about softbody Collision

[josemendez]

I make a ground and a control softbody in scene . when the sofybody collision with the ground,this first collision

It’s not entirely clear to me, sorry. First collision since when? in the game? since last time the ground and the softbody where in contact? First particle that contacts the ground? First contact reported in the list of contacts for a single frame?

An object might collide with another during a single frame, or multiple frames.
You can get all contacts for the current frame using the collision callbacks API, see the link above. You can simply subscribe to the OnCollision event and grab the first contact in the list, if that’s what you are after.