How to know the ElementIndex when hitting on an obj

I got a mesh which has 6 materials, now i want to use mouse click on it to finger out which material i choose ,how can i do to get the element index of the material, please help,thanks a lot

That’s not currently possible. Traces and collisions are made against collision shapes, which are usually different than the rendering mesh and don’t have material information.

So the alternatives are :

  1. Break the mesh into multiple objects with one material each
  2. Read the “Hit Item” index from the trace’s “Hit” result, which will tell the index of the collision shape that was hit and hardcode the corresponding materials
  3. Manually add collision boxes to your actor and make each one change a different material in your mesh

Seems the first way is easier for me… ,BTW i don’t know why the ‘HTI Item’ has always been “-1” wherever i click on,and can i hardcode that by blueprint?which node?thanks again

mine FaceIndex is always -1 as well.