threejs-interaction

Mouse and touch picking in Three.js uses raycasting with normalized device coordinate conversion to detect intersections. This approach maps screen clicks to 3D world coordinates, retrieving the intersected object, face, and UV information for reliable click and hover interactions across devices.

OrbitControls in Three.js integrate damping, limits, and update patterns for smooth camera movement. Touch fallback ensures mobile compatibility, while update loops maintain responsive rotation, zoom, and panning for interactive 3D applications.

Click-to-select and drag interactions in Three.js combine raycasting for object detection with transform gizmos and drag controls. This enables editor-style workflows where users click parts to inspect, use box selection, and drag components with hover feedback.

Optimize raycasting in Three.js by throttling input events, filtering object layers to reduce intersection tests, and using collision proxy meshes. These practices minimize computational overhead when checking for object intersections during interactions.

Three.js supports PointerLockControls, FlyControls, TrackballControls, and MapControls for camera movement. These integrate with keyboard input for first-person navigation, providing damping and update patterns for interactive browser-based 3D applications.

Screen-to-world coordinate conversion in Three.js uses normalized device coordinates to cast rays through the camera frustrum. Ray-plane intersection calculations determine exact 3D positions from 2D pointers, enabling precise drag-and-drop placement.