This works
_obj = _this select 0
_PosObject = getPos _obj
_PosTarget = getpos ah
_velocity = 1000
_distance = _obj distance ah
trigPos setPos _PosObject
_z1sea = trigPos distance _obj
trigPos setPos _PosTarget
_z2sea = trigPos distance ah
_x1 = (_PosObject select 0)
_y1 = (_PosObject select 1)
_z1 = (_PosObject select 2)
_x2 = (_PosTarget select 0)
_y2 = (_PosTarget select 1)
_z2 =(_PosTarget select 2)
_Coef = _velocity/_distance
_xcomponent = (_x2 - _x1)
_ycomponent = (_y2 -_y1)
_zcomponent = (_z2+_z2sea) -(_z1 + _z1sea )
_xvector = _xcomponent * _coef
_yvector =_Ycomponent * _coef
_zvector = _zcomponent * _coef
player globalchat format ["z1sea %1 z2sea %2 z1 %3 z2 %4",_z1sea, _z2sea ,_z1, _z2 ]
_lifetime = _distance/_velocity
_weight = 1
_Volume = 0.155 * 0.2 *0.155
_Densite =7.85
drop ["cl_fire", "" , "Billboard", 10, _lifetime, _PosObject , [_xvector ,_yvector ,_zvector ], 0, _weight, _Volume , 0, [_weight,_Volume], [[1,1,0,1], [1, 1, 0, 1]],
- , 0, 0, "", "sparks.sqs",""]
Thx Dinger