How to update the Geometry vertex position Objloader

问题

I am using objloader to load multiple objects. I am trying to move one of the objects and need to have the updated vertex positions. while loading the objects I converted the buffergeometry to geometry and run some functions. I checked some samples all updating the vertices of the buffergeometry. Do I need to convert it back to buffergeometry or not ? I need to have the real time positions while moving to calculate some other functions, so I prefer not to keep on converting from buffer to geometry and vice versa.

Here is a piece of code:

          var tool= new THREE.OBJLoader();
          tool.load( '../obj/tool.obj', function ( object ) {
          var material = new THREE.MeshLambertMaterial({color:0xA0A0A0});             
          object.traverse( function ( child ) {
          if ( child instanceof THREE.Mesh ) {
               child.material = material;
               Geometry = new THREE.Geometry().fromBufferGeometry(child.geometry);
              }

          console.log(Geometry.vertices[220]);
          Geometry.position.x += 0.01;
          Geometry.verticesNeedUpdate = true;
          console.log(Geometry.vertices[220]);

Besides, I checked the migration document of the latest versions and checked them out.

回答1:

OBJLoader returns BufferGeometry. You can update a vertex position like so:

geometry.attributes.position.setX( index, x );

geometry.attributes.position.setXYZ( index, x, y, z ); // alternate

geometry.attributes.position.needsUpdate = true; // only required if geometry previously-rendered

Study http://threejs.org/docs/#Reference/Core/BufferAttribute

Instead, you can convert to Geometry. In your case, do the following in the loader callback:

child.geometry = new THREE.Geometry().fromBufferGeometry( child.geometry );

You then update a vertex position using this pattern:

geometry.vertices[ 0 ].set( x, y, z );
geometry.verticesNeedUpdate = true;

Only set the needsUpdate flag if the geometry has been previously rendered.

three.js r.71

来源：https://stackoverflow.com/questions/31859819/how-to-update-the-geometry-vertex-position-objloader

标签

three.js

geometry

updates

vertices