I'm making a short skit, and in one of the scenes a girl falls through a hidden trap door into a long chute. When I tried to create this effect I took a picture of the room, making sure to fully capture the area where I wanted the trap door to be. Then I went on hitfilm and started editing. I decided to work backward, first using a mask to warp a section of the floor to make in look like the floor fell. I inserted a picture a a long chute under this, and it actually looked like the floor opened. But when I tried to keyframe it to make the floor move back up and cover up the gap, making the floor whole, I couldn't get the floor to look like it was actually a trap door opening and closing. Any tips?