Three.js 不拉伸网格纹理（图像） - 使其覆盖其容器

Question

我有一个容器，我使用 three.js 和网格将图像应用到该容器。

这就是我将网格应用于场景的方式：

this.$els = {
    el: el,
    image: el.querySelector('.ch__image') <-- size of container image is being applied to
};

this.loader = new THREE.TextureLoader();
this.image = this.loader.load(this.$els.image.dataset.src);
this.sizes = new THREE.Vector2(0, 0);
this.offset = new THREE.Vector2(0, 0);

getSizes() {
    const { width, height, top, left } = this.$els.image.getBoundingClientRect();

    this.sizes.set(width, height);
    this.offset.set(left - window.innerWidth / 2 + width / 2, -top + window.innerHeight / 2 - height / 2)
}

createMesh() {
    this.geometry = new THREE.PlaneBufferGeometry(1, 1, 1, 1);
    this.material = new THREE.MeshBasicMaterial({
        map: this.image
    });

    this.mesh = new THREE.Mesh(this.geometry, this.material);

    this.mesh.position.set(this.offset.x, this.offset.y, 0);
    this.mesh.scale.set(this.sizes.x, this.sizes.y, 1);

    this.scene.add(this.mesh)
}

目前正在拉伸图像/纹理以适应容器 - 我怎样才能使行为像 object-fit: cover 或 background-size: cover？

Answer 1

我创建了一个 Canvas 元素，并通过 CanvasContext.drwaImage 编辑图像的大小，然后制作一个 CanvasTexture。有效

import * as THREE from 'three';

function createCoverTexture(
  url: string,
  width: number,
  height: number
): Promise<THREE.CanvasTexture> {
  return new Promise((resolve, reject) => {
    const aspect = width / height;

    const image = new Image();
    image.crossOrigin = 'anonymous';

    image.onload = () => {
      const [sw, sh, left, top] =
        image.height < image.width / aspect
          ? [
              image.height * aspect,
              image.height,
              image.width / 2 - (image.height * aspect) / 2,
              0,
            ]
          : [
              image.width,
              image.width / aspect,
              0,
              image.height / 2 - image.width / aspect / 2,
            ];

      const canvas = document.createElement('canvas');
      const ctx = canvas.getContext('2d');
      canvas.width = sw;
      canvas.height = sh;

      ctx?.drawImage(image, left, top, sw, sh, 0, 0, sw, sh);

      resolve(new THREE.CanvasTexture(canvas));
    };

    image.onerror = reject;

    image.src = url;
  });
}

Answer 2

尝试使用此代码 sn-p 中提供的 cover() 函数。这个想法是使用容器和图像的方面来实现类似的结果，如background-size: cover。

var camera, scene, renderer;

var texture;

init();
animate();

function init() {

    camera = new THREE.PerspectiveCamera( 70, window.innerWidth / window.innerHeight, 0.01, 10 );
    camera.position.z = 1;

    scene = new THREE.Scene();

    texture = new THREE.TextureLoader().load( 'https://threejs.org/examples/textures/crate.gif', () => {
    
      cover( texture, window.innerWidth / window.innerHeight );
    
      scene.background = texture;
    
    } );
    texture.matrixAutoUpdate = false;

    renderer = new THREE.WebGLRenderer( { antialias: true } );
    renderer.setSize( window.innerWidth, window.innerHeight );
    document.body.appendChild( renderer.domElement );
    
    window.addEventListener( 'resize', onWindowResize, false );

}

function onWindowResize() {

  var aspect = window.innerWidth / window.innerHeight;

  camera.aspect = aspect;
  camera.updateProjectionMatrix();
  
  cover( texture, aspect );

  renderer.setSize( window.innerWidth, window.innerHeight );

}

function cover( texture, aspect ) {

  var imageAspect = texture.image.width / texture.image.height;

  if ( aspect < imageAspect ) {

      texture.matrix.setUvTransform( 0, 0, aspect / imageAspect, 1, 0, 0.5, 0.5 );

  } else {

      texture.matrix.setUvTransform( 0, 0, 1, imageAspect / aspect, 0, 0.5, 0.5 );

  }

}

function animate() {

    requestAnimationFrame( animate );
    renderer.render( scene, camera );

}

body {
  margin: 0;
 }
 canvas {
  display: block;
 }

<script src="https://cdn.jsdelivr.net/npm/three@0.115/build/three.js"></script>

顺便说一句：不要使用window.innerWidth 和window.innerHeight，而是使用容器的尺寸。