Getting bounding boxes of each component in the viewer

By Philippe Leefsma

Accessing the bounding box is a pretty straightforward thing to do from a standard Three.js model:

var bb = mesh.geometry.boundingBox

However optimisations in our custom renderer makes it a little bit less intuitive. Below are two snippets that illustrate how to compute bounding box for the selected component. Typically when you select a component visually, the Autodesk.Viewing.SELECTION_CHANGED_EVENT returns an object that contains the list of fragmentIds, which you need to pass to those methods (see full sample further down):

 1 //returns bounding box as it appears in the viewer
 2 // (transformations could be applied)
 3 function getModifiedWorldBoundingBox(fragIds, fragList) {
 4 
 5     var fragbBox = new THREE.Box3();
 6     var nodebBox = new THREE.Box3();
 7 
 8     fragIds.forEach(function(fragId) {
 9 
10         fragList.getWorldBounds(fragId, fragbBox);
11         nodebBox.union(fragbBox);
12     });
13 
14     return nodebBox;
15 }
16 
17 // Returns bounding box as loaded in the file
18 // (no explosion nor transformation)
19 function getOriginalWorldBoundingBox(fragIds, fragList) {
20 
21     var fragBoundingBox = new THREE.Box3();
22     var nodeBoundingBox = new THREE.Box3();
23 
24     var fragmentBoxes = fragList.boxes;
25 
26     fragIds.forEach(function(fragId) {
27 
28         var boffset = fragId * 6;
29 
30         fragBoundingBox.min.x = fragmentBoxes[boffset];
31         fragBoundingBox.min.y = fragmentBoxes[boffset+1];
32         fragBoundingBox.min.z = fragmentBoxes[boffset+2];
33         fragBoundingBox.max.x = fragmentBoxes[boffset+3];
34         fragBoundingBox.max.y = fragmentBoxes[boffset+4];
35         fragBoundingBox.max.z = fragmentBoxes[boffset+5];
36 
37         nodeBoundingBox.union(fragBoundingBox);
38     });
39 
40     return nodeBoundingBox;
41 }

Here is the result of the extension code provided below. You can test a live version here: