When building 3D scenes in React using Three.js, your choice of camera dramatically affects how users perceive the scene. The two main camera types in Three.js are the perspective camera and the orthographic camera. The perspective camera simulates the way the human eye sees, where objects appear smaller as they are farther away, creating a sense of depth. This camera is commonly used for most 3D visualizations, games, and simulations. In contrast, the orthographic camera projects objects without perspective, so objects retain their size regardless of distance from the camera. This is useful for architectural plans, CAD applications, or any visualization where accurate scale is more important than depth perception.

To create a perspective camera in Three.js, you typically specify a field of view, aspect ratio, and near and far clipping planes. The orthographic camera, on the other hand, requires you to define the left, right, top, bottom, near, and far planes, which together determine the visible area. Choosing between these camera types depends on the needs of your application and the visual effect you want to achieve.

Once you have selected the appropriate camera, positioning and moving the camera is crucial for framing your 3D scene. In Three.js, you set the camera's position property, which is a vector specifying the x, y, and z coordinates. You can also use the lookAt method to point the camera at a specific object or location in the scene.

When integrating Three.js into a React application, you manage camera properties reactively. This means you can update the camera's position, target, or other parameters in response to React state or props. For example, you might store the camera's position in state and update it when the user interacts with a UI control. When the state changes, React re-renders the component, and you update the camera's properties accordingly. This approach allows you to create smooth camera movements and interactive experiences that respond to user actions or application logic.