414 lines
16 KiB
C#
Executable File
414 lines
16 KiB
C#
Executable File
/*
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* Copyright (c) Contributors, http://opensimulator.org/
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* See CONTRIBUTORS.TXT for a full list of copyright holders.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyrightD
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the OpenSimulator Project nor the
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* names of its contributors may be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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using System;
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using System.Collections.Generic;
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using System.Text;
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using OMV = OpenMetaverse;
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namespace OpenSim.Region.Physics.BulletSPlugin
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{
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public class BSLinkset
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{
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private static string LogHeader = "[BULLETSIM LINKSET]";
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private BSPrim m_linksetRoot;
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public BSPrim LinksetRoot { get { return m_linksetRoot; } }
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private BSScene m_physicsScene;
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public BSScene PhysicsScene { get { return m_physicsScene; } }
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static int m_nextLinksetID = 1;
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public int LinksetID { get; private set; }
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// The children under the root in this linkset
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private List<BSPrim> m_children;
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// We lock the diddling of linkset classes to prevent any badness.
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// This locks the modification of the instances of this class. Changes
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// to the physical representation is done via the tainting mechenism.
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private object m_linksetActivityLock = new Object();
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// We keep the prim's mass in the linkset structure since it could be dependent on other prims
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private float m_mass;
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public float LinksetMass
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{
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get
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{
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m_mass = ComputeLinksetMass();
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return m_mass;
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}
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}
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public OMV.Vector3 CenterOfMass
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{
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get { return ComputeLinksetCenterOfMass(); }
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}
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public OMV.Vector3 GeometricCenter
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{
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get { return ComputeLinksetGeometricCenter(); }
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}
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public BSLinkset(BSScene scene, BSPrim parent)
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{
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// A simple linkset of one (no children)
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LinksetID = m_nextLinksetID++;
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// We create LOTS of linksets.
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if (m_nextLinksetID < 0)
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m_nextLinksetID = 1;
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m_physicsScene = scene;
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m_linksetRoot = parent;
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m_children = new List<BSPrim>();
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m_mass = parent.MassRaw;
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}
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// Link to a linkset where the child knows the parent.
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// Parent changing should not happen so do some sanity checking.
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// We return the parent's linkset so the child can track its membership.
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public BSLinkset AddMeToLinkset(BSPrim child)
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{
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lock (m_linksetActivityLock)
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{
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AddChildToLinkset(child);
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}
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return this;
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}
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// Remove a child from a linkset.
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// Returns a new linkset for the child which is a linkset of one (just the
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// orphened child).
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public BSLinkset RemoveMeFromLinkset(BSPrim child)
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{
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lock (m_linksetActivityLock)
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{
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if (IsRoot(child))
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{
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// if root of linkset, take the linkset apart
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while (m_children.Count > 0)
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{
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// Note that we don't do a foreach because the remove routine
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// takes it out of the list.
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RemoveChildFromOtherLinkset(m_children[0]);
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}
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m_children.Clear(); // just to make sure
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}
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else
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{
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// Just removing a child from an existing linkset
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RemoveChildFromLinkset(child);
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}
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}
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// The child is down to a linkset of just itself
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return new BSLinkset(PhysicsScene, child);
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}
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// Return 'true' if the passed object is the root object of this linkset
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public bool IsRoot(BSPrim requestor)
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{
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return (requestor.LocalID == m_linksetRoot.LocalID);
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}
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public int NumberOfChildren { get { return m_children.Count; } }
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// Return 'true' if this linkset has any children (more than the root member)
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public bool HasAnyChildren { get { return (m_children.Count > 0); } }
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// Return 'true' if this child is in this linkset
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public bool HasChild(BSPrim child)
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{
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bool ret = false;
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lock (m_linksetActivityLock)
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{
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foreach (BSPrim bp in m_children)
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{
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if (child.LocalID == bp.LocalID)
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{
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ret = true;
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break;
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}
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}
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}
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return ret;
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}
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private float ComputeLinksetMass()
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{
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float mass = m_linksetRoot.MassRaw;
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foreach (BSPrim bp in m_children)
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{
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mass += bp.MassRaw;
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}
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return mass;
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}
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private OMV.Vector3 ComputeLinksetCenterOfMass()
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{
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OMV.Vector3 com = m_linksetRoot.Position * m_linksetRoot.MassRaw;
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float totalMass = m_linksetRoot.MassRaw;
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lock (m_linksetActivityLock)
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{
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foreach (BSPrim bp in m_children)
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{
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com += bp.Position * bp.MassRaw;
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totalMass += bp.MassRaw;
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}
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if (totalMass != 0f)
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com /= totalMass;
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}
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return com;
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}
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private OMV.Vector3 ComputeLinksetGeometricCenter()
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{
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OMV.Vector3 com = m_linksetRoot.Position;
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lock (m_linksetActivityLock)
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{
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foreach (BSPrim bp in m_children)
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{
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com += bp.Position * bp.MassRaw;
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}
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com /= (m_children.Count + 1);
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}
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return com;
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}
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// When physical properties are changed the linkset needs to recalculate
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// its internal properties.
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public void Refresh(BSPrim requestor)
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{
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// If there are no children, there aren't any constraints to recompute
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if (!HasAnyChildren)
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return;
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// Only the root does the recomputation
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if (IsRoot(requestor))
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{
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PhysicsScene.TaintedObject("BSLinkSet.Refresh", delegate()
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{
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RecomputeLinksetConstraintVariables();
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});
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}
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}
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// Call each of the constraints that make up this linkset and recompute the
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// various transforms and variables. Used when objects are added or removed
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// from a linkset to make sure the constraints know about the new mass and
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// geometry.
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// Must only be called at taint time!!
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private bool RecomputeLinksetConstraintVariables()
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{
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float linksetMass = LinksetMass;
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lock (m_linksetActivityLock)
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{
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foreach (BSPrim child in m_children)
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{
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BSConstraint constrain;
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if (m_physicsScene.Constraints.TryGetConstraint(LinksetRoot.Body, child.Body, out constrain))
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{
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// DetailLog("{0},BSLinkset.RecomputeLinksetConstraintVariables,taint,child={1},mass={2},A={3},B={4}",
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// LinksetRoot.LocalID, child.LocalID, linksetMass, constrain.Body1.ID, constrain.Body2.ID);
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constrain.RecomputeConstraintVariables(linksetMass);
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}
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else
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{
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// Non-fatal error that can happen when children are being added to the linkset but
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// their constraints have not been created yet.
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// Caused by the fact that m_children is built at run time but building constraints
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// happens at taint time.
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// m_physicsScene.Logger.ErrorFormat("[BULLETSIM LINKSET] RecomputeLinksetConstraintVariables: constraint not found for root={0}, child={1}",
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// m_linksetRoot.Body.ID, child.Body.ID);
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}
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}
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}
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return false;
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}
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// I am the root of a linkset and a new child is being added
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// Called while LinkActivity is locked.
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private void AddChildToLinkset(BSPrim child)
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{
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if (!HasChild(child))
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{
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m_children.Add(child);
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BSPrim rootx = LinksetRoot; // capture the root as of now
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BSPrim childx = child;
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m_physicsScene.TaintedObject("AddChildToLinkset", delegate()
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{
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DetailLog("{0},AddChildToLinkset,taint,child={1}", m_linksetRoot.LocalID, child.LocalID);
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PhysicallyLinkAChildToRoot(rootx, childx); // build the physical binding between me and the child
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});
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}
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return;
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}
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// Forcefully removing a child from a linkset.
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// This is not being called by the child so we have to make sure the child doesn't think
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// it's still connected to the linkset.
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// Normal OpenSimulator operation will never do this because other SceneObjectPart information
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// has to be updated also (like pointer to prim's parent).
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private void RemoveChildFromOtherLinkset(BSPrim pchild)
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{
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pchild.Linkset = new BSLinkset(m_physicsScene, pchild);
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RemoveChildFromLinkset(pchild);
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}
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// I am the root of a linkset and one of my children is being removed.
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// Safe to call even if the child is not really in my linkset.
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private void RemoveChildFromLinkset(BSPrim child)
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{
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if (m_children.Remove(child))
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{
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BSPrim rootx = LinksetRoot; // capture the root as of now
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BSPrim childx = child;
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m_physicsScene.TaintedObject("RemoveChildFromLinkset", delegate()
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{
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DetailLog("{0},RemoveChildFromLinkset,taint,child={1}", m_linksetRoot.LocalID, child.LocalID);
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PhysicallyUnlinkAChildFromRoot(rootx, childx);
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});
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RecomputeLinksetConstraintVariables();
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}
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else
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{
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// This will happen if we remove the root of the linkset first. Non-fatal occurance.
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// PhysicsScene.Logger.ErrorFormat("{0}: Asked to remove child from linkset that was not in linkset", LogHeader);
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}
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return;
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}
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// Create a constraint between me (root of linkset) and the passed prim (the child).
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// Called at taint time!
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private void PhysicallyLinkAChildToRoot(BSPrim rootPrim, BSPrim childPrim)
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{
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// Zero motion for children so they don't interpolate
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childPrim.ZeroMotion();
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// Relative position normalized to the root prim
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// Essentually a vector pointing from center of rootPrim to center of childPrim
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OMV.Vector3 childRelativePosition = childPrim.Position - rootPrim.Position;
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// real world coordinate of midpoint between the two objects
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OMV.Vector3 midPoint = rootPrim.Position + (childRelativePosition / 2);
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// create a constraint that allows no freedom of movement between the two objects
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// http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?t=4818
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DetailLog("{0},PhysicallyLinkAChildToRoot,taint,root={1},child={2},rLoc={3},cLoc={4},midLoc={5}",
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rootPrim.LocalID, rootPrim.LocalID, childPrim.LocalID, rootPrim.Position, childPrim.Position, midPoint);
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BS6DofConstraint constrain = new BS6DofConstraint(
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m_physicsScene.World, rootPrim.Body, childPrim.Body,
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midPoint,
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true,
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true
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);
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/* NOTE: below is an attempt to build constraint with full frame computation, etc.
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* Using the midpoint is easier since it lets the Bullet code use the transforms
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* of the objects.
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* Code left as a warning to future programmers.
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// ==================================================================================
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// relative position normalized to the root prim
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OMV.Quaternion invThisOrientation = OMV.Quaternion.Inverse(rootPrim.Orientation);
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OMV.Vector3 childRelativePosition = (childPrim.Position - rootPrim.Position) * invThisOrientation;
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// relative rotation of the child to the parent
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OMV.Quaternion childRelativeRotation = invThisOrientation * childPrim.Orientation;
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OMV.Quaternion inverseChildRelativeRotation = OMV.Quaternion.Inverse(childRelativeRotation);
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// create a constraint that allows no freedom of movement between the two objects
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// http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?t=4818
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DetailLog("{0},PhysicallyLinkAChildToRoot,taint,root={1},child={2}", rootPrim.LocalID, rootPrim.LocalID, childPrim.LocalID);
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BS6DofConstraint constrain = new BS6DofConstraint(
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PhysicsScene.World, rootPrim.Body, childPrim.Body,
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OMV.Vector3.Zero,
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OMV.Quaternion.Inverse(rootPrim.Orientation),
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OMV.Vector3.Zero,
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OMV.Quaternion.Inverse(childPrim.Orientation),
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// A point half way between the parent and child
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// childRelativePosition/2,
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// childRelativeRotation,
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// childRelativePosition/2,
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// inverseChildRelativeRotation,
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true,
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true
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);
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// ==================================================================================
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*/
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m_physicsScene.Constraints.AddConstraint(constrain);
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// zero linear and angular limits makes the objects unable to move in relation to each other
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constrain.SetLinearLimits(OMV.Vector3.Zero, OMV.Vector3.Zero);
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constrain.SetAngularLimits(OMV.Vector3.Zero, OMV.Vector3.Zero);
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// tweek the constraint to increase stability
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constrain.UseFrameOffset(PhysicsScene.BoolNumeric(PhysicsScene.Params.linkConstraintUseFrameOffset));
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constrain.TranslationalLimitMotor(PhysicsScene.BoolNumeric(PhysicsScene.Params.linkConstraintEnableTransMotor),
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PhysicsScene.Params.linkConstraintTransMotorMaxVel,
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PhysicsScene.Params.linkConstraintTransMotorMaxForce);
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constrain.SetCFMAndERP(PhysicsScene.Params.linkConstraintCFM, PhysicsScene.Params.linkConstraintERP);
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RecomputeLinksetConstraintVariables();
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}
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// Remove linkage between myself and a particular child
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// Called at taint time!
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private void PhysicallyUnlinkAChildFromRoot(BSPrim rootPrim, BSPrim childPrim)
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{
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DetailLog("{0},PhysicallyUnlinkAChildFromRoot,taint,root={1},child={2}", rootPrim.LocalID, rootPrim.LocalID, childPrim.LocalID);
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// Find the constraint for this link and get rid of it from the overall collection and from my list
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m_physicsScene.Constraints.RemoveAndDestroyConstraint(rootPrim.Body, childPrim.Body);
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// Make the child refresh its location
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BulletSimAPI.PushUpdate2(childPrim.Body.Ptr);
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}
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// Remove linkage between myself and any possible children I might have
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// Called at taint time!
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private void PhysicallyUnlinkAllChildrenFromRoot(BSPrim rootPrim)
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{
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DetailLog("{0},PhysicallyUnlinkAllChildren,taint", rootPrim.LocalID);
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m_physicsScene.Constraints.RemoveAndDestroyConstraint(rootPrim.Body);
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}
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// Invoke the detailed logger and output something if it's enabled.
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private void DetailLog(string msg, params Object[] args)
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{
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m_physicsScene.PhysicsLogging.Write(msg, args);
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}
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}
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}
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