MultiBody CreateFeatherstoneMultiBody(MultiBodyDynamicsWorld world, MultiBodySettings settings)
{
int nLinks = settings.NumLinks;
float mass = 13.5f * Scaling;
Vector3 inertia = new Vector3(91, 344, 253) * Scaling * Scaling;
var body = new MultiBody(nLinks, mass, inertia, settings.IsFixedBase, settings.CanSleep);
//body.HasSelfCollision = false;
//Quaternion orn = new Quaternion(0, 0, 1, -0.125f * Math.PI);
Quaternion orn = new Quaternion(0, 0, 0, 1);
body.BasePosition = settings.BasePosition;
body.WorldToBaseRot = orn;
body.BaseVelocity = Vector3.Zero;
Vector3 joint_axis_hinge = new Vector3(1, 0, 0);
Vector3 joint_axis_prismatic = new Vector3(0, 0, 1);
Quaternion parent_to_child = orn.Inverse();
Vector3 joint_axis_child_prismatic = parent_to_child.Rotate(joint_axis_prismatic);
Vector3 joint_axis_child_hinge = parent_to_child.Rotate(joint_axis_hinge);
int this_link_num = -1;
int link_num_counter = 0;
Vector3 pos = new Vector3(0, 0, 9.0500002f) * Scaling;
Vector3 joint_axis_position = new Vector3(0, 0, 4.5250001f) * Scaling;
for (int i = 0; i < nLinks; i++)
{
float initial_joint_angle = 0.3f;
if (i > 0)
initial_joint_angle = -0.06f;
int child_link_num = link_num_counter++;
if (settings.UsePrismatic) // i == (nLinks - 1))
{
body.SetupPrismatic(child_link_num, mass, inertia, this_link_num,
parent_to_child, joint_axis_child_prismatic, parent_to_child.Rotate(pos), Vector3.Zero, settings.DisableParentCollision);
}
else
{
body.SetupRevolute(child_link_num, mass, inertia, this_link_num,
parent_to_child, joint_axis_child_hinge, joint_axis_position, parent_to_child.Rotate(pos - joint_axis_position), settings.DisableParentCollision);
}
body.SetJointPos(child_link_num, initial_joint_angle);
this_link_num = i;
/*if (false) //!useGroundShape && i == 4)
{
Vector3 pivotInAworld = new Vector3(0, 20, 46);
Vector3 pivotInAlocal = body.WorldPosToLocal(i, pivotInAworld);
Vector3 pivotInBworld = pivotInAworld;
MultiBodyPoint2Point p2p = new MultiBodyPoint2Point(body, i, TypedConstraint.FixedBody, pivotInAlocal, pivotInBworld);
(World as MultiBodyDynamicsWorld).AddMultiBodyConstraint(p2p);
}*/
if (settings.UsePrismatic)
{
//MultiBodyConstraint con = new MultiBodyJointLimitConstraint(body, nLinks - 1, 2, 3);
if (settings.CreateConstraints)
{
MultiBodyConstraint con = new MultiBodyJointLimitConstraint(body, i, -1, 1);
(World as MultiBodyDynamicsWorld).AddMultiBodyConstraint(con);
}
}
else
{
//if (true)
{
var con = new MultiBodyJointMotor(body, i, 0, 50000);
(World as MultiBodyDynamicsWorld).AddMultiBodyConstraint(con);
}
var con2 = new MultiBodyJointLimitConstraint(body, i, -1, 1);
(World as MultiBodyDynamicsWorld).AddMultiBodyConstraint(con2);
}
}
// Add a collider for the base
Quaternion[] worldToLocal = new Quaternion[nLinks + 1];
Vector3[] localOrigin = new Vector3[nLinks + 1];
worldToLocal[0] = body.WorldToBaseRot;
localOrigin[0] = body.BasePosition;
//Vector3 halfExtents = new Vector3(7.5f, 0.05f, 4.5f);
Vector3 halfExtents = new Vector3(7.5f, 0.45f, 4.5f);
float[] posB = new float[] { localOrigin[0].X, localOrigin[0].Y, localOrigin[0].Z, 1 };
//float[] quatB = new float[] { worldToLocal[0].X, worldToLocal[0].Y, worldToLocal[0].Z, worldToLocal[0].W };
//if (true)
{
CollisionShape box = new BoxShape(halfExtents * Scaling);
var bodyInfo = new RigidBodyConstructionInfo(mass, null, box, inertia);
RigidBody bodyB = new RigidBody(bodyInfo);
var collider = new MultiBodyLinkCollider(body, -1);
collider.CollisionShape = box;
Matrix tr = Matrix.RotationQuaternion(worldToLocal[0].Inverse()) * Matrix.Translation(localOrigin[0]);
collider.WorldTransform = tr;
bodyB.WorldTransform = tr;
World.AddCollisionObject(collider, CollisionFilterGroups.StaticFilter,
CollisionFilterGroups.DefaultFilter | CollisionFilterGroups.StaticFilter);
collider.Friction = Friction;
body.BaseCollider = collider;
}
for (int i = 0; i < body.NumLinks; i++)
{
int parent = body.GetParent(i);
worldToLocal[i + 1] = body.GetParentToLocalRot(i) * worldToLocal[parent + 1];
localOrigin[i + 1] = localOrigin[parent + 1] + (worldToLocal[i + 1].Inverse().Rotate(body.GetRVector(i)));
}
for (int i = 0; i < body.NumLinks; i++)
{
CollisionShape box = new BoxShape(halfExtents * Scaling);
var collider = new MultiBodyLinkCollider(body, i);
collider.CollisionShape = box;
Matrix tr = Matrix.RotationQuaternion(worldToLocal[i + 1].Inverse()) * Matrix.Translation(localOrigin[i + 1]);
collider.WorldTransform = tr;
World.AddCollisionObject(collider, CollisionFilterGroups.StaticFilter,
CollisionFilterGroups.DefaultFilter | CollisionFilterGroups.StaticFilter);
collider.Friction = Friction;
body.GetLink(i).Collider = collider;
//World.DebugDrawer.DrawBox(halfExtents, pos, quat);
}
(World as MultiBodyDynamicsWorld).AddMultiBody(body);
return body;
}
protected override void OnInitializePhysics()
{
// collision configuration contains default setup for memory, collision setup
CollisionConf = new DefaultCollisionConfiguration();
Dispatcher = new CollisionDispatcher(CollisionConf);
Broadphase = new DbvtBroadphase();
Solver = new MultiBodyConstraintSolver();
World = new MultiBodyDynamicsWorld(Dispatcher, Broadphase, Solver as MultiBodyConstraintSolver, CollisionConf);
World.Gravity = new Vector3(0, -9.81f, 0);
const bool floating = false;
const bool gyro = false;
const int numLinks = 1;
const bool canSleep = false;
const bool selfCollide = false;
Vector3 linkHalfExtents = new Vector3(0.05f, 0.5f, 0.1f);
Vector3 baseHalfExtents = new Vector3(0.05f, 0.5f, 0.1f);
Vector3 baseInertiaDiag = Vector3.Zero;
const float baseMass = 0;
multiBody = new MultiBody(numLinks, baseMass, baseInertiaDiag, !floating, canSleep);
//multiBody.UseRK4Integration = true;
//multiBody.BaseWorldTransform = Matrix.Identity;
//init the links
Vector3 hingeJointAxis = new Vector3(1, 0, 0);
//y-axis assumed up
Vector3 parentComToCurrentCom = new Vector3(0, -linkHalfExtents[1], 0);
Vector3 currentPivotToCurrentCom = new Vector3(0, -linkHalfExtents[1], 0);
Vector3 parentComToCurrentPivot = parentComToCurrentCom - currentPivotToCurrentCom;
for(int i = 0; i < numLinks; i++)
{
const float linkMass = 10;
Vector3 linkInertiaDiag = Vector3.Zero;
using (var shape = new SphereShape(radius))
{
shape.CalculateLocalInertia(linkMass, out linkInertiaDiag);
}
multiBody.SetupRevolute(i, linkMass, linkInertiaDiag, i - 1, Quaternion.Identity,
hingeJointAxis, parentComToCurrentPivot, currentPivotToCurrentCom, false);
}
multiBody.FinalizeMultiDof();
(World as MultiBodyDynamicsWorld).AddMultiBody(multiBody);
multiBody.CanSleep = canSleep;
multiBody.HasSelfCollision = selfCollide;
multiBody.UseGyroTerm = gyro;
#if PENDULUM_DAMPING
multiBody.LinearDamping = 0.1f;
multiBody.AngularDamping = 0.9f;
#else
multiBody.LinearDamping = 0;
multiBody.AngularDamping = 0;
#endif
for (int i = 0; i < numLinks; i++)
{
var shape = new SphereShape(radius);
CollisionShapes.Add(shape);
var col = new MultiBodyLinkCollider(multiBody, i);
col.CollisionShape = shape;
const bool isDynamic = true;
CollisionFilterGroups collisionFilterGroup = isDynamic ? CollisionFilterGroups.DefaultFilter : CollisionFilterGroups.StaticFilter;
CollisionFilterGroups collisionFilterMask = isDynamic ? CollisionFilterGroups.AllFilter : CollisionFilterGroups.AllFilter & ~CollisionFilterGroups.StaticFilter;
World.AddCollisionObject(col, collisionFilterGroup, collisionFilterMask);
multiBody.GetLink(i).Collider = col;
}
}
void AddColliders(MultiBody multiBody, Vector3 baseHalfExtents, Vector3 linkHalfExtents)
{
// Add a collider for the base
Quaternion[] worldToLocal = new Quaternion[multiBody.NumLinks + 1];
Vector3[] localOrigin = new Vector3[multiBody.NumLinks + 1];
worldToLocal[0] = multiBody.WorldToBaseRot;
localOrigin[0] = multiBody.BasePosition;
//if (true)
{
var collider = new MultiBodyLinkCollider(multiBody, -1);
collider.CollisionShape = new BoxShape(baseHalfExtents);
Matrix tr = Matrix.RotationQuaternion(worldToLocal[0].Inverse());
tr.Origin = localOrigin[0];
collider.WorldTransform = tr;
World.AddCollisionObject(collider, CollisionFilterGroups.StaticFilter,
CollisionFilterGroups.DefaultFilter | CollisionFilterGroups.StaticFilter);
collider.Friction = Friction;
multiBody.BaseCollider = collider;
}
for (int i = 0; i < multiBody.NumLinks; i++)
{
int parent = multiBody.GetParent(i);
worldToLocal[i + 1] = multiBody.GetParentToLocalRot(i) * worldToLocal[parent + 1];
localOrigin[i + 1] = localOrigin[parent + 1] + (worldToLocal[i + 1].Inverse().Rotate(multiBody.GetRVector(i)));
}
for (int i = 0; i < multiBody.NumLinks; i++)
{
var collider = new MultiBodyLinkCollider(multiBody, i);
collider.CollisionShape = new BoxShape(linkHalfExtents);
Matrix tr = Matrix.RotationQuaternion(worldToLocal[i + 1].Inverse()) * Matrix.Translation(localOrigin[i + 1]);
collider.WorldTransform = tr;
World.AddCollisionObject(collider, CollisionFilterGroups.StaticFilter,
CollisionFilterGroups.DefaultFilter | CollisionFilterGroups.StaticFilter);
collider.Friction = Friction;
multiBody.GetLink(i).Collider = collider;
}
}
public void CreateUnityMultiBodyLinkColliderProxy(MultiBodyLinkCollider body)
{
GameObject cube = Instantiate<GameObject>(cubePrefab);
CollisionShape cs = body.CollisionShape;
if (cs is BoxShape) {
BoxShape bxcs = cs as BoxShape;
BulletSharp.Math.Vector3 s = bxcs.HalfExtentsWithMargin;
MeshRenderer mr = cube.GetComponentInChildren<MeshRenderer>();
mr.transform.localScale = s.ToUnity() * 2f;
Matrix4x4 m = body.WorldTransform.ToUnity();
cube.transform.position = BSExtensionMethods2.ExtractTranslationFromMatrix(ref m);
cube.transform.rotation = BSExtensionMethods2.ExtractRotationFromMatrix(ref m);
cube.transform.localScale = BSExtensionMethods2.ExtractScaleFromMatrix(ref m);
Destroy(cube.GetComponent<BulletRigidBodyProxy>());
BulletMultiBodyLinkColliderProxy cp = cube.AddComponent<BulletMultiBodyLinkColliderProxy>();
cp.target = body;
} else {
Debug.LogError("Not implemented");
}
}
