no device type is found to be connected, the returned state would be None. Do note that if a keyboard is listed as a possible option, it will be assumed to be present.

TODO