1 files changed, 175 insertions, 0 deletions

diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSActorLockAxis.cs b/OpenSim/Region/Physics/BulletSPlugin/BSActorLockAxis.cs
new file mode 100755
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--- /dev/null
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSActorLockAxis.cs
@@ -0,0 +1,175 @@
+/*
+ * Copyright (c) Contributors, http://opensimulator.org/
+ * See CONTRIBUTORS.TXT for a full list of copyright holders.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyrightD
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the OpenSimulator Project nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+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);
+        }
+    }
+}
+}