Autodesk Forge Viewer transform 2D to 3D coordinates - autodesk

Question

I am testing the possibilities of the forge V7 viewer on a web browser with a revit model.
The idea of ​​the test is:
display 2 viewers simultaneously with 1 3D view and a 2D view
click on a point of the 2D view and
display a sphere in the 2D view on this point
display another sphere in the 3D view at the equivalent point
the spheres are added with SceneBuilder (to allow them to be selected later)
I tried to follow the behavior of
https://forge.autodesk.com/ja/node/1765 and
https://github.com/Autodesk-Forge/viewer-navigation.sample
and i have questions
1 - the 2D view must be a sheet, using a 2D view directly (a floor view for example) does not allow the calculation, is that correct?
2 - https://forge.autodesk.com/ja/node/1765 seems to have calculation and/or precision issues (cf forge1.png generated from the test in Heroku and forge2.png generated by my program)
3 - the method only works if you click on an object
how can I retrieve the coordinates if I click in an empty area?
4 - the spheres are identified in the viewer (cf forge3.png), but
a - how to give them a name (and not "object")
b - how to replace the name "model" by the name of the scene?
Can you help me ?
Thanks in advance
Luc
Here is my code
// click listener on 2d viewer
function listenerScene(ev){
var intersection = viewer2d.hitTest(ev.offsetX, ev.offsetY);
if (intersection) {
AddItem(intersection.intersectPoint.x, intersection.intersectPoint.y,
intersection.intersectPoint.z);
AddItem3d(intersection);
}
// add in 2d
async function AddItem(x,y,z){
... add a sphere at (x,y,z)
}
// add in 3d
async function AddItem3d(intersection) {
const worldPos = sheetToWorld(intersection.intersectPoint,
viewer2d.model,viewer.model);
if (worldPos) {
... add a sphere at worldPos
}
}
// compute 3d point
function sheetToWorld(sheetPos, model2d, model3d) {
const viewportExt = viewer2d.getExtension('Autodesk.AEC.ViewportsExtension');
const viewport = viewportExt.findViewportAtPoint(model2d, new THREE.Vector2(sheetPos.x, sheetPos.y));
if (!viewport) {
return null;
}
const sheetUnitScale = model2d.getUnitScale();
const globalOffset = model3d.getData().globalOffset;
const matrix = viewport.get2DTo3DMatrix(sheetUnitScale);
var worldPos = sheetPos.clone().applyMatrix4(matrix);
worldPos = worldPos.sub(globalOffset);
return worldPos;
}