aboutsummaryrefslogtreecommitdiffstatshomepage
path: root/OpenSim/Region/Physics/BulletSPlugin/BSLinksetConstraints.cs
blob: 87716b4ef3e69dd343bf50c82dde980e09fffcde (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
/*
 * 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.Text;

using OpenSim.Region.OptionalModules.Scripting;

using OMV = OpenMetaverse;

namespace OpenSim.Region.Physics.BulletSPlugin
{
public sealed class BSLinksetConstraints : BSLinkset
{
    // private static string LogHeader = "[BULLETSIM LINKSET CONSTRAINTS]";

    public class BSLinkInfoConstraint : BSLinkInfo
    {
        public ConstraintType constraintType;
        public BSConstraint constraint;
        public OMV.Vector3 linearLimitLow;
        public OMV.Vector3 linearLimitHigh;
        public OMV.Vector3 angularLimitLow;
        public OMV.Vector3 angularLimitHigh;
        public bool useFrameOffset;
        public bool enableTransMotor;
        public float transMotorMaxVel;
        public float transMotorMaxForce;
        public float cfm;
        public float erp;
        public float solverIterations;
        //
        public OMV.Vector3 frameInAloc;
        public OMV.Quaternion frameInArot;
        public OMV.Vector3 frameInBloc;
        public OMV.Quaternion frameInBrot;
        // Spring
        public float springDamping;
        public float springStiffness;

        public BSLinkInfoConstraint(BSPrimLinkable pMember)
            : base(pMember)
        {
            constraint = null;
            ResetLink();
        }

        // Set all the parameters for this constraint to a fixed, non-movable constraint.
        public override void ResetLink()
        {
            // constraintType = ConstraintType.D6_CONSTRAINT_TYPE;
            constraintType = ConstraintType.FIXED_CONSTRAINT_TYPE;
            linearLimitLow = OMV.Vector3.Zero;
            linearLimitHigh = OMV.Vector3.Zero;
            angularLimitLow = OMV.Vector3.Zero;
            angularLimitHigh = OMV.Vector3.Zero;
            useFrameOffset = BSParam.LinkConstraintUseFrameOffset;
            enableTransMotor = BSParam.LinkConstraintEnableTransMotor;
            transMotorMaxVel = BSParam.LinkConstraintTransMotorMaxVel;
            transMotorMaxForce = BSParam.LinkConstraintTransMotorMaxForce;
            cfm = BSParam.LinkConstraintCFM;
            erp = BSParam.LinkConstraintERP;
            solverIterations = BSParam.LinkConstraintSolverIterations;
            frameInAloc = OMV.Vector3.Zero;
            frameInArot = OMV.Quaternion.Identity;
            frameInBloc = OMV.Vector3.Zero;
            frameInBrot = OMV.Quaternion.Identity;
            springDamping = -1f;
            springStiffness = -1f;
        }

        // Given a constraint, apply the current constraint parameters to same.
        public override void SetLinkParameters(BSConstraint constrain)
        {
            switch (constraintType)
            {
                case ConstraintType.FIXED_CONSTRAINT_TYPE:
                case ConstraintType.D6_CONSTRAINT_TYPE:
                    BSConstraint6Dof constrain6dof = constrain as BSConstraint6Dof;
                    if (constrain6dof != null)
                    {
                        // NOTE: D6_SPRING_CONSTRAINT_TYPE should be updated if you change any of this code.
                        // zero linear and angular limits makes the objects unable to move in relation to each other
                        constrain6dof.SetLinearLimits(linearLimitLow, linearLimitHigh);
                        constrain6dof.SetAngularLimits(angularLimitLow, angularLimitHigh);

                        // tweek the constraint to increase stability
                        constrain6dof.UseFrameOffset(useFrameOffset);
                        constrain6dof.TranslationalLimitMotor(enableTransMotor, transMotorMaxVel, transMotorMaxForce);
                        constrain6dof.SetCFMAndERP(cfm, erp);
                        if (solverIterations != 0f)
                        {
                            constrain6dof.SetSolverIterations(solverIterations);
                        }
                    }
                    break;
                case ConstraintType.D6_SPRING_CONSTRAINT_TYPE:
                    BSConstraintSpring constrainSpring = constrain as BSConstraintSpring;
                    if (constrainSpring != null)
                    {
                        // zero linear and angular limits makes the objects unable to move in relation to each other
                        constrainSpring.SetLinearLimits(linearLimitLow, linearLimitHigh);
                        constrainSpring.SetAngularLimits(angularLimitLow, angularLimitHigh);

                        // tweek the constraint to increase stability
                        constrainSpring.UseFrameOffset(useFrameOffset);
                        constrainSpring.TranslationalLimitMotor(enableTransMotor, transMotorMaxVel, transMotorMaxForce);
                        constrainSpring.SetCFMAndERP(cfm, erp);
                        if (solverIterations != 0f)
                        {
                            constrainSpring.SetSolverIterations(solverIterations);
                        }
                        for (int ii = 0; ii < 6; ii++)
                        {
                            if (springDamping != -1)
                                constrainSpring.SetDamping(ii, springDamping);
                            if (springStiffness != -1)
                            constrainSpring.SetStiffness(ii, springStiffness);
                        }
                    }
                    break;
                default:
                    break;
            }
        }

        // Return 'true' if the property updates from the physics engine should be reported
        //    to the simulator.
        // If the constraint is fixed, we don't need to report as the simulator and viewer will
        //    report the right things.
        public override bool ShouldUpdateChildProperties()
        {
            bool ret = true;

            if (constraintType == ConstraintType.FIXED_CONSTRAINT_TYPE)
                ret = false;

            return ret;
        }
    }

    public BSLinksetConstraints(BSScene scene, BSPrimLinkable parent) : base(scene, parent)
    {
        LinksetImpl = LinksetImplementation.Constraint;
    }

    private static string LogHeader = "[BULLETSIM LINKSET CONSTRAINT]";

    // When physical properties are changed the linkset needs to recalculate
    //   its internal properties.
    // This is queued in the 'post taint' queue so the
    //   refresh will happen once after all the other taints are applied.
    public override void Refresh(BSPrimLinkable requestor)
    {
        ScheduleRebuild(requestor);
        base.Refresh(requestor);

    }

    private void ScheduleRebuild(BSPrimLinkable requestor)
    {
        DetailLog("{0},BSLinksetConstraint.ScheduleRebuild,,rebuilding={1},hasChildren={2},actuallyScheduling={3}",
                            requestor.LocalID, Rebuilding, HasAnyChildren, (!Rebuilding && HasAnyChildren));

        // When rebuilding, it is possible to set properties that would normally require a rebuild.
        //    If already rebuilding, don't request another rebuild.
        //    If a linkset with just a root prim (simple non-linked prim) don't bother rebuilding.
        if (!Rebuilding && HasAnyChildren)
        {
            // Queue to happen after all the other taint processing
            m_physicsScene.PostTaintObject("BSLinksetContraints.Refresh", requestor.LocalID, delegate()
                {
                    if (HasAnyChildren)
                        RecomputeLinksetConstraints();
                });
        }
    }

    // The object is going dynamic (physical). Do any setup necessary
    //     for a dynamic linkset.
    // Only the state of the passed object can be modified. The rest of the linkset
    //     has not yet been fully constructed.
    // Return 'true' if any properties updated on the passed object.
    // Called at taint-time!
    public override bool MakeDynamic(BSPrimLinkable child)
    {
        bool ret = false;
        DetailLog("{0},BSLinksetConstraints.MakeDynamic,call,IsRoot={1}", child.LocalID, IsRoot(child));
        if (IsRoot(child))
        {
            // The root is going dynamic. Rebuild the linkset so parts and mass get computed properly.
            Refresh(LinksetRoot);
        }
        return ret;
    }

    // The object is going static (non-physical). Do any setup necessary for a static linkset.
    // Return 'true' if any properties updated on the passed object.
    // This doesn't normally happen -- OpenSim removes the objects from the physical
    //     world if it is a static linkset.
    // Called at taint-time!
    public override bool MakeStatic(BSPrimLinkable child)
    {
        bool ret = false;

        DetailLog("{0},BSLinksetConstraint.MakeStatic,call,IsRoot={1}", child.LocalID, IsRoot(child));
        child.ClearDisplacement();
        if (IsRoot(child))
        {
            // Schedule a rebuild to verify that the root shape is set to the real shape.
            Refresh(LinksetRoot);
        }
        return ret;
    }

    // Called at taint-time!!
    public override void UpdateProperties(UpdatedProperties whichUpdated, BSPrimLinkable pObj)
    {
        // Nothing to do for constraints on property updates
    }

    // Routine called when rebuilding the body of some member of the linkset.
    // Destroy all the constraints have have been made to root and set
    //     up to rebuild the constraints before the next simulation step.
    // Returns 'true' of something was actually removed and would need restoring
    // Called at taint-time!!
    public override bool RemoveDependencies(BSPrimLinkable child)
    {
        bool ret = false;

        DetailLog("{0},BSLinksetConstraint.RemoveDependencies,removeChildrenForRoot,rID={1},rBody={2}",
                                    child.LocalID, LinksetRoot.LocalID, LinksetRoot.PhysBody.AddrString);

        lock (m_linksetActivityLock)
        {
            // Just undo all the constraints for this linkset. Rebuild at the end of the step.
            ret = PhysicallyUnlinkAllChildrenFromRoot(LinksetRoot);
            // Cause the constraints, et al to be rebuilt before the next simulation step.
            Refresh(LinksetRoot);
        }
        return ret;
    }

    // ================================================================

    // Add a new child to the linkset.
    // Called while LinkActivity is locked.
    protected override void AddChildToLinkset(BSPrimLinkable child)
    {
        if (!HasChild(child))
        {
            m_children.Add(child, new BSLinkInfoConstraint(child));

            DetailLog("{0},BSLinksetConstraints.AddChildToLinkset,call,child={1}", LinksetRoot.LocalID, child.LocalID);

            // Cause constraints and assorted properties to be recomputed before the next simulation step.
            Refresh(LinksetRoot);
        }
        return;
    }

    // Remove the specified child from the linkset.
    // Safe to call even if the child is not really in my linkset.
    protected override void RemoveChildFromLinkset(BSPrimLinkable child, bool inTaintTime)
    {
        if (m_children.Remove(child))
        {
            BSPrimLinkable rootx = LinksetRoot; // capture the root and body as of now
            BSPrimLinkable childx = child;

            DetailLog("{0},BSLinksetConstraints.RemoveChildFromLinkset,call,rID={1},rBody={2},cID={3},cBody={4}",
                            childx.LocalID,
                            rootx.LocalID, rootx.PhysBody.AddrString,
                            childx.LocalID, childx.PhysBody.AddrString);

            m_physicsScene.TaintedObject(inTaintTime, "BSLinksetConstraints.RemoveChildFromLinkset", delegate()
            {
                PhysicallyUnlinkAChildFromRoot(rootx, childx);
            });
            // See that the linkset parameters are recomputed at the end of the taint time.
            Refresh(LinksetRoot);
        }
        else
        {
            // Non-fatal occurance.
            // PhysicsScene.Logger.ErrorFormat("{0}: Asked to remove child from linkset that was not in linkset", LogHeader);
        }
        return;
    }

    // Create a constraint between me (root of linkset) and the passed prim (the child).
    // Called at taint time!
    private void PhysicallyLinkAChildToRoot(BSPrimLinkable rootPrim, BSPrimLinkable childPrim)
    {
        // Don't build the constraint when asked. Put it off until just before the simulation step.
        Refresh(rootPrim);
    }

    // Create a static constraint between the two passed objects
    private BSConstraint BuildConstraint(BSPrimLinkable rootPrim, BSLinkInfo li)
    {
        BSLinkInfoConstraint linkInfo = li as BSLinkInfoConstraint;
        if (linkInfo == null)
            return null;

        // Zero motion for children so they don't interpolate
        li.member.ZeroMotion(true);

        BSConstraint constrain = null;

        switch (linkInfo.constraintType)
        {
            case ConstraintType.FIXED_CONSTRAINT_TYPE:
            case ConstraintType.D6_CONSTRAINT_TYPE:
                // Relative position normalized to the root prim
                // Essentually a vector pointing from center of rootPrim to center of li.member
                OMV.Vector3 childRelativePosition = linkInfo.member.Position - rootPrim.Position;

                // real world coordinate of midpoint between the two objects
                OMV.Vector3 midPoint = rootPrim.Position + (childRelativePosition / 2);

                DetailLog("{0},BSLinksetConstraint.BuildConstraint,6Dof,rBody={1},cBody={2},rLoc={3},cLoc={4},midLoc={5}",
                                                rootPrim.LocalID, rootPrim.PhysBody, linkInfo.member.PhysBody,
                                                rootPrim.Position, linkInfo.member.Position, midPoint);

                // create a constraint that allows no freedom of movement between the two objects
                // http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?t=4818

                constrain = new BSConstraint6Dof(
                                    m_physicsScene.World, rootPrim.PhysBody, linkInfo.member.PhysBody, midPoint, true, true );

                /* NOTE: below is an attempt to build constraint with full frame computation, etc.
                 *     Using the midpoint is easier since it lets the Bullet code manipulate the transforms
                 *     of the objects.
                 * Code left for future programmers.
                // ==================================================================================
                // relative position normalized to the root prim
                OMV.Quaternion invThisOrientation = OMV.Quaternion.Inverse(rootPrim.Orientation);
                OMV.Vector3 childRelativePosition = (liConstraint.member.Position - rootPrim.Position) * invThisOrientation;

                // relative rotation of the child to the parent
                OMV.Quaternion childRelativeRotation = invThisOrientation * liConstraint.member.Orientation;
                OMV.Quaternion inverseChildRelativeRotation = OMV.Quaternion.Inverse(childRelativeRotation);

                DetailLog("{0},BSLinksetConstraint.PhysicallyLinkAChildToRoot,taint,root={1},child={2}", rootPrim.LocalID, rootPrim.LocalID, liConstraint.member.LocalID);
                constrain = new BS6DofConstraint(
                                PhysicsScene.World, rootPrim.Body, liConstraint.member.Body,
                                OMV.Vector3.Zero,
                                OMV.Quaternion.Inverse(rootPrim.Orientation),
                                OMV.Vector3.Zero,
                                OMV.Quaternion.Inverse(liConstraint.member.Orientation),
                                true,
                                true
                                );
                // ==================================================================================
                */

                break;
            case ConstraintType.D6_SPRING_CONSTRAINT_TYPE:
                constrain = new BSConstraintSpring(m_physicsScene.World, rootPrim.PhysBody, linkInfo.member.PhysBody,
                                linkInfo.frameInAloc, linkInfo.frameInArot, linkInfo.frameInBloc, linkInfo.frameInBrot,
                                true /*useLinearReferenceFrameA*/,
                                true /*disableCollisionsBetweenLinkedBodies*/);
                DetailLog("{0},BSLinksetConstraint.BuildConstraint,spring,root={1},rBody={2},child={3},cBody={4},rLoc={5},cLoc={6},midLoc={7}",
                                                rootPrim.LocalID,
                                                rootPrim.LocalID, rootPrim.PhysBody.AddrString,
                                                linkInfo.member.LocalID, linkInfo.member.PhysBody.AddrString,
                                                rootPrim.Position, linkInfo.member.Position);

                break;
            default:
                break;
        }

        linkInfo.SetLinkParameters(constrain);

        m_physicsScene.Constraints.AddConstraint(constrain);

        return constrain;
    }

    // Remove linkage between the linkset root and a particular child
    // The root and child bodies are passed in because we need to remove the constraint between
    //      the bodies that were present at unlink time.
    // Called at taint time!
    private bool PhysicallyUnlinkAChildFromRoot(BSPrimLinkable rootPrim, BSPrimLinkable childPrim)
    {
        bool ret = false;
        DetailLog("{0},BSLinksetConstraint.PhysicallyUnlinkAChildFromRoot,taint,root={1},rBody={2},child={3},cBody={4}",
                            rootPrim.LocalID,
                            rootPrim.LocalID, rootPrim.PhysBody.AddrString,
                            childPrim.LocalID, childPrim.PhysBody.AddrString);

        // Find the constraint for this link and get rid of it from the overall collection and from my list
        if (m_physicsScene.Constraints.RemoveAndDestroyConstraint(rootPrim.PhysBody, childPrim.PhysBody))
        {
            // Make the child refresh its location
            m_physicsScene.PE.PushUpdate(childPrim.PhysBody);
            ret = true;
        }

        return ret;
    }

    // Remove linkage between myself and any possible children I might have.
    // Returns 'true' of any constraints were destroyed.
    // Called at taint time!
    private bool PhysicallyUnlinkAllChildrenFromRoot(BSPrimLinkable rootPrim)
    {
        DetailLog("{0},BSLinksetConstraint.PhysicallyUnlinkAllChildren,taint", rootPrim.LocalID);

        return m_physicsScene.Constraints.RemoveAndDestroyConstraint(rootPrim.PhysBody);
    }

    // Call each of the constraints that make up this linkset and recompute the
    //    various transforms and variables. Create constraints of not created yet.
    // Called before the simulation step to make sure the constraint based linkset
    //    is all initialized.
    // Called at taint time!!
    private void RecomputeLinksetConstraints()
    {
        float linksetMass = LinksetMass;
        LinksetRoot.UpdatePhysicalMassProperties(linksetMass, true);

        DetailLog("{0},BSLinksetConstraint.RecomputeLinksetConstraints,set,rBody={1},linksetMass={2}",
                            LinksetRoot.LocalID, LinksetRoot.PhysBody.AddrString, linksetMass);

        try
        {
            Rebuilding = true;

            // There is no reason to build all this physical stuff for a non-physical linkset.
            if (!LinksetRoot.IsPhysicallyActive || !HasAnyChildren)
            {
                DetailLog("{0},BSLinksetConstraint.RecomputeLinksetCompound,notPhysicalOrNoChildren", LinksetRoot.LocalID);
                return; // Note the 'finally' clause at the botton which will get executed.
            }

            ForEachLinkInfo((li) =>
            {
                // A child in the linkset physically shows the mass of the whole linkset.
                // This allows Bullet to apply enough force on the child to move the whole linkset.
                // (Also do the mass stuff before recomputing the constraint so mass is not zero.)
                li.member.UpdatePhysicalMassProperties(linksetMass, true);

                BSConstraint constrain;
                if (!m_physicsScene.Constraints.TryGetConstraint(LinksetRoot.PhysBody, li.member.PhysBody, out constrain))
                {
                    // If constraint doesn't exist yet, create it.
                    constrain = BuildConstraint(LinksetRoot, li);
                }
                li.SetLinkParameters(constrain);
                constrain.RecomputeConstraintVariables(linksetMass);

                // PhysicsScene.PE.DumpConstraint(PhysicsScene.World, constrain.Constraint);    // DEBUG DEBUG
                return false;   // 'false' says to keep processing other members
            });
        }
        finally
        {
            Rebuilding = false;
        }
    }

    #region Extension
    public override object Extension(string pFunct, params object[] pParams)
    {
        object ret = null;
        switch (pFunct)
        {
            // pParams = [ BSPhysObject child, integer linkType ]
            case ExtendedPhysics.PhysFunctChangeLinkType:
                if (pParams.Length > 1)
                {
                    int requestedType = (int)pParams[1];
                    DetailLog("{0},BSLinksetConstraint.SetLinkType,requestedType={1}", LinksetRoot.LocalID, requestedType);
                    if (requestedType == (int)ConstraintType.FIXED_CONSTRAINT_TYPE
                        || requestedType == (int)ConstraintType.D6_CONSTRAINT_TYPE
                        || requestedType == (int)ConstraintType.D6_SPRING_CONSTRAINT_TYPE
                        || requestedType == (int)ConstraintType.HINGE_CONSTRAINT_TYPE
                        || requestedType == (int)ConstraintType.CONETWIST_CONSTRAINT_TYPE
                        || requestedType == (int)ConstraintType.SLIDER_CONSTRAINT_TYPE)
                    {
                        BSPrimLinkable child = pParams[0] as BSPrimLinkable;
                        if (child != null)
                        {
                            m_physicsScene.TaintedObject("BSLinksetConstraint.PhysFunctChangeLinkType", delegate()
                            {
                                // Pick up all the constraints currently created.
                                RemoveDependencies(child);

                                BSLinkInfo linkInfo = null;
                                if (TryGetLinkInfo(child, out linkInfo))
                                {
                                    BSLinkInfoConstraint linkInfoC = linkInfo as BSLinkInfoConstraint;
                                    if (linkInfoC != null)
                                    {
                                        // Setting to fixed is easy. The reset state is the fixed link configuration.
                                        linkInfoC.ResetLink();
                                        linkInfoC.constraintType = (ConstraintType)requestedType;
                                        ret = (object)true;
                                        DetailLog("{0},BSLinksetConstraint.SetLinkType,link={1},type={2}",
                                                    linkInfo.member.LocalID, linkInfo.member.LocalID, linkInfoC.constraintType);
                                    }
                                    else
                                    {
                                        DetailLog("{0},BSLinksetConstraint.SetLinkType,linkInfoNotConstraint,childID={1}", LinksetRoot.LocalID, child.LocalID);
                                    }
                                }
                                else
                                {
                                    DetailLog("{0},BSLinksetConstraint.SetLinkType,noLinkInfoForChild,childID={1}", LinksetRoot.LocalID, child.LocalID);
                                }
                                // Cause the whole linkset to be rebuilt in post-taint time.
                                Refresh(child);
                            });
                        }
                        else
                        {
                            DetailLog("{0},BSLinksetConstraint.SetLinkType,childNotBSPrimLinkable", LinksetRoot.LocalID);
                        }
                    }
                    else
                    {
                        DetailLog("{0},BSLinksetConstraint.SetLinkType,illegalRequestedType,reqested={1},spring={2}",
                                        LinksetRoot.LocalID, requestedType, ((int)ConstraintType.D6_SPRING_CONSTRAINT_TYPE));
                    }
                }
                break;
            // pParams = []
            case ExtendedPhysics.PhysFunctGetLinkType:
                if (pParams.Length > 0)
                {
                    BSPrimLinkable child = pParams[0] as BSPrimLinkable;
                    if (child != null)
                    {
                        BSLinkInfo linkInfo = null;
                        if (TryGetLinkInfo(child, out linkInfo))
                        {
                            BSLinkInfoConstraint linkInfoC = linkInfo as BSLinkInfoConstraint;
                            if (linkInfoC != null)
                            {
                                ret = (object)(int)linkInfoC.constraintType;
                                DetailLog("{0},BSLinksetConstraint.GetLinkType,link={1},type={2}",
                                            linkInfo.member.LocalID, linkInfo.member.LocalID, linkInfoC.constraintType);

                            }
                        }
                    }
                }
                break;
            // pParams = [ BSPhysObject child, int op, object opParams, int op, object opParams, ... ]
            case ExtendedPhysics.PhysFunctChangeLinkParams:
                // There should be two parameters: the childActor and a list of parameters to set
                try
                {
                    if (pParams.Length > 1)
                    {
                        BSPrimLinkable child = pParams[0] as BSPrimLinkable;
                        BSLinkInfo baseLinkInfo = null;
                        if (TryGetLinkInfo(child, out baseLinkInfo))
                        {
                            BSLinkInfoConstraint linkInfo = baseLinkInfo as BSLinkInfoConstraint;
                            if (linkInfo != null)
                            {
                                float valueFloat;
                                bool valueBool;
                                OMV.Vector3 valueVector;
                                OMV.Quaternion valueQuaternion;

                                int opIndex = 1;
                                while (opIndex < pParams.Length)
                                {
                                    int thisOp = (int)pParams[opIndex];
                                    DetailLog("{0},BSLinksetConstraint.ChangeLinkParams2,op={1},val={2}",
                                                        linkInfo.member.LocalID, thisOp, pParams[opIndex+1]);
                                    switch (thisOp)
                                    {
                                        case ExtendedPhysics.PHYS_PARAM_FRAMEINA_LOC:
                                            valueVector = (OMV.Vector3)pParams[opIndex + 1];
                                            linkInfo.frameInAloc = valueVector;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_FRAMEINA_ROT:
                                            valueQuaternion = (OMV.Quaternion)pParams[opIndex + 1];
                                            linkInfo.frameInArot = valueQuaternion;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_FRAMEINB_LOC:
                                            valueVector = (OMV.Vector3)pParams[opIndex + 1];
                                            linkInfo.frameInBloc = valueVector;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_FRAMEINB_ROT:
                                            valueQuaternion = (OMV.Quaternion)pParams[opIndex + 1];
                                            linkInfo.frameInBrot = valueQuaternion;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_LINEAR_LIMIT_LOW:
                                            valueVector = (OMV.Vector3)pParams[opIndex + 1];
                                            linkInfo.linearLimitLow = valueVector;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_LINEAR_LIMIT_HIGH:
                                            valueVector = (OMV.Vector3)pParams[opIndex + 1];
                                            linkInfo.linearLimitHigh = valueVector;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_ANGULAR_LIMIT_LOW:
                                            valueVector = (OMV.Vector3)pParams[opIndex + 1];
                                            linkInfo.angularLimitLow = valueVector;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_ANGULAR_LIMIT_HIGH:
                                            valueVector = (OMV.Vector3)pParams[opIndex + 1];
                                            linkInfo.angularLimitHigh = valueVector;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_USE_FRAME_OFFSET:
                                            valueBool = (bool)pParams[opIndex + 1];
                                            linkInfo.useFrameOffset = valueBool;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_ENABLE_TRANSMOTOR:
                                            valueBool = (bool)pParams[opIndex + 1];
                                            linkInfo.enableTransMotor = valueBool;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_TRANSMOTOR_MAXVEL:
                                            valueFloat = (float)pParams[opIndex + 1];
                                            linkInfo.transMotorMaxVel = valueFloat;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_TRANSMOTOR_MAXFORCE:
                                            valueFloat = (float)pParams[opIndex + 1];
                                            linkInfo.transMotorMaxForce = valueFloat;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_CFM:
                                            valueFloat = (float)pParams[opIndex + 1];
                                            linkInfo.cfm = valueFloat;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_ERP:
                                            valueFloat = (float)pParams[opIndex + 1];
                                            linkInfo.erp = valueFloat;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_SOLVER_ITERATIONS:
                                            valueFloat = (float)pParams[opIndex + 1];
                                            linkInfo.solverIterations = valueFloat;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_SPRING_DAMPING:
                                            valueFloat = (float)pParams[opIndex + 1];
                                            linkInfo.springDamping = valueFloat;
                                            opIndex += 2;
                                            break;
                                        case ExtendedPhysics.PHYS_PARAM_SPRING_STIFFNESS:
                                            valueFloat = (float)pParams[opIndex + 1];
                                            linkInfo.springStiffness = valueFloat;
                                            opIndex += 2;
                                            break;
                                        default:
                                            break;
                                    }
                                }
                            }
                            // Something changed so a rebuild is in order
                            Refresh(child);
                        }
                    }
                }
                catch (Exception e)
                {
                    // There are many ways to mess up the parameters. If not just right don't fail without some error.
                    m_physicsScene.Logger.WarnFormat("{0} bad parameters in physSetLinksetParams: {1}", LogHeader, e);
                }
                break;
            default:
                ret = base.Extension(pFunct, pParams);
                break;
        }
        return ret;
    }
    #endregion // Extension

}
}