OpenSimMirror/OpenSim/Region/Physics/BulletSPlugin/BSActorLockAxis.cs

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

using OMV = OpenMetaverse;

namespace OpenSim.Region.Physics.BulletSPlugin
{
public class BSActorLockAxis : BSActor
{
    BSConstraint LockAxisConstraint = null;

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

    // BSActor.isActive
    public override bool isActive
    {
        get { return Enabled && m_controllingPrim.IsPhysicallyActive; }
    }

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

    // 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},BSActorLockAxis,refresh,lockedAxis={1},enabled={2},pActive={3}",
                                    m_controllingPrim.LocalID, m_controllingPrim.LockedAngularAxis, Enabled, m_controllingPrim.IsPhysicallyActive);
        // If all the axis are free, we don't need to exist
        if (m_controllingPrim.LockedAngularAxis == m_controllingPrim.LockedAxisFree)
        {
            Enabled = false;
        }

        // If the object is physically active, add the axis locking constraint
        if (isActive)
        {
            AddAxisLockConstraint();
        }
        else
        {
            RemoveAxisLockConstraint();
        }
    }

    // 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()
    {
        if (LockAxisConstraint != null)
        {
            // If a constraint is set up, remove it from the physical scene
            RemoveAxisLockConstraint();
            // Schedule a call before the next simulation step to restore the constraint.
            m_physicsScene.PostTaintObject("BSActorLockAxis:" + ActorName, m_controllingPrim.LocalID, delegate()
            {
                Refresh();
            });
        }
    }

    private void AddAxisLockConstraint()
    {
        if (LockAxisConstraint == null)
        {
            // Lock that axis by creating a 6DOF constraint that has one end in the world and
            //    the other in the object.
            // http://www.bulletphysics.org/Bullet/phpBB3/viewtopic.php?p=20817
            // http://www.bulletphysics.org/Bullet/phpBB3/viewtopic.php?p=26380

            // Remove any existing axis constraint (just to be sure)
            RemoveAxisLockConstraint();

            BSConstraint6Dof axisConstrainer = new BSConstraint6Dof(m_physicsScene.World, m_controllingPrim.PhysBody,
                                OMV.Vector3.Zero, OMV.Quaternion.Identity,
                                false /* useLinearReferenceFrameB */, true /* disableCollisionsBetweenLinkedBodies */);
            LockAxisConstraint = axisConstrainer;
            m_physicsScene.Constraints.AddConstraint(LockAxisConstraint);

            // The constraint is tied to the world and oriented to the prim.

            // Free to move linearly in the region
            OMV.Vector3 linearLow = OMV.Vector3.Zero;
            OMV.Vector3 linearHigh = m_physicsScene.TerrainManager.DefaultRegionSize;
            if (m_controllingPrim.LockedLinearAxis.X != BSPhysObject.FreeAxis)
            {
                linearLow.X = m_controllingPrim.RawPosition.X;
                linearHigh.X = m_controllingPrim.RawPosition.X;
            }
            if (m_controllingPrim.LockedLinearAxis.Y != BSPhysObject.FreeAxis)
            {
                linearLow.Y = m_controllingPrim.RawPosition.Y;
                linearHigh.Y = m_controllingPrim.RawPosition.Y;
            }
            if (m_controllingPrim.LockedLinearAxis.Z != BSPhysObject.FreeAxis)
            {
                linearLow.Z = m_controllingPrim.RawPosition.Z;
                linearHigh.Z = m_controllingPrim.RawPosition.Z;
            }
            axisConstrainer.SetLinearLimits(linearLow, linearHigh);

            // Angular with some axis locked
            float fPI = (float)Math.PI;
            OMV.Vector3 angularLow = new OMV.Vector3(-fPI, -fPI, -fPI);
            OMV.Vector3 angularHigh = new OMV.Vector3(fPI, fPI, fPI);
            if (m_controllingPrim.LockedAngularAxis.X != BSPhysObject.FreeAxis)
            {
                angularLow.X = 0f;
                angularHigh.X = 0f;
            }
            if (m_controllingPrim.LockedAngularAxis.Y != BSPhysObject.FreeAxis)
            {
                angularLow.Y = 0f;
                angularHigh.Y = 0f;
            }
            if (m_controllingPrim.LockedAngularAxis.Z != BSPhysObject.FreeAxis)
            {
                angularLow.Z = 0f;
                angularHigh.Z = 0f;
            }
            if (!axisConstrainer.SetAngularLimits(angularLow, angularHigh))
            {
                m_physicsScene.DetailLog("{0},BSActorLockAxis.AddAxisLockConstraint,failedSetAngularLimits", m_controllingPrim.LocalID);
            }

            m_physicsScene.DetailLog("{0},BSActorLockAxis.AddAxisLockConstraint,create,linLow={1},linHi={2},angLow={3},angHi={4}",
                                        m_controllingPrim.LocalID, linearLow, linearHigh, angularLow, angularHigh);

            // Constants from one of the posts mentioned above and used in Bullet's ConstraintDemo.
            axisConstrainer.TranslationalLimitMotor(true /* enable */, 5.0f, 0.1f);

            axisConstrainer.RecomputeConstraintVariables(m_controllingPrim.RawMass);
        }
    }

    private void RemoveAxisLockConstraint()
    {
        if (LockAxisConstraint != null)
        {
            m_physicsScene.Constraints.RemoveAndDestroyConstraint(LockAxisConstraint);
            LockAxisConstraint = null;
            m_physicsScene.DetailLog("{0},BSActorLockAxis.RemoveAxisLockConstraint,destroyingConstraint", m_controllingPrim.LocalID);
        }
    }
}
}