/// <summary>
        /// Creates a <see cref="Ragdoll"/> for an Xbox LIVE Avatar. (Only available on Xbox 360.)
        /// </summary>
        /// <param name="skeleton">The skeleton of the Xbox LIVE Avatar.</param>
        /// <param name="simulation">The simulation.</param>
        /// <returns>The avatar ragdoll.</returns>
        /// <exception cref="ArgumentNullException">
        /// <paramref name="skeleton"/> or <paramref name="simulation"/> is 
        /// <see langword="null"/>.
        /// </exception>
        /// <remarks>
        /// This method is available only in the Xbox 360 build of the 
        /// DigitalRune.Physics.Specialized.dll.
        /// </remarks>
        public static Ragdoll CreateAvatarRagdoll(Skeleton skeleton, Simulation simulation)
        {
            if (skeleton == null)
            throw new ArgumentNullException("skeleton");
              if (simulation == null)
            throw new ArgumentNullException("simulation");

              var ragdoll = new Ragdoll();

              // The lists ragdoll.Bodies, ragdoll.BodyOffsets and _motors contain one entry per bone - even if there
              // is no RigidBody for this bone. - This wastes memory but simplifies the code.
              for (int i = 0; i < AvatarRenderer.BoneCount; i++)
              {
            ragdoll.Bodies.Add(null);
            ragdoll.BodyOffsets.Add(Pose.Identity);
            ragdoll.Joints.Add(null);
            ragdoll.Limits.Add(null);
            ragdoll.Motors.Add(null);
              }

              // ----- Create bodies.
              // We use the same mass for all bodies. This is not physically correct but it makes the
              // simulation more stable, for several reasons:
              // - It is better to avoid large mass differences. Therefore, all limbs have the same mass.
              // - Capsule shapes have a low inertia value about their height axis. This causes instability
              //   and it is better to use larger inertia values.
              var massFrame = MassFrame.FromShapeAndMass(new SphereShape(0.2f), Vector3F.One, 4, 0.1f, 1);

              // Use standard material.
              var material = new UniformMaterial();

              // Create rigid bodies for the important bones. The shapes have been manually adapted to
              // produce useful results for thin and overweight avatars.
              // Without offset, the bodies are centered at the joint. ragdoll.BodyOffsets stores an offset pose
              // for each body. Instead, we could use TransformedShape but we can easily handle that
              // ourselves.
              // The collar bones are special, they use dummy shapes and are only used to connect the
              // shoulder bones.
              ragdoll.Bodies[(int)AvatarBone.Root] = new RigidBody(new BoxShape(0.22f, 0.16f, 0.16f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.Root] = new Pose(new Vector3F(0, -0.08f, -0.01f), QuaternionF.CreateRotationX(-0.0f));
              ragdoll.Bodies[(int)AvatarBone.BackLower] = new RigidBody(new BoxShape(0.22f, 0.16f, 0.16f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.BackLower] = new Pose(new Vector3F(0, 0.08f, -0.01f), QuaternionF.CreateRotationX(-0.0f));
              ragdoll.Bodies[(int)AvatarBone.BackUpper] = new RigidBody(new BoxShape(0.22f, 0.16f, 0.16f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.BackUpper] = new Pose(new Vector3F(0, 0.08f, -0.01f), QuaternionF.CreateRotationX(-0.1f));
              ragdoll.Bodies[(int)AvatarBone.Neck] = new RigidBody(new CapsuleShape(0.04f, 0.09f), massFrame, material);
              ragdoll.Bodies[(int)AvatarBone.Head] = new RigidBody(new SphereShape(0.15f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.Head] = new Pose(new Vector3F(0, 0.1f, 0));
              ragdoll.Bodies[(int)AvatarBone.CollarLeft] = new RigidBody(Shape.Empty, massFrame, material);
              ragdoll.Bodies[(int)AvatarBone.CollarRight] = new RigidBody(Shape.Empty, massFrame, material);
              ragdoll.Bodies[(int)AvatarBone.ShoulderLeft] = new RigidBody(new CapsuleShape(0.04f, 0.25f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.ShoulderLeft] = new Pose(new Vector3F(0.08f, 0, -0.02f), QuaternionF.CreateRotationZ(ConstantsF.PiOver2));
              ragdoll.Bodies[(int)AvatarBone.ShoulderRight] = new RigidBody(new CapsuleShape(0.04f, 0.25f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.ShoulderRight] = new Pose(new Vector3F(-0.08f, 0, -0.02f), QuaternionF.CreateRotationZ(ConstantsF.PiOver2));
              ragdoll.Bodies[(int)AvatarBone.ElbowLeft] = new RigidBody(new CapsuleShape(0.04f, 0.21f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.ElbowLeft] = new Pose(new Vector3F(0.06f, 0, -0.02f), QuaternionF.CreateRotationZ(ConstantsF.PiOver2));
              ragdoll.Bodies[(int)AvatarBone.ElbowRight] = new RigidBody(new CapsuleShape(0.04f , 0.21f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.ElbowRight] = new Pose(new Vector3F(-0.06f, 0, -0.02f), QuaternionF.CreateRotationZ(ConstantsF.PiOver2));
              ragdoll.Bodies[(int)AvatarBone.WristLeft] = new RigidBody(new BoxShape(0.1f, 0.04f, 0.1f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.WristLeft] = new Pose(new Vector3F(0.06f, -0.02f, -0.01f), QuaternionF.CreateRotationZ(0.0f));
              ragdoll.Bodies[(int)AvatarBone.WristRight] = new RigidBody(new BoxShape(0.1f, 0.04f, 0.1f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.WristRight] = new Pose(new Vector3F(-0.06f, -0.02f, -0.01f), QuaternionF.CreateRotationZ(0.0f));
              ragdoll.Bodies[(int)AvatarBone.HipLeft] = new RigidBody(new CapsuleShape(0.06f, 0.34f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.HipLeft] = new Pose(new Vector3F(0, -0.14f, -0.02f), QuaternionF.CreateRotationX(0.1f));
              ragdoll.Bodies[(int)AvatarBone.HipRight] = new RigidBody(new CapsuleShape(0.06f, 0.34f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.HipRight] = new Pose(new Vector3F(0, -0.14f, -0.02f), QuaternionF.CreateRotationX(0.1f));
              ragdoll.Bodies[(int)AvatarBone.KneeLeft] = new RigidBody(new CapsuleShape(0.06f, 0.36f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.KneeLeft] = new Pose(new Vector3F(0, -0.18f, -0.04f), QuaternionF.CreateRotationX(0.1f));
              ragdoll.Bodies[(int)AvatarBone.KneeRight] = new RigidBody(new CapsuleShape(0.06f, 0.36f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.KneeRight] = new Pose(new Vector3F(0, -0.18f, -0.04f), QuaternionF.CreateRotationX(0.1f));
              ragdoll.Bodies[(int)AvatarBone.AnkleLeft] = new RigidBody(new BoxShape(0.1f, 0.06f, 0.22f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.AnkleLeft] = new Pose(new Vector3F(0, -0.07f, 0.05f), QuaternionF.CreateRotationZ(0));
              ragdoll.Bodies[(int)AvatarBone.AnkleRight] = new RigidBody(new BoxShape(0.1f, 0.06f, 0.22f), massFrame, material);
              ragdoll.BodyOffsets[(int)AvatarBone.AnkleRight] = new Pose(new Vector3F(0, -0.07f, 0.05f), QuaternionF.CreateRotationZ(0));

              // ----- Add joint constraints.
              const float jointErrorReduction = 0.2f;
              const float jointSoftness = 0.0001f;
              AddJoint(ragdoll, skeleton, AvatarBone.Root, AvatarBone.BackLower, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.BackLower, AvatarBone.BackUpper, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.BackUpper, AvatarBone.Neck, 0.6f, 0.000001f);
              AddJoint(ragdoll, skeleton, AvatarBone.Neck, AvatarBone.Head, 0.6f, 0.000001f);
              AddJoint(ragdoll, skeleton, AvatarBone.BackUpper, AvatarBone.CollarLeft, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.BackUpper, AvatarBone.CollarRight, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.CollarLeft, AvatarBone.ShoulderLeft, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.CollarRight, AvatarBone.ShoulderRight, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.ShoulderLeft, AvatarBone.ElbowLeft, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.ShoulderRight, AvatarBone.ElbowRight, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.ElbowLeft, AvatarBone.WristLeft, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.ElbowRight, AvatarBone.WristRight, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.Root, AvatarBone.HipLeft, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.Root, AvatarBone.HipRight, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.HipLeft, AvatarBone.KneeLeft, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.HipRight, AvatarBone.KneeRight, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.KneeLeft, AvatarBone.AnkleLeft, jointErrorReduction, jointSoftness);
              AddJoint(ragdoll, skeleton, AvatarBone.KneeRight, AvatarBone.AnkleRight, jointErrorReduction, jointSoftness);

              // ----- Add constraint limits.
              // We use TwistSwingLimits to define an allowed twist and swing cone for the joints.
              // Exceptions are the back and knees, where we use AngularLimits to create hinges.
              // (We could also create a hinge with a TwistSwingLimit where the twist axis is the hinge
              // axis and no swing is allowed - but AngularLimits create more stable hinges.)
              // Another exception are the collar bones joint. We use AngularLimits to disallow any
              // rotations.
              AddAngularLimit(ragdoll, skeleton, AvatarBone.Root, AvatarBone.BackLower,
            skeleton.GetBindPoseAbsoluteInverse((int)AvatarBone.BackLower).Rotation.Conjugated.ToRotationMatrix33(),
            skeleton.GetBindPoseAbsoluteInverse((int)AvatarBone.BackLower).Rotation.Conjugated.ToRotationMatrix33(),
            new Vector3F(-0.3f, 0, 0), new Vector3F(0.3f, 0, 0));

              AddAngularLimit(ragdoll, skeleton, AvatarBone.BackLower, AvatarBone.BackUpper,
            skeleton.GetBindPoseAbsoluteInverse((int)AvatarBone.BackUpper).Rotation.Conjugated.ToRotationMatrix33(),
            skeleton.GetBindPoseAbsoluteInverse((int)AvatarBone.BackUpper).Rotation.Conjugated.ToRotationMatrix33(),
            new Vector3F(-0.3f, 0, 0), new Vector3F(0.4f, 0, 0));

              var rotationZ90Degrees = Matrix33F.CreateRotationZ(ConstantsF.PiOver2);
              AddTwistSwingLimit(ragdoll, skeleton, AvatarBone.BackUpper, AvatarBone.Neck, rotationZ90Degrees, rotationZ90Degrees, new Vector3F(-0.1f, -0.3f, -0.3f), new Vector3F(+0.1f, +0.3f, +0.3f));

              AddTwistSwingLimit(ragdoll, skeleton, AvatarBone.Neck, AvatarBone.Head, rotationZ90Degrees, rotationZ90Degrees, new Vector3F(-0.1f, -0.6f, -0.6f), new Vector3F(+0.1f, +0.6f, +0.6f));

              AddTwistSwingLimit(ragdoll, skeleton, AvatarBone.BackUpper, AvatarBone.CollarLeft,
            skeleton.GetBindPoseAbsoluteInverse((int)AvatarBone.CollarLeft).Rotation.Conjugated.ToRotationMatrix33(),
            skeleton.GetBindPoseAbsoluteInverse((int)AvatarBone.CollarLeft).Rotation.Conjugated.ToRotationMatrix33(),
            new Vector3F(0), new Vector3F(0));

              AddTwistSwingLimit(ragdoll, skeleton, AvatarBone.BackUpper, AvatarBone.CollarRight,
            skeleton.GetBindPoseAbsoluteInverse((int)AvatarBone.CollarRight).Rotation.Conjugated.ToRotationMatrix33(),
            skeleton.GetBindPoseAbsoluteInverse((int)AvatarBone.CollarRight).Rotation.Conjugated.ToRotationMatrix33(),
            new Vector3F(0), new Vector3F(0));

              AddTwistSwingLimit(ragdoll, skeleton, AvatarBone.CollarLeft, AvatarBone.ShoulderLeft, Matrix33F.Identity, Matrix33F.CreateRotationY(0.7f), new Vector3F(-0.7f, -1.2f, -1.2f), new Vector3F(+0.7f, +1.2f, +1.2f));
              AddTwistSwingLimit(ragdoll, skeleton, AvatarBone.CollarRight, AvatarBone.ShoulderRight, Matrix33F.Identity, Matrix33F.CreateRotationY(-0.7f), new Vector3F(-0.7f, -1.2f, -1.2f), new Vector3F(+0.7f, +1.2f, +1.2f));
              AddTwistSwingLimit(ragdoll, skeleton, AvatarBone.ShoulderLeft, AvatarBone.ElbowLeft, Matrix33F.Identity, Matrix33F.CreateRotationY(1.2f), new Vector3F(-0.7f, -1.2f, -1.2f), new Vector3F(+0.7f, +1.2f, +1.2f));
              AddTwistSwingLimit(ragdoll, skeleton, AvatarBone.ShoulderRight, AvatarBone.ElbowRight, Matrix33F.Identity, Matrix33F.CreateRotationY(-1.2f), new Vector3F(-0.7f, -1.2f, -1.2f), new Vector3F(+0.7f, +1.2f, +1.2f));
              AddTwistSwingLimit(ragdoll, skeleton, AvatarBone.ElbowLeft, AvatarBone.WristLeft, Matrix33F.Identity, Matrix33F.Identity, new Vector3F(-0.7f, -0.7f, -0.7f), new Vector3F(+0.7f, +0.7f, +0.7f));
              AddTwistSwingLimit(ragdoll, skeleton, AvatarBone.ElbowRight, AvatarBone.WristRight, Matrix33F.Identity, Matrix33F.Identity, new Vector3F(-0.7f, -0.7f, -0.7f), new Vector3F(+0.7f, +0.7f, +0.7f));
              AddTwistSwingLimit(ragdoll, skeleton, AvatarBone.Root, AvatarBone.HipLeft, rotationZ90Degrees, Matrix33F.CreateRotationX(-1.2f) * Matrix33F.CreateRotationZ(ConstantsF.PiOver2 + 0.2f), new Vector3F(-0.1f, -1.5f, -0.7f), new Vector3F(+0.1f, +1.5f, +0.7f));
              AddTwistSwingLimit(ragdoll, skeleton, AvatarBone.Root, AvatarBone.HipRight, rotationZ90Degrees, Matrix33F.CreateRotationX(-1.2f) * Matrix33F.CreateRotationZ(ConstantsF.PiOver2 - 0.2f), new Vector3F(-0.1f, -1.5f, -0.7f), new Vector3F(+0.1f, +1.5f, +0.7f));

              AddAngularLimit(ragdoll, skeleton, AvatarBone.HipLeft, AvatarBone.KneeLeft,
            skeleton.GetBindPoseAbsoluteInverse((int)AvatarBone.KneeLeft).Rotation.Conjugated.ToRotationMatrix33(),
            skeleton.GetBindPoseAbsoluteInverse((int)AvatarBone.KneeLeft).Rotation.Conjugated.ToRotationMatrix33(),
            new Vector3F(0, 0, 0), new Vector3F(2.2f, 0, 0));

              AddAngularLimit(ragdoll, skeleton, AvatarBone.HipRight, AvatarBone.KneeRight,
            skeleton.GetBindPoseAbsoluteInverse((int)AvatarBone.KneeRight).Rotation.Conjugated.ToRotationMatrix33(),
            skeleton.GetBindPoseAbsoluteInverse((int)AvatarBone.KneeRight).Rotation.Conjugated.ToRotationMatrix33(),
            new Vector3F(0, 0, 0), new Vector3F(2.2f, 0, 0));

              AddTwistSwingLimit(ragdoll, skeleton, AvatarBone.KneeLeft, AvatarBone.AnkleLeft, rotationZ90Degrees, rotationZ90Degrees, new Vector3F(-0.1f, -0.7f, -0.3f), new Vector3F(+0.1f, +0.7f, +0.3f));
              AddTwistSwingLimit(ragdoll, skeleton, AvatarBone.KneeRight, AvatarBone.AnkleRight, rotationZ90Degrees, rotationZ90Degrees, new Vector3F(-0.1f, -0.7f, -0.3f), new Vector3F(+0.1f, +0.7f, +0.3f));

              // ----- Add motors
              // We use QuaternionMotors to create forces that rotate the bones into desired poses.
              // This can be used for damping, spring or animating the ragdoll.
              AddMotor(ragdoll, (AvatarBone)(-1), AvatarBone.Root);
              AddMotor(ragdoll, AvatarBone.Root, AvatarBone.BackLower);
              AddMotor(ragdoll, AvatarBone.BackLower, AvatarBone.BackUpper);
              AddMotor(ragdoll, AvatarBone.BackUpper, AvatarBone.Neck);
              AddMotor(ragdoll, AvatarBone.Neck, AvatarBone.Head);
              AddMotor(ragdoll, AvatarBone.BackUpper, AvatarBone.CollarLeft);
              AddMotor(ragdoll, AvatarBone.BackUpper, AvatarBone.CollarRight);
              AddMotor(ragdoll, AvatarBone.CollarLeft, AvatarBone.ShoulderLeft);
              AddMotor(ragdoll, AvatarBone.CollarRight, AvatarBone.ShoulderRight);
              AddMotor(ragdoll, AvatarBone.ShoulderLeft, AvatarBone.ElbowLeft);
              AddMotor(ragdoll, AvatarBone.ShoulderRight, AvatarBone.ElbowRight);
              AddMotor(ragdoll, AvatarBone.ElbowLeft, AvatarBone.WristLeft);
              AddMotor(ragdoll, AvatarBone.ElbowRight, AvatarBone.WristRight);
              AddMotor(ragdoll, AvatarBone.Root, AvatarBone.HipLeft);
              AddMotor(ragdoll, AvatarBone.Root, AvatarBone.HipRight);
              AddMotor(ragdoll, AvatarBone.HipLeft, AvatarBone.KneeLeft);
              AddMotor(ragdoll, AvatarBone.HipRight, AvatarBone.KneeRight);
              AddMotor(ragdoll, AvatarBone.KneeLeft, AvatarBone.AnkleLeft);
              AddMotor(ragdoll, AvatarBone.KneeRight, AvatarBone.AnkleRight);

              // ----- Set collision filters.
              // Collisions between connected bones have been disabled with Constraint.CollisionEnabled
              // = false in the joints. We need to disable a few other collisions.
              // Following bodies do not collide with anything. They are only used to connect other
              // bones.
              ragdoll.Bodies[(int)AvatarBone.Neck].CollisionObject.Enabled = false;
              ragdoll.Bodies[(int)AvatarBone.CollarLeft].CollisionObject.Enabled = false;
              ragdoll.Bodies[(int)AvatarBone.CollarRight].CollisionObject.Enabled = false;

              // We disable filters for following body pairs because they are usually penetrating each
              // other, which needs to be ignored.
              var filter = simulation.CollisionDomain.CollisionDetection.CollisionFilter as CollisionFilter;
              if (filter != null)
              {
            filter.Set(ragdoll.Bodies[(int)AvatarBone.BackUpper].CollisionObject, ragdoll.Bodies[(int)AvatarBone.ShoulderLeft].CollisionObject, false);
            filter.Set(ragdoll.Bodies[(int)AvatarBone.BackUpper].CollisionObject, ragdoll.Bodies[(int)AvatarBone.ShoulderRight].CollisionObject, false);
              }

              return ragdoll;
        }
        private static void AddJoint(Ragdoll ragdoll, Skeleton skeleton, AvatarBone parentBone, AvatarBone childBone, float errorReduction, float softness)
        {
            int parentIndex = (int)parentBone;
              int childIndex = (int)childBone;

              // To define AnchorPositionALocal/AnchorPositionBLocal:
              // To get the AnchorPositionALocal we apply jointPosesAbsolute[indexA].Inverse to
              // convert the joint pose from model space into the joints space of parentBone. Then we apply
              // ragdoll.BodyOffsets[boneAIndex].Inverse to convert from joint space to body space. The result is
              // the joint position of B in body space of A.
              // To get AnchorPositionBLocal, we only have to apply the inverse offset.

              BallJoint joint = new BallJoint
              {
            BodyA = ragdoll.Bodies[parentIndex],
            BodyB = ragdoll.Bodies[childIndex],
            CollisionEnabled = false,
            AnchorPositionALocal = (ragdoll.BodyOffsets[parentIndex].Inverse * skeleton.GetBindPoseAbsoluteInverse(parentIndex) * skeleton.GetBindPoseAbsoluteInverse(childIndex).Inverse).Translation,
            AnchorPositionBLocal = ragdoll.BodyOffsets[childIndex].Inverse.Position,
            ErrorReduction = errorReduction,
            Softness = softness,
              };
              ragdoll.Joints[childIndex] = joint;
        }
        private static void AddTwistSwingLimit(Ragdoll ragdoll, Skeleton skeleton, AvatarBone parentBone, AvatarBone childBone, Matrix33F orientationA, Matrix33F orientationB, Vector3F minimum, Vector3F maximum)
        {
            int parentIndex = (int)parentBone;
              int childIndex = (int)childBone;

              // The difficult part is to define the constraint anchor orientation.
              // Here is how we do it:
              // When we look at the front side of an Avatar in bind pose, the x-axis is parallel
              // to the arms. y points up and z is normal to the those axes.
              //
              // To define orientationA/B:
              // The anchor x-axis is the twist axis. That means, this is already the correct axis
              // for the hands (wrist joints) and orientationA/B are therefore Matrix33F.Identity.
              // For the Head, the twist axis must point up. Therefore orientationA/B must be a 90°
              // rotation about z to rotate the twist axis up.
              // For the shoulder-elbow connection, orientationA is Matrix.Identity. The swing cone must
              // not be parallel to the arm axis (because the elbow cannot bend backwards). Therefore,
              // orientationB defines a rotation that rotates the twist axis (= swing cone center) to the
              // front.
              //
              // To define AnchorOrientationALocal/AnchorOrientationBLocal:
              // AnchorOrientationALocal must be a rotation matrix that transforms a vector from local
              // constraint anchor space to local body space of A.
              // orientationA defines the constraint anchor orientation in model space.
              // With jointPosesAbsolute[boneAIndex].Orientation.Transposed, we convert from model space
              // to joint space. With ragdoll.BodyOffsets[boneAIndex].Orientation.Transposed, we convert from joint
              // space to body space. The combined rotation matrix converts from constraint anchor space
              // to body space.

              var limit = new TwistSwingLimit
              {
            BodyA = ragdoll.Bodies[parentIndex],
            BodyB = ragdoll.Bodies[childIndex],
            AnchorOrientationALocal = ragdoll.BodyOffsets[parentIndex].Orientation.Transposed * skeleton.GetBindPoseAbsoluteInverse(parentIndex).Rotation.ToRotationMatrix33() * orientationA,
            AnchorOrientationBLocal = ragdoll.BodyOffsets[childIndex].Orientation.Transposed * skeleton.GetBindPoseAbsoluteInverse(childIndex).Rotation.ToRotationMatrix33() * orientationB,
            Minimum = minimum,
            Maximum = maximum,
            ErrorReduction = 0.2f,
            Softness = 0.001f
              };
              ragdoll.Limits[childIndex] = limit;
        }
        private static void AddAngularLimit(Ragdoll ragdoll, Skeleton skeleton, AvatarBone parentBone, AvatarBone childBone, Matrix33F orientationA, Matrix33F orientationB, Vector3F minimum, Vector3F maximum)
        {
            // Similar to AddTwistSwingLimit

              int parentIndex = (int)parentBone;
              int childIndex = (int)childBone;

              var limit = new AngularLimit
              {
            BodyA = ragdoll.Bodies[parentIndex],
            BodyB = ragdoll.Bodies[childIndex],
            AnchorOrientationALocal = ragdoll.BodyOffsets[parentIndex].Orientation.Transposed * skeleton.GetBindPoseAbsoluteInverse(parentIndex).Rotation.ToRotationMatrix33() * orientationA,
            AnchorOrientationBLocal = ragdoll.BodyOffsets[childIndex].Orientation.Transposed * skeleton.GetBindPoseAbsoluteInverse(childIndex).Rotation.ToRotationMatrix33() * orientationB,
            Minimum = minimum,
            Maximum = maximum,
            ErrorReduction = new Vector3F(0.2f),
            Softness = new Vector3F(0.001f)
              };
              ragdoll.Limits[childIndex] = limit;
        }