MultiBody CreateFeatherstoneMultiBody(MultiBodyDynamicsWorld world, int numLinks,
Vector3 basePosition, Vector3 baseHalfExtents, Vector3 linkHalfExtents, bool spherical, bool floating)
{
float mass = 1;
Vector3 inertia = Vector3.Zero;
if (mass != 0)
{
using (var box = new BoxShape(baseHalfExtents))
{
box.CalculateLocalInertia(mass, out inertia);
}
}
var mb = new MultiBody(numLinks, mass, inertia, !floating, false);
//body.HasSelfCollision = false;
//body.BaseVelocity = Vector3.Zero;
mb.BasePosition = basePosition;
//body.WorldToBaseRot = new Quaternion(0, 0, 1, -0.125f * (float)Math.PI);
mb.WorldToBaseRot = Quaternion.Identity;
float linkMass = 1;
Vector3 linkInertia = Vector3.Zero;
if (linkMass != 0)
{
using (var box = new BoxShape(linkHalfExtents))
{
box.CalculateLocalInertia(linkMass, out linkInertia);
}
}
//y-axis assumed up
Vector3 parentComToCurrentCom = new Vector3(0, -linkHalfExtents[1] * 2.0f, 0); //par body's COM to cur body's COM offset
Vector3 currentPivotToCurrentCom = new Vector3(0, -linkHalfExtents[1], 0); //cur body's COM to cur body's PIV offset
Vector3 parentComToCurrentPivot = parentComToCurrentCom - currentPivotToCurrentCom; //par body's COM to cur body's PIV offset
for (int i = 0; i < numLinks; i++)
{
if (spherical)
{
mb.SetupSpherical(i, linkMass, linkInertia, i - 1,
Quaternion.Identity, parentComToCurrentPivot, currentPivotToCurrentCom, false);
}
else
{
Vector3 hingeJointAxis = new Vector3(1, 0, 0);
mb.SetupRevolute(i, linkMass, linkInertia, i - 1,
Quaternion.Identity, hingeJointAxis, parentComToCurrentPivot, currentPivotToCurrentCom, false);
}
}
mb.FinalizeMultiDof();
(World as MultiBodyDynamicsWorld).AddMultiBody(mb);
return(mb);
}
void CreateOrConfigureMultiBody(ref MultiBody mb, float baseMass, BCollisionShape[] shapes, BMultiBodyConstraint[] constraints)
{
BulletSharp.Math.Vector3 inertia = BulletSharp.Math.Vector3.Zero;
if (baseMass != 0)
{
CollisionShape cs = m_baseCollisionShape.GetCollisionShape();
cs.CalculateLocalInertia(baseMass, out inertia);
}
mb = new MultiBody(m_links.Count, baseMass, inertia, fixedBase, canSleep);
mb.BasePosition = transform.position.ToBullet();
UnityEngine.Quaternion r = UnityEngine.Quaternion.Inverse(transform.rotation);
mb.WorldToBaseRot = r.ToBullet();
for (int i = 0; i < m_links.Count; i++)
{
//Debug.Log("Found link " + i + " parent " + m_links[i].parentIndex + " index " + m_links[i].index);
BMultiBodyLink link = m_links[i];
CollisionShape cs = shapes[i].GetCollisionShape();
if (cs != null)
{
cs.CalculateLocalInertia(link.mass, out inertia);
}
else
{
inertia = BulletSharp.Math.Vector3.Zero;
}
FeatherstoneJointType jt = link.jointType;
int parentIdx = link.parentIndex;
// Vector from parent pivot (COM) to the joint pivot point in parent's frame
UnityEngine.Vector3 parentCOM2ThisPivotOffset;
link.FreezeJointAxis();
if (link.parentIndex >= 0)
{
parentCOM2ThisPivotOffset = link.parentCOM2JointPivotOffset;
}
else
{
parentCOM2ThisPivotOffset = transform.InverseTransformPoint(link.transform.TransformPoint(link.localPivotPosition));
}
// Vector from the joint pivot point to link's pivot point (COM) in link's frame.
UnityEngine.Vector3 thisPivotToThisCOMOffset = link.thisPivotToJointCOMOffset;
// Should rotate vectors in parent frame to vectors in local frame
UnityEngine.Quaternion parentToThisRotation = link.parentToJointRotation;
switch (jt)
{
case FeatherstoneJointType.Fixed:
mb.SetupFixed(i, link.mass, inertia, link.parentIndex, parentToThisRotation.ToBullet(), parentCOM2ThisPivotOffset.ToBullet(), thisPivotToThisCOMOffset.ToBullet(), false);
break;
case FeatherstoneJointType.Planar:
mb.SetupPlanar(i, link.mass, inertia, link.parentIndex, parentToThisRotation.ToBullet(), link.rotationAxis.ToBullet(), thisPivotToThisCOMOffset.ToBullet(), false);
break;
case FeatherstoneJointType.Prismatic:
mb.SetupPrismatic(i, link.mass, inertia, link.parentIndex, parentToThisRotation.ToBullet(), link.rotationAxis.ToBullet(), parentCOM2ThisPivotOffset.ToBullet(), thisPivotToThisCOMOffset.ToBullet(), false);
break;
case FeatherstoneJointType.Revolute:
mb.SetupRevolute(i, link.mass, inertia, link.parentIndex, parentToThisRotation.ToBullet(), link.rotationAxis.ToBullet(), parentCOM2ThisPivotOffset.ToBullet(), thisPivotToThisCOMOffset.ToBullet(), false);
break;
case FeatherstoneJointType.Spherical:
mb.SetupSpherical(i, link.mass, inertia, link.parentIndex, parentToThisRotation.ToBullet(), parentCOM2ThisPivotOffset.ToBullet(), thisPivotToThisCOMOffset.ToBullet(), false);
break;
default:
Debug.LogError("Invalid joint type for link " + link.name);
break;
}
}
mb.CanSleep = true;
mb.HasSelfCollision = false;
mb.UseGyroTerm = true;
bool damping = true;
if (damping)
{
mb.LinearDamping = 0.1f;
mb.AngularDamping = 0.9f;
}
else
{
mb.LinearDamping = 0;
mb.AngularDamping = 0;
}
mb.FinalizeMultiDof();
m_multibody = mb;
}
//todo(erwincoumans) Quick hack, reference to InvertedPendulumPDControl implementation. Will create a separate header/source file for this.
public static MultiBody createInvertedPendulumMultiBody(float radius, MultiBodyDynamicsWorld world, Matrix baseWorldTrans, bool fixedBase)
{
BulletSharp.Math.Vector4[] colors = new BulletSharp.Math.Vector4[]
{
new BulletSharp.Math.Vector4(1, 0, 0, 1),
new BulletSharp.Math.Vector4(0, 1, 0, 1),
new BulletSharp.Math.Vector4(0, 1, 1, 1),
new BulletSharp.Math.Vector4(1, 1, 0, 1),
};
int curColor = 0;
bool damping = false;
bool gyro = false;
int numLinks = 2;
bool spherical = false; //set it ot false -to use 1DoF hinges instead of 3DoF sphericals
bool canSleep = false;
bool selfCollide = false;
BulletSharp.Math.Vector3 linkHalfExtents = new BulletSharp.Math.Vector3(0.05f, 0.37f, 0.1f);
BulletSharp.Math.Vector3 baseHalfExtents = new BulletSharp.Math.Vector3(0.04f, 0.35f, 0.08f);
//mbC.forceMultiDof(); //if !spherical, you can comment this line to check the 1DoF algorithm
//init the base
BulletSharp.Math.Vector3 baseInertiaDiag = new BulletSharp.Math.Vector3(0.0f, 0.0f, 0.0f);
float baseMass = fixedBase ? 0.0f : 10.0f;
if (baseMass != 0)
{
//CollisionShape *shape = new btSphereShape(baseHalfExtents[0]);// btBoxShape(BulletSharp.Math.Vector3(baseHalfExtents[0], baseHalfExtents[1], baseHalfExtents[2]));
CollisionShape shape = new BoxShape(new BulletSharp.Math.Vector3(baseHalfExtents[0], baseHalfExtents[1], baseHalfExtents[2]));
shape.CalculateLocalInertia(baseMass, out baseInertiaDiag);
shape.Dispose();
}
MultiBody pMultiBody = new MultiBody(numLinks, 0, baseInertiaDiag, fixedBase, canSleep);
pMultiBody.BaseWorldTransform = baseWorldTrans;
BulletSharp.Math.Vector3 vel = new BulletSharp.Math.Vector3(0, 0, 0);
// pMultiBody.setBaseVel(vel);
//init the links
BulletSharp.Math.Vector3 hingeJointAxis = new BulletSharp.Math.Vector3(1, 0, 0);
//y-axis assumed up
BulletSharp.Math.Vector3 parentComToCurrentCom = new BulletSharp.Math.Vector3(0, -linkHalfExtents[1] * 2.0f, 0); //par body's COM to cur body's COM offset
BulletSharp.Math.Vector3 currentPivotToCurrentCom = new BulletSharp.Math.Vector3(0, -linkHalfExtents[1], 0); //cur body's COM to cur body's PIV offset
BulletSharp.Math.Vector3 parentComToCurrentPivot = parentComToCurrentCom - currentPivotToCurrentCom; //par body's COM to cur body's PIV offset
//////
float q0 = 1.0f * Mathf.PI / 180.0f;
BulletSharp.Math.Quaternion quat0 = new BulletSharp.Math.Quaternion(new BulletSharp.Math.Vector3(1, 0, 0), q0);
quat0.Normalize();
/////
for (int i = 0; i < numLinks; ++i)
{
float linkMass = 1.0f;
//if (i==3 || i==2)
// linkMass= 1000;
BulletSharp.Math.Vector3 linkInertiaDiag = new BulletSharp.Math.Vector3(0.0f, 0.0f, 0.0f);
CollisionShape shape = null;
if (i == 0)
{
shape = new BoxShape(new BulletSharp.Math.Vector3(linkHalfExtents[0], linkHalfExtents[1], linkHalfExtents[2]));//
}
else
{
shape = new SphereShape(radius);
}
shape.CalculateLocalInertia(linkMass, out linkInertiaDiag);
shape.Dispose();
if (!spherical)
{
//pMultiBody.setupRevolute(i, linkMass, linkInertiaDiag, i - 1, BulletSharp.Math.Quaternion(0.f, 0.f, 0.f, 1.f), hingeJointAxis, parentComToCurrentPivot, currentPivotToCurrentCom, false);
if (i == 0)
{
pMultiBody.SetupRevolute(i, linkMass, linkInertiaDiag, i - 1,
new BulletSharp.Math.Quaternion(0.0f, 0.0f, 0.0f, 1.0f),
hingeJointAxis,
parentComToCurrentPivot,
currentPivotToCurrentCom, false);
}
else
{
parentComToCurrentCom = new BulletSharp.Math.Vector3(0, -radius * 2.0f, 0); //par body's COM to cur body's COM offset
currentPivotToCurrentCom = new BulletSharp.Math.Vector3(0, -radius, 0); //cur body's COM to cur body's PIV offset
parentComToCurrentPivot = parentComToCurrentCom - currentPivotToCurrentCom; //par body's COM to cur body's PIV offset
pMultiBody.SetupFixed(i, linkMass, linkInertiaDiag, i - 1,
new BulletSharp.Math.Quaternion(0.0f, 0.0f, 0.0f, 1.0f),
parentComToCurrentPivot,
currentPivotToCurrentCom);
}
}
else
{
//pMultiBody.setupPlanar(i, linkMass, linkInertiaDiag, i - 1, BulletSharp.Math.Quaternion(0.f, 0.f, 0.f, 1.f)/*quat0*/, BulletSharp.Math.Vector3(1, 0, 0), parentComToCurrentPivot*2, false);
pMultiBody.SetupSpherical(i, linkMass, linkInertiaDiag, i - 1, new BulletSharp.Math.Quaternion(0.0f, 0.0f, 0.0f, 1.0f), parentComToCurrentPivot, currentPivotToCurrentCom, false);
}
}
pMultiBody.FinalizeMultiDof();
world.AddMultiBody(pMultiBody);
MultiBody mbC = pMultiBody;
mbC.CanSleep = (canSleep);
mbC.HasSelfCollision = (selfCollide);
mbC.UseGyroTerm = (gyro);
//
if (!damping)
{
mbC.LinearDamping = (0.0f);
mbC.AngularDamping = (0.0f);
}
else
{
mbC.LinearDamping = (0.1f);
mbC.AngularDamping = (0.9f);
}
if (numLinks > 0)
{
q0 = 180.0f * Mathf.PI / 180.0f;
if (!spherical)
{
mbC.SetJointPosMultiDof(0, new float[] { q0 });
}
else
{
BulletSharp.Math.Vector3 vv = new BulletSharp.Math.Vector3(1, 1, 0);
vv.Normalize();
quat0 = new BulletSharp.Math.Quaternion(vv, q0);
quat0.Normalize();
float[] quat0fs = new float[] { quat0.X, quat0.Y, quat0.Z, quat0.W };
mbC.SetJointPosMultiDof(0, quat0fs);
}
}
///
BulletSharp.Math.Quaternion[] world_to_local; //btAlignedObjectArray<BulletSharp.Math.Quaternion>
world_to_local = new BulletSharp.Math.Quaternion[pMultiBody.NumLinks + 1];
BulletSharp.Math.Vector3[] local_origin; //btAlignedObjectArray<BulletSharp.Math.Vector3>
local_origin = new BulletSharp.Math.Vector3[pMultiBody.NumLinks + 1];
world_to_local[0] = pMultiBody.WorldToBaseRot;
local_origin[0] = pMultiBody.BasePosition;
// double friction = 1;
{
if (true)
{
CollisionShape shape = new BoxShape(new BulletSharp.Math.Vector3(baseHalfExtents[0], baseHalfExtents[1], baseHalfExtents[2])); //new btSphereShape(baseHalfExtents[0]);
// guiHelper.createCollisionShapeGraphicsObject(shape);
MultiBodyLinkCollider col = new MultiBodyLinkCollider(pMultiBody, -1);
col.CollisionShape = shape;
Matrix tr = new Matrix();
tr.ScaleVector = BulletSharp.Math.Vector3.One;
//if we don't set the initial pose of the btCollisionObject, the simulator will do this
//when syncing the btMultiBody link transforms to the btMultiBodyLinkCollider
tr.Origin = local_origin[0];
BulletSharp.Math.Quaternion orn = new BulletSharp.Math.Quaternion(new BulletSharp.Math.Vector3(0, 0, 1), 0.25f * 3.1415926538f);
tr.Rotation = (orn);
col.WorldTransform = (tr);
bool isDynamic = (baseMass > 0 && !fixedBase);
CollisionFilterGroups collisionFilterGroup = isDynamic ? CollisionFilterGroups.DefaultFilter : CollisionFilterGroups.StaticFilter;
CollisionFilterGroups collisionFilterMask = isDynamic ? CollisionFilterGroups.AllFilter : CollisionFilterGroups.AllFilter ^ CollisionFilterGroups.StaticFilter;
world.AddCollisionObject(col, collisionFilterGroup, collisionFilterMask);//, 2,1+2);
BulletSharp.Math.Vector4 color = new BulletSharp.Math.Vector4(0.0f, 0.0f, 0.5f, 1f);
//guiHelper.createCollisionObjectGraphicsObject(col, color);
// col.setFriction(friction);
pMultiBody.BaseCollider = (col);
}
}
for (int i = 0; i < pMultiBody.NumLinks; ++i)
{
int parent = pMultiBody.GetParent(i);
world_to_local[i + 1] = pMultiBody.GetParentToLocalRot(i) * world_to_local[parent + 1];
BulletSharp.Math.Vector3 vv = world_to_local[i + 1].Inverse.Rotate(pMultiBody.GetRVector(i));
local_origin[i + 1] = local_origin[parent + 1] + vv;
}
for (int i = 0; i < pMultiBody.NumLinks; ++i)
{
BulletSharp.Math.Vector3 posr = local_origin[i + 1];
// float pos[4]={posr.x(),posr.y(),posr.z(),1};
float[] quat = new float[] { -world_to_local[i + 1].X, -world_to_local[i + 1].Y, -world_to_local[i + 1].Z, world_to_local[i + 1].W };
CollisionShape shape = null;
if (i == 0)
{
shape = new BoxShape(new BulletSharp.Math.Vector3(linkHalfExtents[0], linkHalfExtents[1], linkHalfExtents[2]));//btSphereShape(linkHalfExtents[0]);
}
else
{
shape = new SphereShape(radius);
}
//guiHelper.createCollisionShapeGraphicsObject(shape);
MultiBodyLinkCollider col = new MultiBodyLinkCollider(pMultiBody, i);
col.CollisionShape = (shape);
Matrix tr = new Matrix();
tr.ScaleVector = new BulletSharp.Math.Vector3();
tr.Origin = (posr);
tr.Rotation = (new BulletSharp.Math.Quaternion(quat[0], quat[1], quat[2], quat[3]));
col.WorldTransform = (tr);
// col.setFriction(friction);
bool isDynamic = true;//(linkMass > 0);
CollisionFilterGroups collisionFilterGroup = isDynamic ? CollisionFilterGroups.DefaultFilter : CollisionFilterGroups.StaticFilter;
CollisionFilterGroups collisionFilterMask = isDynamic ? CollisionFilterGroups.AllFilter : CollisionFilterGroups.AllFilter ^ CollisionFilterGroups.StaticFilter;
//if (i==0||i>numLinks-2)
{
world.AddCollisionObject(col, collisionFilterGroup, collisionFilterMask);//,2,1+2);
BulletSharp.Math.Vector4 color = colors[curColor];
curColor++;
curColor &= 3;
//guiHelper.createCollisionObjectGraphicsObject(col, color);
pMultiBody.GetLink(i).Collider = col;
}
}
return(pMultiBody);
}