如何从Autodesk Viewer对象中获取顶点坐标等几何数据？

Absolutely, you can get vertex data from a dbId—you just need to combine the two methods you’ve already experimented with! Here’s a step-by-step breakdown to make it work:

Step 1: Map dbId to its associated fragIds #

First, use the fragment list to get all fragIds linked to your target dbId. Keep in mind a single dbId might be split across multiple fragments, so you’ll get an array of fragIds:

const fragmentList = viewer.model.getFragmentList();
const fragIds = fragmentList.dbId2fragId[targetDbId]; // Returns an array of frag IDs

Step 2: Extract vertex data from each fragment #

For each fragId in the array, fetch the fragment proxy (like you did before) and then access the underlying THREE.js geometry to pull out vertex positions:

async function getVerticesFromDbId(viewer, dbId) {
  const fragmentList = viewer.model.getFragmentList();
  const fragIds = fragmentList.dbId2fragId[dbId];
  
  if (!fragIds || fragIds.length === 0) return [];

  const allVertices = [];

  for (const fragId of fragIds) {
    // Make sure the fragment is loaded (critical for large models)
    if (!fragmentList.isFragmentLoaded(fragId)) {
      await new Promise(resolve => {
        viewer.impl.loadFragment(viewer.model, fragId, resolve);
      });
    }

    // Get the fragment proxy and update its transform
    const fragProxy = viewer.impl.getFragmentProxy(viewer.model, fragId);
    fragProxy.updateAnimTransform(); // Ensures vertices are in world space

    // Access the THREE.js mesh and its geometry
    const mesh = fragProxy.getMesh();
    if (!mesh || !mesh.geometry) continue;

    // Extract raw vertex data (flat array: x1, y1, z1, x2, y2, z2, ...)
    const positionArray = mesh.geometry.attributes.position.array;
    allVertices.push(...Array.from(positionArray));
  }

  // Optional: Convert flat array into [x, y, z] tuples for easier use
  const vertexTuples = [];
  for (let i = 0; i < allVertices.length; i += 3) {
    vertexTuples.push([allVertices[i], allVertices[i+1], allVertices[i+2]]);
  }

  return vertexTuples;
}

Key Notes: #

• World vs Local Space: Calling fragProxy.updateAnimTransform() gives you vertices in world space (aligned with the viewer’s coordinate system). Skip this if you need vertices in the fragment’s local space.
• Loading Fragments: For large models, some fragments might not be loaded initially. The async wait ensures we don’t try to access unloaded data.
• Edge Cases: Complex or instanced geometries might need extra handling, but this works for most standard model components.

内容的提问来源于stack exchange，提问作者Daniel Ignjat