Forge Viewer-无法向场景添加线

Question

I am trying to add some lines into the scene of a 3D model in a Forge Viewer application I am building. I want to draw some bounding boxes around certain objects; I have used the following guide as a baseline:

Getting bounding boxes of each component in the viewer

At the moment I am just using the drawLines function as I already have the coordinate data for the object I want to draw a box around from elsewhere in my code. However, when scene.add is called, the following error appears in console:

WebGL: INVALID_OPERATION: drawArrays: no buffer is bound to enabled attribute

I have looked up this error and can't find anything that can help me. It seems the issue may be due to the fact that my application already adds meshes to the scene, and when it goes to add lines, it uses the same shader, which does not have attributes set up correctly to deal with lines. This is just a guess though, I really have no idea what exactly is causing the error, or what I can do differently to fix it. I have tried various types of THREE.js objects, using sceneAfter, etc, but still cannot draw lines into the scene.

Answer 1

You need to make a new Material like below.

var lineMaterial = new THREE.LineBasicMaterial ({
color: new THREE.Color (0xFF0000),
transparent: true,
depthWrite: false,
depthTest: true,
linewidth: 10,
opacity: 1.0
})

var lines = new THREE.Line (geometry,
lineMaterial)
scene.add (lines)

Answer 2

If you're calling the drawLines function directly, make sure to use the same material type as the tutorial:

let material = new THREE.LineBasicMaterial({ color: 0xffff00, linewidth: 2 });
viewer.impl.matman().addMaterial('MyLineMaterial', material, true);
drawLines([{x:0,y:0,z:0}, {x:10,y:10,z:10}], material);

Answer 3

Aha, managed to get it working! To fix it I had to use createOverlayScene and addOverlay to add the line geometry to the scene instead of using scene.add, and had to remove matman().addMaterial.

Answer 4

make a new scene try ---- just the code （ sorry for my bad english ）

  const geometry = new THREE.Geometry () geometry.vertices.push (new THREE.Vector3 ( 0, 0, 0)) geometry.vertices.push (new THREE.Vector3 (100, 100, 100)) var material = new THREE.LineBasicMaterial({ color: 0x0000ff, linewidth: 2 }); var lines = new THREE.Line (geometry, material) viewer.impl.scene.add (lines) 

You need to make sure that your scene can create lines.