Maintain aspect on Three.js texture - three.js

Question

I'm trying to keep a texture centered when it's shown in a different sized box.
I've seen this answer
Three.js: Make image texture fit object without distorting or repeating
But it's not quite doing it for me.
this.texture = new THREE.Texture(this.image)
const vec = new THREE.Vector3()
new THREE.Box3().setFromObject( this.rounded ).getSize(vec)
const imageAspect = this.image.width/this.image.height
const boxAspect = vec.x/vec.y
this.texture.wrapT = THREE.RepeatWrapping;
this.texture.offset.y = 0.5 * ( 1 - boxAspect/imageAspect )
//texture.wrapT = THREE.RepeatWrapping; texture.repeat.x = geometryAspectRatio / imageAspectRatio; texture.offset.x = 0.5 * ( 1 - texture.repeat.x )
this.texture.needsUpdate = true
this.rounded.material = new THREE.MeshPhongMaterial( { map: this.texture, side: THREE.DoubleSide } )
In this aspect the values are
Image: {width:399 height:275}
Texture: {width:1, height: 0.75}
In this aspect the values are
Image: {width:399 height:275}
Texture: {width:2, height: 1}
How do I fix it so the graphic is always central, maintains the aspect and is not distorted?

Answer 1

I hope I got you correctly, here is an option of how you can center it:
var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera(60, innerWidth / innerHeight, 1, 1000);
camera.position.set(0, 0, 10);
var renderer = new THREE.WebGLRenderer();
renderer.setSize(innerWidth, innerHeight);
document.body.appendChild(renderer.domElement);
var planeGeom = new THREE.PlaneBufferGeometry(16, 9);
var planeMat = new THREE.MeshBasicMaterial({
map: new THREE.TextureLoader().load("https://threejs.org/examples/textures/758px-Canestra_di_frutta_(Caravaggio).jpg", tex => {
//console.log(tex);
//console.log(tex.image.width, tex.image.height);
let imgRatio = tex.image.width / tex.image.height;
let planeRatio = planeGeom.parameters.width / planeGeom.parameters.height;
//console.log(imgRatio, planeRatio);
tex.wrapS = THREE.RepeatWrapping; // THREE.ClampToEdgeWrapping;
tex.repeat.x = planeRatio / imgRatio;
tex.offset.x = -0.5 * ((planeRatio / imgRatio) - 1);
})
});
var plane = new THREE.Mesh(planeGeom, planeMat);
scene.add(plane);
renderer.setAnimationLoop(() => {
renderer.render(scene, camera);
})
body {
overflow: hidden;
margin: 0;
}
<script src="https://threejs.org/build/three.min.js"></script>
Addition: how to re-compute UVs for ShapeBufferGeometry
var box = new THREE.Box3().setFromObject(mesh); // mesh with ShapeBufferGeometry
var size = new THREE.Vector3();
box.getSize(size);
var vec3 = new THREE.Vector3(); // temp vector
var attPos = mesh.geometry.attributes.position;
var attUv = mesh.geometry.attributes.uv;
for (let i = 0; i < attPos.count; i++){
vec3.fromBufferAttribute(attPos, i);
attUv.setXY(i,
(vec3.x - box.min.x) / size.x,
(vec3.y - box.min.y) / size.y
);
}
attUv.needsUpdate = true; // just in case