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1/*
2 * Copyright (c) Contributors, http://opensimulator.org/
3 * See CONTRIBUTORS.TXT for a full list of copyright holders.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 * * Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * * Redistributions in binary form must reproduce the above copyrightD
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * * Neither the name of the OpenSimulator Project nor the
13 * names of its contributors may be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
17 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
20 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
23 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27using System;
28using System.Collections.Generic;
29using System.Text;
30
31using OMV = OpenMetaverse;
32
33namespace OpenSim.Region.Physics.BulletSPlugin
34{
35public class BSLinkset
36{
37 private static string LogHeader = "[BULLETSIM LINKSET]";
38
39 private BSPrim m_linksetRoot;
40 public BSPrim Root { get { return m_linksetRoot; } }
41
42 private BSScene m_scene;
43
44 private List<BSPrim> m_children;
45
46 // We lock the diddling of linkset classes to prevent any badness.
47 // This locks the modification of the instances of this class. Changes
48 // to the physical representation is done via the tainting mechenism.
49 private object m_linksetActivityLock = new Object();
50
51 // We keep the prim's mass in the linkset structure since it could be dependent on other prims
52 private float m_mass;
53 public float Mass
54 {
55 get
56 {
57 m_mass = ComputeLinksetMass();
58 return m_mass;
59 }
60 }
61
62 public OMV.Vector3 CenterOfMass
63 {
64 get { return ComputeLinksetCenterOfMass(); }
65 }
66
67 public OMV.Vector3 GeometricCenter
68 {
69 get { return ComputeLinksetGeometricCenter(); }
70 }
71
72 public BSLinkset(BSScene scene, BSPrim parent)
73 {
74 // A simple linkset of one (no children)
75 m_scene = scene;
76 m_linksetRoot = parent;
77 m_children = new List<BSPrim>();
78 m_mass = parent.MassRaw;
79 }
80
81 // Link to a linkset where the child knows the parent.
82 // Parent changing should not happen so do some sanity checking.
83 // We return the parent's linkset so the child can track it's membership.
84 public BSLinkset AddMeToLinkset(BSPrim child, BSPrim parent)
85 {
86 lock (m_linksetActivityLock)
87 {
88 parent.Linkset.AddChildToLinkset(child);
89 }
90 return parent.Linkset;
91 }
92
93 public BSLinkset RemoveMeFromLinkset(BSPrim child)
94 {
95 lock (m_linksetActivityLock)
96 {
97 if (IsRoot(child))
98 {
99 // if root of linkset, take the linkset apart
100 while (m_children.Count > 0)
101 {
102 // Note that we don't do a foreach because the remove routine
103 // takes it out of the list.
104 RemoveChildFromLinkset(m_children[0]);
105 }
106 m_children.Clear(); // just to make sure
107 }
108 else
109 {
110 // Just removing a child from an existing linkset
111 RemoveChildFromLinkset(child);
112 }
113 }
114
115 // The child is down to a linkset of just itself
116 return new BSLinkset(m_scene, child);
117 }
118
119 // An existing linkset had one of its members rebuilt or something.
120 // Undo all the physical linking and rebuild the physical linkset.
121 public bool RefreshLinkset(BSPrim requestor)
122 {
123 return true;
124 }
125
126
127 // Return 'true' if the passed object is the root object of this linkset
128 public bool IsRoot(BSPrim requestor)
129 {
130 return (requestor.LocalID == m_linksetRoot.LocalID);
131 }
132
133 // Return 'true' if this linkset has any children (more than the root member)
134 public bool HasAnyChildren { get { return (m_children.Count > 0); } }
135
136 // Return 'true' if this child is in this linkset
137 public bool HasChild(BSPrim child)
138 {
139 bool ret = false;
140 foreach (BSPrim bp in m_children)
141 {
142 if (child.LocalID == bp.LocalID)
143 {
144 ret = true;
145 break;
146 }
147 }
148 return ret;
149 }
150
151 private float ComputeLinksetMass()
152 {
153 float mass = m_linksetRoot.Mass;
154 foreach (BSPrim bp in m_children)
155 {
156 mass += bp.Mass;
157 }
158 return mass;
159 }
160
161 private OMV.Vector3 ComputeLinksetCenterOfMass()
162 {
163 OMV.Vector3 com = m_linksetRoot.Position * m_linksetRoot.MassRaw;
164 float totalMass = m_linksetRoot.MassRaw;
165
166 foreach (BSPrim bp in m_children)
167 {
168 com += bp.Position * bp.MassRaw;
169 totalMass += bp.MassRaw;
170 }
171 com /= totalMass;
172
173 return com;
174 }
175
176 private OMV.Vector3 ComputeLinksetGeometricCenter()
177 {
178 OMV.Vector3 com = m_linksetRoot.Position;
179
180 foreach (BSPrim bp in m_children)
181 {
182 com += bp.Position * bp.MassRaw;
183 }
184 com /= m_children.Count + 1;
185
186 return com;
187 }
188
189 // I am the root of a linkset and a new child is being added
190 public void AddChildToLinkset(BSPrim pchild)
191 {
192 BSPrim child = pchild;
193 if (!HasChild(child))
194 {
195 m_children.Add(child);
196
197 m_scene.TaintedObject(delegate()
198 {
199 DebugLog("{0}: AddChildToLinkset: adding child {1} to {2}", LogHeader, child.LocalID, m_linksetRoot.LocalID);
200 DetailLog("{0},AddChildToLinkset,child={1}", m_linksetRoot.LocalID, pchild.LocalID);
201 PhysicallyLinkAChildToRoot(pchild); // build the physical binding between me and the child
202 });
203 }
204 return;
205 }
206
207 // I am the root of a linkset and one of my children is being removed.
208 // Safe to call even if the child is not really in my linkset.
209 public void RemoveChildFromLinkset(BSPrim pchild)
210 {
211 BSPrim child = pchild;
212
213 if (m_children.Remove(child))
214 {
215 m_scene.TaintedObject(delegate()
216 {
217 DebugLog("{0}: RemoveChildFromLinkset: Removing constraint to {1}", LogHeader, child.LocalID);
218 DetailLog("{0},RemoveChildFromLinkset,child={1}", m_linksetRoot.LocalID, pchild.LocalID);
219
220 if (m_children.Count == 0)
221 {
222 // if the linkset is empty, make sure all linkages have been removed
223 PhysicallyUnlinkAllChildrenFromRoot();
224 }
225 else
226 {
227 PhysicallyUnlinkAChildFromRoot(pchild);
228 }
229 });
230 }
231 else
232 {
233 // This will happen if we remove the root of the linkset first. Non-fatal occurance.
234 // m_scene.Logger.ErrorFormat("{0}: Asked to remove child from linkset that was not in linkset", LogHeader);
235 }
236 return;
237 }
238
239 // Create a constraint between me (root of linkset) and the passed prim (the child).
240 // Called at taint time!
241 private void PhysicallyLinkAChildToRoot(BSPrim childPrim)
242 {
243 // Zero motion for children so they don't interpolate
244 childPrim.ZeroMotion();
245
246 // relative position normalized to the root prim
247 OMV.Quaternion invThisOrientation = OMV.Quaternion.Inverse(m_linksetRoot.Orientation);
248 OMV.Vector3 childRelativePosition = (childPrim.Position - m_linksetRoot.Position) * invThisOrientation;
249
250 // relative rotation of the child to the parent
251 OMV.Quaternion childRelativeRotation = invThisOrientation * childPrim.Orientation;
252
253 // create a constraint that allows no freedom of movement between the two objects
254 // http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?t=4818
255 // DebugLog("{0}: CreateLinkset: Adding a constraint between root prim {1} and child prim {2}", LogHeader, LocalID, childPrim.LocalID);
256 DetailLog("{0},LinkAChildToMe,taint,root={1},child={2}", m_linksetRoot.LocalID, m_linksetRoot.LocalID, childPrim.LocalID);
257 BSConstraint constrain = m_scene.Constraints.CreateConstraint(
258 m_scene.World, m_linksetRoot.Body, childPrim.Body,
259 childRelativePosition,
260 childRelativeRotation,
261 OMV.Vector3.Zero,
262 OMV.Quaternion.Identity);
263 constrain.SetLinearLimits(OMV.Vector3.Zero, OMV.Vector3.Zero);
264 constrain.SetAngularLimits(OMV.Vector3.Zero, OMV.Vector3.Zero);
265
266 // tweek the constraint to increase stability
267 constrain.UseFrameOffset(m_scene.BoolNumeric(m_scene.Params.linkConstraintUseFrameOffset));
268 constrain.TranslationalLimitMotor(m_scene.BoolNumeric(m_scene.Params.linkConstraintEnableTransMotor),
269 m_scene.Params.linkConstraintTransMotorMaxVel,
270 m_scene.Params.linkConstraintTransMotorMaxForce);
271
272 }
273
274 // Remove linkage between myself and a particular child
275 // Called at taint time!
276 private void PhysicallyUnlinkAChildFromRoot(BSPrim childPrim)
277 {
278 DebugLog("{0}: PhysicallyUnlinkAChildFromRoot: RemoveConstraint between root prim {1} and child prim {2}",
279 LogHeader, m_linksetRoot.LocalID, childPrim.LocalID);
280 DetailLog("{0},PhysicallyUnlinkAChildFromRoot,taint,root={1},child={2}", m_linksetRoot.LocalID, m_linksetRoot.LocalID, childPrim.LocalID);
281 // BulletSimAPI.RemoveConstraint(_scene.WorldID, LocalID, childPrim.LocalID);
282 m_scene.Constraints.RemoveAndDestroyConstraint(m_linksetRoot.Body, childPrim.Body);
283 }
284
285 // Remove linkage between myself and any possible children I might have
286 // Called at taint time!
287 private void PhysicallyUnlinkAllChildrenFromRoot()
288 {
289 // DebugLog("{0}: PhysicallyUnlinkAllChildren:", LogHeader);
290 DetailLog("{0},PhysicallyUnlinkAllChildren,taint", m_linksetRoot.LocalID);
291 m_scene.Constraints.RemoveAndDestroyConstraint(m_linksetRoot.Body);
292 // BulletSimAPI.RemoveConstraintByID(_scene.WorldID, LocalID);
293 }
294
295 // Invoke the detailed logger and output something if it's enabled.
296 private void DebugLog(string msg, params Object[] args)
297 {
298 m_scene.Logger.DebugFormat(msg, args);
299 }
300
301 // Invoke the detailed logger and output something if it's enabled.
302 private void DetailLog(string msg, params Object[] args)
303 {
304 m_scene.PhysicsLogging.Write(msg, args);
305 }
306
307}
308}