Three.js Beaded Doorway Implementation Help

Based on your questions about implementing a beaded doorway with Three.js and Ammo.js, I'll address each of your concerns:

1. Camera Positioning

To set up your camera to be centered and facing forward:

JAVASCRIPTCopied
// Create a perspective camera
const camera = new THREE.PerspectiveCamera(
  75, // Field of view
  window.innerWidth / window.innerHeight, // Aspect ratio
  0.1, // Near clipping plane
  1000 // Far clipping plane
);

// Position the camera
camera.position.set(0, 0, 10); // Adjust the Z value based on your scene scale
camera.lookAt(0, 0, 0); // Look at the center of the scene

// Handle window resize to maintain centering
window.addEventListener('resize', () => {
  camera.aspect = window.innerWidth / window.innerHeight;
  camera.updateProjectionMatrix();
  renderer.setSize(window.innerWidth, window.innerHeight);
});

2. Stacking CylinderGeometry Objects

For proper alignment of cylindrical beads:

JAVASCRIPTCopied
function createBead(radius, height, position) {
  const geometry = new THREE.CylinderGeometry(
    radius, // Top radius
    radius, // Bottom radius
    height, // Height
    32 // Number of segments
  );
  
  const material = new THREE.MeshStandardMaterial({ color: 0x888888 });
  const bead = new THREE.Mesh(geometry, material);
  
  // Position the bead
  bead.position.copy(position);
  
  // Rotate to align with vertical axis if needed
  bead.rotation.x = Math.PI / 2; // Rotate 90 degrees if needed for vertical alignment
  
  return bead;
}

// Create a string of beads
function createBeadString(beadCount, spacing, startPosition) {
  const beads = [];
  let currentPosition = startPosition.clone();
  
  for (let i = 0; i < beadCount; i++) {
    const bead = createBead(0.5, 1, currentPosition);
    beads.push(bead);
    scene.add(bead);
    
    // Move position for next bead (adjust based on your orientation)
    currentPosition.y -= (1 + spacing); // For vertical strings
  }
  
  return beads;
}

// Create multiple strings
function createBeadCurtain(stringCount, beadsPerString, horizontalSpacing) {
  for (let i = 0; i < stringCount; i++) {
    const startPos = new THREE.Vector3(
      (i - (stringCount - 1) / 2) * horizontalSpacing, // Center the curtain
      10, // Start from top
      0
    );
    createBeadString(beadsPerString, 0.2, startPos);
  }
}

3. Physics Implementation with Ammo.js

For physics integration:

JAVASCRIPTCopied
// Initialize Ammo.js physics
function initPhysics() {
  // Physics configuration
  const collisionConfiguration = new Ammo.btDefaultCollisionConfiguration();
  const dispatcher = new Ammo.btCollisionDispatcher(collisionConfiguration);
  const broadphase = new Ammo.btDbvtBroadphase();
  const solver = new Ammo.btSequentialImpulseConstraintSolver();
  
  physicsWorld = new Ammo.btDiscreteDynamicsWorld(
    dispatcher, broadphase, solver, collisionConfiguration
  );
  physicsWorld.setGravity(new Ammo.btVector3(0, -9.8, 0));
}

// Create a physical bead with collision detection
function createPhysicalBead(radius, height, position) {
  // Create visual object
  const bead = createBead(radius, height, position);
  
  // Create physics shape (cylinder)
  const shape = new Ammo.btCylinderShape(
    new Ammo.btVector3(radius, height/2, radius)
  );
  
  // Create rigid body
  const mass = 1;
  const localInertia = new Ammo.btVector3(0, 0, 0);
  shape.calculateLocalInertia(mass, localInertia);
  
  const transform = new Ammo.btTransform();
  transform.setIdentity();
  transform.setOrigin(new Ammo.btVector3(position.x, position.y, position.z));
  
  const motionState = new Ammo.btDefaultMotionState(transform);
  const rbInfo = new Ammo.btRigidBodyConstructionInfo(
    mass, motionState, shape, localInertia
  );
  
  const body = new Ammo.btRigidBody(rbInfo);
  physicsWorld.addRigidBody(body);
  
  // Store reference to the body
  bead.userData.physicsBody = body;
  
  return bead;
}

// Connect beads with constraints
function connectBeads(beadA, beadB, distance) {
  const bodyA = beadA.userData.physicsBody;
  const bodyB = beadB.userData.physicsBody;
  
  const pivotA = new Ammo.btVector3(0, -distance/2, 0);
  const pivotB = new Ammo.btVector3(0, distance/2, 0);
  
  const constraint = new Ammo.btPoint2PointConstraint(
    bodyA, bodyB, pivotA, pivotB
  );
  
  physicsWorld.addConstraint(constraint);
}

For your specific implementation, you'll need to:

1. Create a physics world
2. Add each bead as a rigid body
3. Connect beads with constraints to simulate strings
4. Update the Three.js objects based on physics simulation in your animation loop

The example you linked (soju22's codepen) uses a different approach with custom physics, but Ammo.js will give you more realistic physics with proper collision detection.

For a complete implementation, you'll need to:

• Initialize Ammo.js
• Create the visual and physical representations of beads
• Set up constraints between beads
• Update the positions in your animation loop
• Handle collisions with other objects

I recommend starting with a simple string of beads to get the physics working correctly before expanding to a full curtain.

Would you like more specific guidance on any of these aspects?