How do I put limits on OrbitControl?

In ThreeJS, OrbitControls is a widely used method for rotating, zooming, and panning the camera around a specific object within the scene. To restrict OrbitControls, you can adjust multiple parameters to customize user interaction for different scenarios. Below, I will detail several common restriction methods:

1. Restricting Rotation Angle

OrbitControls enables restricting the horizontal rotation angle using minAzimuthAngle and maxAzimuthAngle, and the vertical rotation angle using minPolarAngle and maxPolarAngle.

For example, if you want the camera to rotate only within the front hemisphere of the object, set:

javascript
controls.minAzimuthAngle = -Math.PI / 2;
controls.maxAzimuthAngle = Math.PI / 2;
controls.minPolarAngle = 0;
controls.maxPolarAngle = Math.PI;

2. Restricting Zoom Range

By setting minDistance and maxDistance, you can limit the minimum and maximum distance of the camera from the target point during zooming. This prevents users from zooming too close or too far, which could compromise visual quality or user experience.

For example, to set the zoom range between 10 and 1000 units:

javascript
controls.minDistance = 10;
controls.maxDistance = 1000;

3. Restricting Translation

In certain scenarios, you may want to prevent users from translating the camera, which can be achieved by disabling the translation feature.

javascript
controls.enablePan = false;

Example Application Scenario

Suppose you are developing an online globe application where users can browse the entire Earth, but you do not want them to move the view inside the Earth or into distant space. Configure OrbitControls as follows:

javascript
// Initialize camera and OrbitControls
var camera = new THREE.PerspectiveCamera(45, window.innerWidth/window.innerHeight, 1, 10000);
var controls = new THREE.OrbitControls(camera, renderer.domElement);

// Restrict camera angles to stay above the Earth
controls.minPolarAngle = 0; // Vertical downward angle is 0
controls.maxPolarAngle = Math.PI; // Vertical upward angle is π

// Set minimum and maximum distance from Earth
controls.minDistance = 10;
controls.maxDistance = 500;

// Disable translation
controls.enablePan = false;

With these settings, you effectively constrain the user's operational range, ensuring a seamless user experience and visual quality.