Navigating Three.js coordinate systems

Question

Navigating Three.js coordinate systems

While working with vectors in three.js, I noticed that the axes seem to be mixed up. It's confusing because Y is the vertical axis, but X and Z appear "mirrored" causing objects to only look right when viewed upside-down. How can this issue be resolved? Rotating the camera representation/objects might not suffice - I require a complete change in the World X Y Z representation.

The program is built using:

<script src="jquery-2.1.4.js"></script>
<script src="jquery.blockUI.js"></script>
<script src="getparam.js"></script>    
<script src="dat.gui.js"></script>
<script src="three.js"></script>
<script src="OrbitControls.js"></script>
<script src="Stats.js"></script>
<script src="Program.js"></script>

I am unsure about which part of the code needs modification.

This represents the incorrect JS orientation: https://i.sstatic.net/yCmTo.png This is how it should ideally look: https://i.sstatic.net/S11Vb.png

javascript three.js

Answer 1

Answer №1

It seems like you're looking for a specific behavior, perhaps try adjusting the up vector for the camera to achieve the desired effect. For example:

camera.up(0, 0, 1);

In this code snippet, we assume that camera refers to the camera being used for rendering, and that you want the Z-axis to be considered as "up". To observe how this change impacts the scene, check out this simple JSFiddle example here:

// JavaScript code demonstrating camera adjustments
var scene, camera, cube, light;

initialize();
animate();

function initialize() {
  var height = 500;
  var width = 500;
  var background = '#000000';

  scene = new THREE.Scene();

  var axisHelper = new THREE.AxisHelper(50);
  scene.add(axisHelper);

  // Setting up the camera
  camera = new THREE.PerspectiveCamera(50, height / width, 1, 10000);
  camera.position.set(20, 20, 20);
  // Uncomment next line if specifying up vector directly
  // camera.up = new THREE.Vector3(0, 0, 1);
  camera.lookAt(axisHelper.position);
  scene.add(camera);

  renderer = new THREE.WebGLRenderer({ antialias: true });
  renderer.setClearColor(background);
  renderer.setSize(width, height);

  var container = document.createElement('div');
  document.body.appendChild(container);
  container.appendChild(renderer.domElement);
  var canvas = document.getElementsByTagName('canvas')[0];
  canvas.style.width = width + 'px';
  canvas.style.height = height + 'px'
}

function animate() {
  requestAnimationFrame(animate);
  render();
}

function render() {
  renderer.render(scene, camera);
}

This script displays an AxisHelper representing orientation (red for x-axis, green for y-axis, blue for z-axis). Try uncommenting the line that sets the camera's up vector and re-run the code to observe the differences visually.

Answer 2

It seems like you're looking for a specific behavior, perhaps try adjusting the up vector for the camera to achieve the desired effect. For example:

camera.up(0, 0, 1);

In this code snippet, we assume that camera refers to the camera being used for rendering, and that you want the Z-axis to be considered as "up". To observe how this change impacts the scene, check out this simple JSFiddle example here:

// JavaScript code demonstrating camera adjustments
var scene, camera, cube, light;

initialize();
animate();

function initialize() {
  var height = 500;
  var width = 500;
  var background = '#000000';

  scene = new THREE.Scene();

  var axisHelper = new THREE.AxisHelper(50);
  scene.add(axisHelper);

  // Setting up the camera
  camera = new THREE.PerspectiveCamera(50, height / width, 1, 10000);
  camera.position.set(20, 20, 20);
  // Uncomment next line if specifying up vector directly
  // camera.up = new THREE.Vector3(0, 0, 1);
  camera.lookAt(axisHelper.position);
  scene.add(camera);

  renderer = new THREE.WebGLRenderer({ antialias: true });
  renderer.setClearColor(background);
  renderer.setSize(width, height);

  var container = document.createElement('div');
  document.body.appendChild(container);
  container.appendChild(renderer.domElement);
  var canvas = document.getElementsByTagName('canvas')[0];
  canvas.style.width = width + 'px';
  canvas.style.height = height + 'px'
}

function animate() {
  requestAnimationFrame(animate);
  render();
}

function render() {
  renderer.render(scene, camera);
}

This script displays an AxisHelper representing orientation (red for x-axis, green for y-axis, blue for z-axis). Try uncommenting the line that sets the camera's up vector and re-run the code to observe the differences visually.

Navigating Three.js coordinate systems

Answer №1

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