How To Emit a Particle

#1 When the user clicks, do a raycast and see if the magic box got hit. If so, trigger the emitter that's mounted to the box.

For the clicking, bind a button click to a script function that triggers the raycast.

For the raycast, use GuiCanvas::getCursorPosition (you probably need to translate from true screen-space coordinates to window-space coordinates using GuiCanvas::screenToClient) and GuiTSCtrl::unproject to project the current mouse cursor to world-space coordinates. Then subtract that vector from the camera position, turn that vector into a unit vector, multiply it by the distance by which you want to cast, and then add it to the camera position to get the position of the raycast endpoint.

Then do a containerRayCast and see if your magic box got hit.

For any other kind of picking that you need, you can the simply extend the processing of the raycast result.

Word of caution, though... I suck at math so the vector math here may be faulty plus there may be a much simpler way to do this that I'm totally overlooking.

#2 Thank you Rene Damm You answered Help me. Thank You...