How can I preserve constant size of meshes regardless of perspective using Three.js?
Lets assume I have multiple meshes of the same size. I want them to always have the same on screen size. I also have to use perspective camera.
I have found some related answers, but seems that I miss something:
First approach is to use Euclidean distance to objects from camera and scale them respectively every animation frame. Three JS Keep Label Size On Zoom
I have tried to modify jsfiddle given in the answer to apply scale to meshes instead of sprites, but that doesn't work for me. The result looks as follows https://jsfiddle.net/a2ogz9vx/258/
var camera, scene, renderer, controls;
var planets = [];
var timestamp = 0;
var scaleVector = new THREE.Vector3();
init();
animate();
function init() {
scene = new THREE.Scene();
camera = new THREE.PerspectiveCamera(90, window.innerWidth / window.innerHeight, 1, 10000);
camera.position.set(0, 100, 100);
renderer = new THREE.WebGLRenderer({
antialias: true
});
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);
controls = new THREE.OrbitControls(camera, renderer.domElement);
var createPlanet = function(name, radius, orbit, speed) {
var geom = new THREE.SphereGeometry(radius, 32, 16);
var mat = new THREE.MeshBasicMaterial({
color: Math.random() * 0xFFFFFF,
});
var planet = new THREE.Mesh(geom, mat);
planet.userData.orbit = orbit;
planet.userData.speed = speed;
var canvas = document.createElement('canvas');
canvas.width = 256;
canvas.height = 256;
var tex = new THREE.Texture(canvas);
tex.needsUpdate = true;
var spriteMat = new THREE.SpriteMaterial({
map: tex
});
var sprite = new THREE.Sprite(spriteMat);
planet.add(sprite);
planets.push(planet);
scene.add(planet);
};
createPlanet("One", 11, -10, 5);
createPlanet("Two", 11, 5, 5);
createPlanet("Three", 11, 10, 5);
}
function animate() {
requestAnimationFrame(animate);
planets.forEach(function(planet) {
var scaleFactor = 100;
var scale = scaleVector.subVectors(planet.position, camera.position).length() / scaleFactor;
planet.scale.set(scale, scale, scale);
var orbit = planet.userData.orbit;
var speed = planet.userData.speed;
planet.position.x = speed * orbit;
planet.position.z = speed * orbit;
});
render();
}
function render() {
renderer.render(scene, camera);
}
<script src="https://cdn.rawgit.com/mrdoob/three.js/master/build/three.min.js"></script>
<script src="https://cdn.rawgit.com/mrdoob/three.js/master/examples/js/controls/OrbitControls.js"></script>
- Second approach is to use on screen width calculation. https://stackoverflow.com/a/13351534/8465699 Result also doesn't look right https://jsfiddle.net/a2ogz9vx/260/
var camera, scene, renderer, controls;
var planets = [];
var timestamp = 0;
var scaleVector = new THREE.Vector3();
init();
animate();
function init() {
scene = new THREE.Scene();
camera = new THREE.PerspectiveCamera(90, window.innerWidth / window.innerHeight, 1, 10000);
camera.position.set(0, 100, 100);
renderer = new THREE.WebGLRenderer({
antialias: true
});
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);
controls = new THREE.OrbitControls(camera, renderer.domElement);
var createPlanet = function(name, radius, orbit, speed) {
var geom = new THREE.SphereGeometry(radius, 32, 16);
var mat = new THREE.MeshBasicMaterial({
color: Math.random() * 0xFFFFFF,
});
var planet = new THREE.Mesh(geom, mat);
planet.userData.orbit = orbit;
planet.userData.speed = speed;
var canvas = document.createElement('canvas');
canvas.width = 256;
canvas.height = 256;
var tex = new THREE.Texture(canvas);
tex.needsUpdate = true;
var spriteMat = new THREE.SpriteMaterial({
map: tex
});
var sprite = new THREE.Sprite(spriteMat);
planet.add(sprite);
planets.push(planet);
scene.add(planet);
};
createPlanet("One", 11, -10, 5);
createPlanet("Two", 11, 0, 5);
createPlanet("Three", 11, 10, 5);
}
function animate() {
requestAnimationFrame(animate);
planets.forEach(function(planet) {
const dist = planet.position.distanceTo(camera.position);
const vFOV = THREE.Math.degToRad(camera.fov);
const size = 2 * Math.tan(vFOV / 2) * dist;
const scaleFactor = 130;
const scale = size / scaleFactor;
planet.scale.set(scale, scale, scale);
var orbit = planet.userData.orbit;
var speed = planet.userData.speed;
planet.position.x = speed * orbit;
planet.position.z = speed * orbit;
});
render();
}
function render() {
renderer.render(scene, camera);
}
<script src="https://cdn.rawgit.com/mrdoob/three.js/master/build/three.min.js"></script>
<script src="https://cdn.rawgit.com/mrdoob/three.js/master/examples/js/controls/OrbitControls.js"></script>
Any suggestions how to fix the code or other approaches are welcome!