Implementing Smooth Camera Transitions in Three.js

To create a smooth camera transition instead of the instant snap to a new target, you can use linear interpolation (lerp) with Three.js's Vector3 class. Here's how to modify your code to achieve a gradual camera movement:

Solution

First, you'll need to track both the current target and the destination target, then update the camera position in your animation loop:

JAVASCRIPTCopied
// Add these variables to your global scope
let currentTarget = new THREE.Vector3();
let targetPosition = new THREE.Vector3();
let isTransitioning = false;
let transitionSpeed = 0.05; // Adjust for faster/slower transitions

// Modify your double-click function
function ondblclick(event) {
    pointer.x = (event.clientX / window.innerWidth) * 2 - 1;
    pointer.y = -(event.clientY / window.innerHeight) * 2 + 1;
    raycaster.setFromCamera(pointer, camera);
    const intersects = raycaster.intersectObjects(scene.children);
    
    if (intersects.length > 0) {
        // Store the current target
        currentTarget.copy(controls.target);
        
        // Set the new target position
        targetPosition.set(0, 0, 0);
        intersects[0].object.getWorldPosition(targetPosition);
        
        // Start the transition
        isTransitioning = true;
    }
}

// Add this to your animation loop (requestAnimationFrame function)
function animate() {
    requestAnimationFrame(animate);
    
    // Handle camera transition
    if (isTransitioning) {
        // Interpolate the current target toward the target position
        currentTarget.lerp(targetPosition, transitionSpeed);
        
        // Update the controls target
        controls.target.copy(currentTarget);
        
        // Check if we're close enough to the target to end the transition
        if (currentTarget.distanceTo(targetPosition) < 0.01) {
            isTransitioning = false;
            controls.target.copy(targetPosition);
        }
        
        // Important: update controls after changing the target
        controls.update();
    }
    
    renderer.render(scene, camera);
}

Explanation

1. We create three variables:

   • currentTarget: Tracks the current position of the camera's focus
   • targetPosition: Stores the destination we want to move to
   • isTransitioning: A flag to indicate when we're in the middle of a camera transition

2. In the double-click handler, instead of immediately setting controls.target, we:

   • Store the current target position
   • Set the new target position
   • Enable the transition flag

3. In the animation loop, we:

   • Check if we're transitioning
   • Use Vector3's lerp() method to smoothly interpolate between the current and target positions
   • Update the controls target with the interpolated position
   • End the transition when we're close enough to the target

You can adjust the transitionSpeed value to control how quickly the camera moves to its new target. Lower values create slower, smoother transitions, while higher values make the camera move more quickly.

This approach creates a smooth, professional-looking camera transition that will greatly improve the user experience in your Three.js application.