opensim/OpenSim/Region/PhysicsModules/BulletS/BSActorMoveToTarget.cs

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using OpenSim.Region.PhysicsModules.SharedBase;

using OMV = OpenMetaverse;

namespace OpenSim.Region.PhysicsModule.BulletS
{
    public class BSActorMoveToTarget : BSActor
    {
        private BSVMotor m_targetMotor;

        public BSActorMoveToTarget(BSScene physicsScene, BSPhysObject pObj, string actorName)
            : base(physicsScene, pObj, actorName)
        {
            m_targetMotor = null;
            m_physicsScene.DetailLog("{0},BSActorMoveToTarget,constructor", m_controllingPrim.LocalID);
        }

        // BSActor.isActive
        public override bool isActive
        {
            // MoveToTarget only works on physical prims
            get { return Enabled && m_controllingPrim.IsPhysicallyActive; }
        }

        // Release any connections and resources used by the actor.
        // BSActor.Dispose()
        public override void Dispose()
        {
            Enabled = false;
            DeactivateMoveToTarget();
        }

        // Called when physical parameters (properties set in Bullet) need to be re-applied.
        // Called at taint-time.
        // BSActor.Refresh()
        public override void Refresh()
        {
            m_physicsScene.DetailLog("{0},BSActorMoveToTarget,refresh,enabled={1},active={2},target={3},tau={4}",
                m_controllingPrim.LocalID, Enabled, m_controllingPrim.MoveToTargetActive,
                m_controllingPrim.MoveToTargetTarget, m_controllingPrim.MoveToTargetTau );

            // If not active any more...
            if (!m_controllingPrim.MoveToTargetActive)
            {
                Enabled = false;
            }

            if (isActive)
            {
                ActivateMoveToTarget();
            }
            else
            {
                DeactivateMoveToTarget();
            }
        }

        // The object's physical representation is being rebuilt so pick up any physical dependencies (constraints, ...).
        //     Register a prestep action to restore physical requirements before the next simulation step.
        // Called at taint-time.
        // BSActor.RemoveDependencies()
        public override void RemoveDependencies()
        {
            // Nothing to do for the moveToTarget since it is all software at pre-step action time.
        }

        // If a hover motor has not been created, create one and start the hovering.
        private void ActivateMoveToTarget()
        {
            if (m_targetMotor == null)
            {
                // We're taking over after this.
                m_controllingPrim.ZeroMotion(true);

                /* Someday use the PID controller
                m_targetMotor = new BSPIDVMotor("BSActorMoveToTarget-" + m_controllingPrim.LocalID.ToString());
                m_targetMotor.TimeScale = m_controllingPrim.MoveToTargetTau;
                m_targetMotor.Efficiency = 1f;
                 */
                m_targetMotor = new BSVMotor("BSActorMoveToTarget-" + m_controllingPrim.LocalID.ToString(),
                                            m_controllingPrim.MoveToTargetTau,  // timeScale
                                            BSMotor.Infinite,                   // decay time scale
                                            1f                                  // efficiency
                );
                m_targetMotor.PhysicsScene = m_physicsScene; // DEBUG DEBUG so motor will output detail log messages.
                m_targetMotor.SetTarget(m_controllingPrim.MoveToTargetTarget);
                m_targetMotor.SetCurrent(m_controllingPrim.RawPosition);

                // m_physicsScene.BeforeStep += Mover;
                m_physicsScene.BeforeStep += Mover2;
            }
            else
            {
                // If already allocated, make sure the target and other paramters are current
                m_targetMotor.SetTarget(m_controllingPrim.MoveToTargetTarget);
                m_targetMotor.SetCurrent(m_controllingPrim.RawPosition);
            }
        }

        private void DeactivateMoveToTarget()
        {
            if (m_targetMotor != null)
            {
                // m_physicsScene.BeforeStep -= Mover;
                m_physicsScene.BeforeStep -= Mover2;
                m_targetMotor = null;
            }
        }

        // Origional mover that set the objects position to move to the target.
        // The problem was that gravity would keep trying to push the object down so
        //    the overall downward velocity would increase to infinity.
        // Called just before the simulation step.
        private void Mover(float timeStep)
        {
            // Don't do hovering while the object is selected.
            if (!isActive)
                return;

            OMV.Vector3 origPosition = m_controllingPrim.RawPosition;     // DEBUG DEBUG (for printout below)

            // 'movePosition' is where we'd like the prim to be at this moment.
            OMV.Vector3 movePosition = m_controllingPrim.RawPosition + m_targetMotor.Step(timeStep);

            // If we are very close to our target, turn off the movement motor.
            if (m_targetMotor.ErrorIsZero())
            {
                m_physicsScene.DetailLog("{0},BSActorMoveToTarget.Mover,zeroMovement,movePos={1},pos={2},mass={3}",
                                        m_controllingPrim.LocalID, movePosition, m_controllingPrim.RawPosition, m_controllingPrim.Mass);
                m_controllingPrim.ForcePosition = m_targetMotor.TargetValue;
                m_controllingPrim.ForceVelocity = OMV.Vector3.Zero;
                // Setting the position does not cause the physics engine to generate a property update. Force it.
                m_physicsScene.PE.PushUpdate(m_controllingPrim.PhysBody);
            }
            else
            {
                m_controllingPrim.ForcePosition = movePosition;
                // Setting the position does not cause the physics engine to generate a property update. Force it.
                m_physicsScene.PE.PushUpdate(m_controllingPrim.PhysBody);
            }
            m_physicsScene.DetailLog("{0},BSActorMoveToTarget.Mover,move,fromPos={1},movePos={2}",
                                            m_controllingPrim.LocalID, origPosition, movePosition);
        }

        // Version of mover that applies forces to move the physical object to the target.
        // Also overcomes gravity so the object doesn't just drop to the ground.
        // Called just before the simulation step.
        private void Mover2(float timeStep)
        {
            // Don't do hovering while the object is selected.
            if (!isActive)
                return;

            OMV.Vector3 origPosition = m_controllingPrim.RawPosition;     // DEBUG DEBUG (for printout below)
            OMV.Vector3 addedForce = OMV.Vector3.Zero;

            // CorrectionVector is the movement vector required this step
            OMV.Vector3 correctionVector = m_targetMotor.Step(timeStep, m_controllingPrim.RawPosition);

            // If we are very close to our target, turn off the movement motor.
            if (m_targetMotor.ErrorIsZero())
            {
                m_physicsScene.DetailLog("{0},BSActorMoveToTarget.Mover3,zeroMovement,pos={1},mass={2}",
                                        m_controllingPrim.LocalID, m_controllingPrim.RawPosition, m_controllingPrim.Mass);
                m_controllingPrim.ForcePosition = m_targetMotor.TargetValue;
                m_controllingPrim.ForceVelocity = OMV.Vector3.Zero;
                // Setting the position does not cause the physics engine to generate a property update. Force it.
                m_physicsScene.PE.PushUpdate(m_controllingPrim.PhysBody);
            }
            else
            {
                // First force to move us there -- the motor return a timestep scaled value.
                addedForce = correctionVector / timeStep;
                // Remove the existing velocity (only the moveToTarget force counts)
                addedForce -= m_controllingPrim.RawVelocity;
                // Overcome gravity.
                addedForce -= m_controllingPrim.Gravity;

                // Add enough force to overcome the mass of the object
                addedForce *= m_controllingPrim.Mass;

                m_controllingPrim.AddForce(true /* inTaintTime */, addedForce);
            }
            m_physicsScene.DetailLog("{0},BSActorMoveToTarget.Mover3,move,fromPos={1},addedForce={2}",
                                            m_controllingPrim.LocalID, origPosition, addedForce);
        }
    }
}