Activation when objects hit to objid == 0
if(dopfield("..",$OBJID,"Impacts","Impacts",0,"otherobjid") == 0 && dopnumrecords("..",$OBJID,"Impacts","Impacts") != 0 , 1 , 0)
You can modify force_vel_to_zero inside
0 to dopoption("..", $OBJID, "Position", "velx") or $velx
0 to dopoption("..", $OBJID, "Position", "angvelx") or $angvelx