how to use camera in three js to follow object

by chandramouliprabuoff Updated: Jan 5, 2024

Guide Kit

Introduction to Three.js Cameras and Their Role in 3D Graphics:

Three.js cameras serve as the visual eyes of a 3D scene. It defines perspectives and enables the creation of immersive graphics and animations.

Basics of Three.js Cameras:

Cameras in Three.js own essential attributes, including position, rotation. the field of view.
These attributes influence how scenes are designed. it presented to viewers, impacting the visual experience.

Types of Cameras in Three.js:

Perspective Camera: Replicates human vision, offering depth. the realism through a realistic field of view.
Orthographic Camera: Provides orthographic projection, suitable for architectural visualization and stylized effects.
Cube Camera: Specialized in rendering scenes to six cube faces. it enables unique visual effects or reflections.

Creating and Manipulating Cameras in Three.js:

Initialization involves creating an instance of the desired camera type. it such as Perspective Camera or Orthographic Camera.
Manipulation includes setting the camera's position and defining its target or look-at point.
It provides developers with precise control over the camera's behavior.

Optimizing Camera Movement in Three.js:

Near and Far Clipping Planes: Strategic change of these parameters enhances performance. It limits the rendering of objects within a specific range.
Careful consideration of clipping planes prevents rendering issues and ensures smooth camera movement.
Leveraging different camera types for specific scenarios optimizes rendering. It balances visual quality and computational efficiency.

Three.js cameras are crucial components for creating immersive 3D graphics and animations. They act as virtual eyes. It determines viewpoints and perspectives within a 3D scene. Cameras in Three.js are present. It has essential attributes like position, rotation, and field of view. Position defines the camera's location, rotation, its orientation. the field of view influences how much of the scene is visible

Perspective Camera: Mimics human vision is predictable. It provides depth and realism with a realistic field of view.
Orthographic Camera: Offers orthographic projection, suitable for certain visual effects and architectural visualization.
Cube Camera: Specialized in rendering scenes to six cube faces. It is often used for reflective surfaces.
Creating a camera involves initializing an instance of the desired camera type. It must set its position and define its target or look-at point.
Manipulation includes adjusting the camera's position. target to control the viewpoint and orientation.
To enhance performance, adjust the camera's near and far clipping planes.
Near and far values control the range of visibility. It prevents rendering issues and ensures smooth camera movement.
Use different camera types for specific scenarios, balancing rendering performance with visual quality.

Beyond the fundamental camera types. the advanced features like Cube Camera, Stereo Camera, and Array Camera. It provides specialized functionalities catering to diverse 3D scenarios. Lambert material contributes to realistic light interactions in materials. ensuring correct positions and directions in a 3D space that mirrors the real world.

The HTML file, often employing HTML5, serves as the canvas for WebGL rendering. It creates a bridge between the 3D world and the web application. Techniques like the Pointer Lock API enhance user interactions, and the Field of View (FOV). It determines the extent of the observable scene.

Clipping planes, defined by parallel rays and an aspect ratio. It is used to control what is viewable from the camera's perspective. The cube, representing a basic 3D shape, extends into the depth of the scene. For frameworks like React, integration with Three.js are present. It enhances the development of interactive 3D web applications. offering new viewpoints and angles for a richer user experience.

Fig 1: Preview of the output that you will get on running this code from your IDE.

Code

Three.JS Rotate Camera around object by moving the device

JavaScriptLines of Code : 172License : Strong Copyleft (CC BY-SA 4.0)

Dependent Libraries :

<body>
<canvas id="mCanvas">
</canvas>
</body>
<script src="https://threejs.org/build/three.js"></script>
<script>
// Var Init
    var renderer, scene, camera, box, transformControl, orbitControl, geometry, material, poseMatrix;
    var mPoints = [];
    //Box coordinate
    var xBCordinate, yBCordinate, zBCordinate, isScaled, posVec, startPosVec, lookPos, helper;
    var process = false;
    var scanActive = false;
    var pointArr = [];
    
    var cameraSpherical;
    
     init();
    animate();

  function init() {

        // renderer
       renderer = new THREE.WebGLRenderer({canvas: document.getElementById("mCanvas"),
            alpha: true});
       renderer.setSize( window.innerWidth, window.innerHeight );
       document.body.appendChild( renderer.domElement );
        renderer.setClearColor(0xffffff, 0);
        renderer.setSize(window.innerWidth, window.innerHeight);
        document.body.appendChild(renderer.domElement);

        // scene
        scene = new THREE.Scene();

        // camera
        camera = new THREE.PerspectiveCamera(
            45,
            window.innerWidth / window.innerHeight,
            0.1,
            1000
        );

        camera.up.set(0, 0, 1); // Definition of coordinationsystem
        
        // set initial scale position of camera 
        camera.position.x = 0;
        camera.position.y = -0.5;
        camera.position.z = 0.15;  
        
        scene.add(camera);
        
        cameraSpherical = new THREE.Spherical( camera.position );
        
        // set position to look at 
        camera.lookAt(0,2.5,-0.2);
        
        // apply values
        camera.updateMatrix();

        // light
        var light = new THREE.HemisphereLight( 0xeeeeee, 0x888888, 1 );
        light.position.set( 0, -0.75, 2.5 );
        scene.add(light);


        placeBox();


    }
    function placeBox()
    {
        

        geometry = new THREE.BoxGeometry(0.5, 1, 0.5); //3,5,3
        material = new THREE.MeshLambertMaterial({color: 0xfece46});
        
        box = new THREE.Mesh(geometry, material);
        
        box.position.set(0, 0, 0);
        box.updateMatrix();
        scene.add(box);

    }
    function animate() {
        requestAnimationFrame(animate);
        if(process == false){
        setCurrentPose();
        }

        renderer.render(scene, camera);
    }
    
    function setCurrentPose(){
        process = true;
        
        // this is where I receive the position data via Android
        // but lets try using random numbers between 0.01 - 0.99 (which are the results interval of dso)
        
        moveRotateCamera();
    }
      function moveRotateCamera(){
       // Create Vector to work with
      /* posVec = new THREE.Vector3();
          
       posVec.x = getRandomFloat(0.01, 0.05);
       posVec.y = getRandomFloat(0.01, 0.05);
       posVec.z = getRandomFloat(0.01, 0.02);
    
          
        camera.position.x += posVec.x;
        camera.position.y += posVec.y; // minus initial scale position 
        camera.position.z += posVec.z; 
        */
        cameraSpherical.radius = 5;
        cameraSpherical.phi += getRandomFloat(0.001, 0.015);
        cameraSpherical.theta += getRandomFloat(0.001, 0.015);
        let xyz = new THREE.Vector3().setFromSpherical( cameraSpherical );
        camera.position.x = xyz.x;
        camera.position.y = xyz.y;
        camera.position.z = xyz.z;
        
        camera.lookAt(0,0,0);
        
        camera.updateMatrix();
        
        
        
     //   camera.updateMatrix(); <- seem to change nothing such as UpdateWorldMatrix() etc.    
     
     // camera rotation tried to calculate with quaternions (result NaN) and/or euler by using former and current point.
        process = false;
    }
    function getRandomFloat(min, max) {
  return Math.random() * (max - min) + min;
}   


// My attempts in trying to calculate the rotation
/*
function setQuaternionRotation(poseMatrix){
        // TODO: delete if not needed!
        // adapted from http://www.euclideanspace.com/maths/geometry/rotations/conversions/matrixToQuaternion/index.htm, 2.12.2019, 2.34pm
        mQuaternion = new THREE.Quaternion();

        // Calculate Angle w
        mQuaternion.w = ((Math.sqrt(Math.max(0, (1.0 + poseMatrix.elements[0] + poseMatrix.elements[5] + poseMatrix.elements[10])))/2.0));

        //Sign x,y,z values of quaternion
        mQuaternion.x = ((Math.sqrt(Math.max(0, (1.0 + poseMatrix.elements[0] - poseMatrix.elements[5] - poseMatrix.elements[10])))/2.0));
        mQuaternion.y = ((Math.sqrt(Math.max(0, (1.0 - poseMatrix.elements[0] + poseMatrix.elements[5] - poseMatrix.elements[10])))/2.0));
        mQuaternion.y = ((Math.sqrt(Math.max(0, (1.0 - poseMatrix.elements[0] - poseMatrix.elements[5] + poseMatrix.elements[10])))/2.0));

        //Sign element values
        mQuaternion.x = (Math.sign(mQuaternion.x * (poseMatrix.elements[6] - poseMatrix.elements[9])));
        mQuaternion.y = (Math.sign(mQuaternion.y * (poseMatrix.elements[8] - poseMatrix.elements[2])));
        mQuaternion.z = (Math.sign(mQuaternion.z * (poseMatrix.elements[1] - poseMatrix.elements[4])));

        // debug
        console.log("QuaternionVal: "+mQuaternion.x+ ", " +mQuaternion.y+", "+mQuaternion.z+", "+mQuaternion.w);

        camera.applyQuaternion(mQuaternion);
        camera.quaternion.normalize();


        // debug
        console.log("newCamRotation: "+camera.rotation.x +", "+camera.rotation.y+", "+ camera.rotation.z);

   //     camera.updateMatrix(true);
    }
   
*/
    </script>

Instruction

Install Visual Studio Code IDE on your computer.
Create a new HTML file.
Copy the code using the 'Copy' button and create an HTML tag then paste the code inside the tag into that HTML file.
Copy the controller.js code and paste in the JS file created.
Create a script tag inside the body tag Then keep the function lines inside the script tag(refer to preview as well).
⁠Add the script tag from line 1 to 15.
Save and run the HTML file directly from the file location to generate the output

I found this code snippet by searching for 'how to use camera in three js to follow object' .you can try any such use case!

Environment Tested

I tested this solution in the following versions. Be mindful of changes when working with other versions.

The solution is created in Visual Studio Code 1.75.1.

Using this solution, we are able to process form using angular js with simple steps. This process also facilities an easy way to use, hassle-free method to create a hands-on working version of code which would help us to use camera in three js to follow object.

FAQ

1. What is the role of WebGL in creating and manipulating cameras in Three JS?

WebGL is the underlying technology in Three.js. It provides a platform for hardware-accelerated rendering of 3D graphics in web browsers. It enables efficient creation and manipulation of cameras in Three.js. This allows developers to define viewpoints, perspectives, and interactive 3D experiences.

2. How can you adjust the position of a camera using Three JS?

In Three.js, you can change a camera's position by setting its coordinates. Use the position property. For example, camera.position.set(x, y, z) changes the camera's location in the scene along the x, y, and z axes. It offers precise control over the viewpoint.

3. In what ways does the library of Three JS support many cameras for a 3D scene?

Three.js provides a versatile camera system. It allows the integration of many cameras into a 3D scene. Developers can instantiate various camera types like Perspective Camera or Orthographic Camera. This enables different viewpoints and rendering perspectives within the same scene.

4. What are the differences between an orthographic camera and a perspective camera in Three JS?

An orthographic camera renders objects with uniform size, disregarding depth. This makes it suitable for technical or architectural visualization.
The perspective camera mimics human vision. It creates a sense of depth and realism by rendering objects based on their distance from the camera.

5. How can Three JS use HTML canvas to display many views from different cameras?

In Three.js, you can create many renderer instances. Use them to showcase views from different cameras on an HTML canvas. A specific camera associates with each renderer. Render the scene using each camera. Display the results on separate canvas elements. This approach allows presenting diverse perspectives in a web application.

Support

For any support on kandi solution kits, please use the chat
For further learning resources, visit the Open Weaver Community learning page.

Open Weaver – Develop Applications Faster with Open Source

Terms
Privacy policy

how to use camera in three js to follow object

Code

Instruction

Environment Tested

FAQ

Support

Open Weaver – Develop Applications Faster with Open Source

kandi

Community and Support

Company

Follow