Aframe:模型大小 [英] Aframe: size of model

问题描述

使用模型作为实体的来源时，例如gltf，有没有办法知道原始大小?由于scale属性适用于相对大小，因此尝试将模型拟合为所需大小是一个错误.我尝试使用模型网格的geometry.getComputingBox()，但它返回null.想知道是否有可用的组件让我们以绝对值指定比例.

When using a model as a source to an entity, say gltf, is there a way we know the original size? Since the scale attribute works on relative size, it seems to be a trial an error to fit the model to our desired size. I tried using the geometry.getComputingBox() of the mesh of the model but it returns null. Wondering if there is a component that is available that lets us specify the scale in absolute terms.

推荐答案

(这将作为评论，但由于我没有足够的代表点，这是一个答案.)

(This would have come as a comment but as I don't have enough rep points this is coming as an answer.)

我发现模型在model-loaded事件侦听器之后没有大小，因此我从update方法触发了重新缩放.有趣的是，如果没有model-loaded事件侦听器，则即使在第一个update被触发后，模型的大小也将为0. 这是上面代码的变体，不同之处在于尺寸以米为单位:

I found that the model doesn't have a size directly after the model-loaded event listener so I trigger the rescale from the update method. Funnily enough though if you don't have the model-loaded event listener then the size of the model will be 0 even after the first update is fired. This is my variant of the above code with the difference being that the dimension is set in meters:

const AFRAME = window.AFRAME;

/*
* Scales the object proportionally to a set value given in meters.
*/

AFRAME.registerComponent('natural-size', {
  schema: {
    width: {
      type: "number",
      default: undefined // meters
    },
    height: {
      type: "number",
      default: undefined // meters
    },
    depth: {
      type: "number",
      default: undefined // meters
    }
  },

  init() {
    this.el.addEventListener('model-loaded', this.rescale.bind(this));
  },

  update() {
    this.rescale();
  },

  rescale() {

    const el = this.el;
    const data = this.data;
    const model = el.object3D;

    const box = new THREE.Box3().setFromObject(model);
    const size = box.getSize();

    if ( !size.x && !size.y && !size.z ) {
      return;
    }

    let scale = 1;

    if ( data.width ) {
      scale = data.width / size.x;
    } else if( data.height ) {
      scale = data.height ( size.y);
    } else if( data.depth ) {
      scale = data.depth / size.y;
    }

    el.setAttribute('scale', `${scale} ${scale} ${scale}`);

  },

  remove() {
    this.el.removeEventListener('model-loaded', this.rescale);
  }

});

然后:

<a-entity natural-size='width:0.72' gltf-model='#model`></a-entity>

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