CODEWITHSUNDEEP
reactjsthree.jsphysicsreact-fiberrapier
Nati
Nati

Reputation: 148

How do I control the movement of a cube?

I am using 3D (Three.js) and physics (Rapier), and I want to control the box movement like a car, with arrow keys, but I have difficulty fixing the movement in the right direction with physics.

Here is a code example https://codesandbox.io/s/q-stackoverflow-9j4sf1

What do I need to insert inside useFrame?

useFrame:

useFrame((state, delta) => {
if (ref.current) {
  const box = ref.current;
  /// what i should insert in this area
  // w/ArrpUP click
  if (controllers.forward.isPress) {
  //  What do I need to insert so that the box moves forward
  }
  // s/ArrpDown click
  if (controllers.backward.isPress) {
 //  What do I need to insert so that the box moves backward
  }
  // L/ArrpLeft click
  if (controllers.left.isPress) {
    //  What do I need to insert so that the box rotate left
  }
  // R/ArrpRight click
  if (controllers.right.isPress) {
     //  What do I need to insert so that the box rotate right
  }
}});

Upvotes: 2

Views: 345

Answers (1)

doppler
doppler

Reputation: 883

The Kinematic Character Controller is a higher-level tool that will emit the proper ray-casts and shape-casts to adjust the user-defined trajectory based on obstacles. Character controller guide

Use the DynamicRayCastVehicleController class for a more realistic vehicle simulation: DynamicRayCastVehicleController

Here is a basic JS example of the Character Controller using your useFrame loop function. You may want to replace the Cuboid with a Capsule for smoother results.

// Create a basic world with all your obstacles
let world = new RAPIER.World({ x: 0.0, y: -9.81, z: 0.0 });

// Initialize your character rigid body and collider
let rigidBodyDesc = new RAPIER.RigidBodyDesc(RAPIER.RigidBodyType['KinematicPositionBased']);
let rigidBody = world.createRigidBody(rigidBodyDesc);
let colliderDesc = new RAPIER.ColliderDesc(RAPIER.Cuboid(0.5, 0.5, 0.5));
let collider = world.createCollider(colliderDesc, rigidBody);

// Initialize your character controller and conditions
let characterController = world.createCharacterController(0.01);
let velocity = new THREE.Vector3();
let movement = new THREE.Vector3();
let nextTranslation = new THREE.Vector3();
let speed = 5;

// Define your loop function
useFrame((state, delta) => {
if (ref.current) {
  // Simulate gravity
  velocity.y -= delta;

  // Simulate movement damping
  velocity.z *= 0.5;
  velocity.x *= 0.5;

  // Update velocity from keyboard input
  if (controllers.forward.isPress) velocity.z -= delta * speed;
  if (controllers.backward.isPress) velocity.z += delta * speed;
  if (controllers.left.isPress) velocity.x -= delta * speed;
  if (controllers.right.isPress) velocity.x += delta * speed;

  // Calculate collider movement
  controller.computeColliderMovement(collider, velocity);

  // (optional) Check collisions
  for (var i = 0; i < controller.numComputedCollisions(); i++) {
    let collision = controller.computedCollision(i);
  }

  // Calculate next translation from computed movement
  movement.copy(controller.computedMovement());
  nextTranslation.copy(rigidBody.translation());
  nextTranslation.add(movement);
  rigidBody.setNextKinematicTranslation(nextTranslation);
}});

Upvotes: 1

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