Forge Autodesk model's transform matrix

Question

I would like to know what are the two matrix below and what they are used for :

• placementTransform (1 x 12)
• refPointTransform (1 x 16)

Does anyone know what they are used ? I think it has to do with translation(Tx, Ty, Tz)/rotation (Rx, Ry, Rz) of 3D objects but there are too many parameters in each vector...

Answer 1

The placementTransform sets the position-offset and scale of a model during loading. refPointTransform is similar (but contains rotation), but is applied (multiplied) after the placementTransform.

Here is an example and source code, of how to use 'placementTransform': https://github.com/wallabyway/viewer-multimodel-search/blob/1c2e71397a78ab807644f96dfb34b8e578825987/docs/index.html#L61

Take a look at line 61. When I load in the second model, I set the offset and scale of the 3D-building, so that it's positioned above the 3D-hand-saw.