Last updated by: Оргил-Эрдэнэ, Last updated on: 16/05/2025

Unity Bike Movement System

Script Name	Responsibility
PlayerController	Entry point that assigns input and movement handlers to the active bike
IBikeMover	Interface to abstract bike movement logic
IPlayerInput	Interface to abstract input source (Axis, XR, MQTT)
SimpleBikeController	Arcade-style simplified bike movement
RealisticBikeController	Physics-based realistic bike movement and balance
AxisInput	Uses Unity Input (keyboard/controller)
MQTTInput	Uses MQTT topics to get steering and speed
XRInput	Uses XR controller joystick axis for input

PlayerController

• Selects and initializes the appropriate movement controller (IBikeMover)

• Dynamically chooses the input handler (IPlayerInput) based on:

  • MQTT connection
  • XR controller detection
  • Fallback to keyboard

• Passes input values to the active IBikeMover in FixedUpdate()

• Handles score collection through OnTriggerEnter

• Exposes SetSpeed() and GetSpeed() for runtime tuning

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IBikeMover Interface

Defines the API for movement components:

float Speed { get; set; }
void Init(GameObject controller);
void HanldeInput(Vector2 direction);

IPlayerInput Interface

Defines how directional input is gathered. All implementations return a Vector2:

• x: Horizontal steering
• y: Forward/backward movement

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SimpleBikeController

Arcade-style bike movement:

• No physics (rigidbody is kinematic)
• Manual rotation and translation based on direction
• Rotates wheels visually
• Aligns bike to terrain normal for realism

Best for: simple mobile control, joystick or keyboard input.

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RealisticBikeController

Physics-based bike system:

• Controls motor torque, braking, and steering via WheelColliders
• Computes steering angle reduction at higher speeds
• Uses AnimationCurve to simulate self-balancing (torque applied against tilt)
• Leaning is computed and visualized
• Syncs visual wheel rotation with physics colliders

Best for: immersive VR, realistic terrain, and learning physics principles.

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AxisInput

• Uses Unity's built-in Input.GetAxis("Horizontal"/"Vertical")
• Best for development/testing or traditional control schemes

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MQTTInput

• Subscribes to MQTT topics for:

  • Speed control
  • Left/right turns

• Parses JSON-encoded speed data

• Designed for hardware integration or IoT-enabled exercise bikes

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XRInput

• Uses XR.InputDevices to read joystick direction from hand-held controllers
• Ideal for VR motion controllers

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Data Flow Summary

Initialization

1. PlayerController checks input method and selects IPlayerInput.
2. Retrieves or overrides the movement handler (IBikeMover) based on preferences.
3. Calls Init() to link the movement handler with the current bike model.

Runtime Loop

• FixedUpdate():

  • Gets input via IPlayerInput.GetDirection()
  • Passes input to IBikeMover.HanldeInput()
  • Movement logic is executed (e.g., wheel torque, transform rotation)