How to "create" a vessel

[JediMasterSterling1]

I'm fairly new in mod development, started playing around in with some code.

I want to simulate a vessels trajectory in the background, and then display it on screen. I figure an easy way to do this would be to create a vessel, read the forces on it, move it to an updated location, repeat a sufficient number of times, and delete it before the game calculates the next frame.

I figured I'd start basic and build up from there so my first test was to save the active vessel to a ProtoVessel, delete the active vessel, and reload it from the ProtoVessel

Here's the code.

ProtoVessel pv = FlightGlobals.ActiveVessel.BackupVessel();

FlightGlobals.ActiveVessel.Unload();
FlightGlobals.RemoveVessel(FlightGlobals.ActiveVessel);
FlightGlobals.ActiveVessel.StartFromBackup(pv);
FlightGlobals.ActiveVessel.Load();
FlightGlobals.AddVessel(FlightGlobals.ActiveVessel);

Unfortunately it failed miserably. I've tried several variations on this code, in case I'm just getting the order wrong, but nothing works.

I've seen mods produce new functioning vessels in game, so it should be possible.

Anyone know what I'm missing?

[wasml]

After examining the code for Hangar and ELP I managed to get the following working:

        public void LaunchEvent()
        {
            uint flightID = ShipConstruction.GetUniqueFlightID(HighLogic.CurrentGame.flightState);
            ConfigNode[] partNodes = new ConfigNode[1];
            partNodes[0] = ProtoVessel.CreatePartNode("KSI.FlareA", flightID, null);
            ConfigNode[] additionalNodes = new ConfigNode[0];
            ConfigNode protoVesselNode = ProtoVessel.CreateVesselNode("Flare", VesselType.Probe, part.vessel.GetCurrentOrbit(), 0, partNodes, additionalNodes);
            protoVesselNode.SetValue("lon", vessel.mainBody.GetLongitude(launchPoint.position));
            protoVesselNode.SetValue("lat", vessel.mainBody.GetLatitude(launchPoint.position));
            protoVesselNode.SetValue("alt", vessel.mainBody.GetAltitude(launchPoint.position));

            ProtoVessel protoVessel = HighLogic.CurrentGame.AddVessel(protoVesselNode);

            flare = protoVessel.vesselRef;
            if (flare != null)
            {
                flare.Load();
                StartCoroutine("Spawn");
            }
        }

        IEnumerator Spawn()
        {
            if ((flare.Parts[0] != null) && (flare.Parts[0].Rigidbody != null))
            {
                flare.Parts[0].Rigidbody.isKinematic = true;
            }

            while ((flare.packed) && (flare.acceleration.magnitude == 0))
            {
                flare.SetPosition(launchPoint.position);
                yield return null;
            }
            flare.SetWorldVelocity(launchPoint.up * velocity);

            flare.GoOffRails();
            flare.IgnoreGForces(250);
        }

This would create a vessel from a part named "KSI.FlareA".

Notes: 1) this is a single part that gets created as a vessel 2) some of the lines may not be needed - got here by trial and error (lots of error) 3) it wasn't crashing the game but I didn't leave the game up very long - use at your own risk!