/// <summary>
/// Take the Nbody objects in the nbodies list set them inactive and make them children of a new
/// NBody object moving as the CM of the nbodies. This allows RigidBody mechanics during close
/// encounters.
/// </summary>
private void Activate()
{
if (nbodies.Length < 2)
{
Debug.LogError("Need two or more nbodies");
return;
}
GravityEngine ge = GravityEngine.Instance();
// Step 1: calculate CM position and velocity
Vector3d cmPos = new Vector3d(0, 0, 0);
Vector3d cmVel = new Vector3d(0, 0, 0);
float mass = 0f;
rigidBodies = new Rigidbody[nbodies.Length];
// RigidBody is assumed to be attached to one of the children (to keep model scale independent)
int i = 0;
foreach (NBody nbody in nbodies)
{
rigidBodies[i] = nbody.GetComponentInChildren <Rigidbody>();
//rigidBodies[i] = nbody.GetComponent<Rigidbody>();
if (rigidBodies[i] == null)
{
Debug.LogError("Abort - No rigidbody detected on " + nbody.gameObject.name);
return;
}
mass += rigidBodies[i].mass;
cmPos += rigidBodies[i].mass * ge.GetPositionDoubleV3(nbody);
cmVel += rigidBodies[i].mass * ge.GetVelocityDoubleV3(nbody);
i++;
}
cmPos /= mass;
cmVel /= mass;
Debug.LogFormat("CM p={0} v={1} mass={2}", cmPos.ToVector3(), cmVel.ToVector3(), mass);
// Step2: Inactivate the NBodies and make children of a new NBody object
priorParents = new Transform[nbodies.Length];
cmObject = new GameObject("DockingGroupCM");
cmNbody = cmObject.AddComponent <NBody>();
// Set cm pos/vel
// NBody InitPosition will use transform or initialPos base on units. Set both.
cmNbody.initialPos = cmPos.ToVector3() * ge.physToWorldFactor;
cmNbody.transform.position = cmNbody.initialPos;
ge.AddBody(cmObject);
ge.SetVelocity(cmNbody, cmVel.ToVector3());
Debug.LogFormat("set pos={0} actual={1}", cmPos.ToVector3(), ge.GetPhysicsPosition(cmNbody));
i = 0;
foreach (NBody nbody in nbodies)
{
Vector3d pos = ge.GetPositionDoubleV3(nbody);
Vector3d vel = ge.GetVelocityDoubleV3(nbody);
priorParents[i] = nbody.gameObject.transform.parent;
ge.InactivateBody(nbody.gameObject);
nbody.gameObject.transform.parent = cmObject.transform;
// position wrt to CM. Need to convert to Unity scene units from GE Internal
pos = (pos - cmPos) * ge.physToWorldFactor;
vel = GravityScaler.ScaleVelPhysToScene(vel - cmVel);
nbody.transform.localPosition = pos.ToVector3();
rigidBodies[i].velocity = vel.ToVector3();
// rigidBodies[i].isKinematic = false;
i++;
Debug.LogFormat("body {0} p={1} v={2}", nbody.gameObject.name, pos.ToVector3(), vel.ToVector3());
}
// activate any RCS elements
foreach (ReactionControlSystem r in rcs)
{
if (r != null)
{
r.SetRigidBodyEnabled(true);
}
}
}
