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 *       derived from this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
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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
{
    bool TryExperimentalLockAxisCode = true;
    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.LockedAxis, Enabled, m_controllingPrim.IsPhysicallyActive);
        // If all the axis are free, we don't need to exist
        if (m_controllingPrim.LockedAxis == m_controllingPrim.LockedAxisFree)
        {
            m_physicsScene.DetailLog("{0},BSActorLockAxis,refresh,allAxisFree,removing={1}", m_controllingPrim.LocalID, ActorName);
            m_controllingPrim.PhysicalActors.RemoveAndRelease(ActorName);
            return;
        }
        // If the object is physically active, add the axis locking constraint
        if (Enabled
                && m_controllingPrim.IsPhysicallyActive
                && TryExperimentalLockAxisCode
                && m_controllingPrim.LockedAxis != m_controllingPrim.LockedAxisFree)
        {
            if (LockAxisConstraint == null)
                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.RemoveBodyDependencies()
    public override void RemoveBodyDependencies()
    {
        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(m_controllingPrim.LockedAxisActorName, m_controllingPrim.LocalID, delegate()
            {
                Refresh();
            });
        }
    }

    private void AddAxisLockConstraint()
    {
        // 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;
        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.LockedAxis.X != 1f)
        {
            angularLow.X = 0f;
            angularHigh.X = 0f;
        }
        if (m_controllingPrim.LockedAxis.Y != 1f)
        {
            angularLow.Y = 0f;
            angularHigh.Y = 0f;
        }
        if (m_controllingPrim.LockedAxis.Z != 1f)
        {
            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);
        }
    }
}
}