private void AddAxisLockConstraint()
{
if (LockAxisConstraint == null)
{
// Lock that axis by creating a 6DOF constraint that has one end in the world and
// the other in the object.
// http://www.bulletphysics.org/Bullet/phpBB3/viewtopic.php?p=20817
// http://www.bulletphysics.org/Bullet/phpBB3/viewtopic.php?p=26380
// Remove any existing axis constraint (just to be sure)
RemoveAxisLockConstraint();
BSConstraint6Dof axisConstrainer = new BSConstraint6Dof(m_physicsScene.World, m_controllingPrim.PhysBody,
OMV.Vector3.Zero, OMV.Quaternion.Identity,
false, true);
LockAxisConstraint = axisConstrainer;
m_physicsScene.Constraints.AddConstraint(LockAxisConstraint);
// The constraint is tied to the world and oriented to the prim.
// Free to move linearly in the region
OMV.Vector3 linearLow = OMV.Vector3.Zero;
OMV.Vector3 linearHigh = m_physicsScene.TerrainManager.WorldMax;
axisConstrainer.SetLinearLimits(linearLow, linearHigh);
// Angular with some axis locked
float fPI = (float)Math.PI;
OMV.Vector3 angularLow = new OMV.Vector3(-fPI, -fPI, -fPI);
OMV.Vector3 angularHigh = new OMV.Vector3(fPI, fPI, fPI);
if (m_controllingPrim.LockedAxis.X != 1f)
{
angularLow.X = 0f;
angularHigh.X = 0f;
}
if (m_controllingPrim.LockedAxis.Y != 1f)
{
angularLow.Y = 0f;
angularHigh.Y = 0f;
}
if (m_controllingPrim.LockedAxis.Z != 1f)
{
angularLow.Z = 0f;
angularHigh.Z = 0f;
}
if (!axisConstrainer.SetAngularLimits(angularLow, angularHigh))
{
m_physicsScene.DetailLog("{0},BSActorLockAxis.AddAxisLockConstraint,failedSetAngularLimits", m_controllingPrim.LocalID);
}
m_physicsScene.DetailLog("{0},BSActorLockAxis.AddAxisLockConstraint,create,linLow={1},linHi={2},angLow={3},angHi={4}",
m_controllingPrim.LocalID, linearLow, linearHigh, angularLow, angularHigh);
// Constants from one of the posts mentioned above and used in Bullet's ConstraintDemo.
axisConstrainer.TranslationalLimitMotor(true, 5.0f, 0.1f);
axisConstrainer.RecomputeConstraintVariables(m_controllingPrim.RawMass);
}
}
private BSConstraint BuildConstraint(BSPrimLinkable rootPrim, BSPrimLinkable childPrim)
{
// Zero motion for children so they don't interpolate
childPrim.ZeroMotion(true);
// Relative position normalized to the root prim
// Essentually a vector pointing from center of rootPrim to center of childPrim
OMV.Vector3 childRelativePosition = childPrim.Position - rootPrim.Position;
// real world coordinate of midpoint between the two objects
OMV.Vector3 midPoint = rootPrim.Position + (childRelativePosition / 2);
DetailLog("{0},BSLinksetConstraint.BuildConstraint,taint,root={1},rBody={2},child={3},cBody={4},rLoc={5},cLoc={6},midLoc={7}",
rootPrim.LocalID,
rootPrim.LocalID, rootPrim.PhysBody.AddrString,
childPrim.LocalID, childPrim.PhysBody.AddrString,
rootPrim.Position, childPrim.Position, midPoint);
// create a constraint that allows no freedom of movement between the two objects
// http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?t=4818
BSConstraint6Dof constrain = new BSConstraint6Dof(
PhysicsScene.World, rootPrim.PhysBody, childPrim.PhysBody, midPoint, true, true);
PhysicsScene.Constraints.AddConstraint(constrain);
// zero linear and angular limits makes the objects unable to move in relation to each other
constrain.SetLinearLimits(OMV.Vector3.Zero, OMV.Vector3.Zero);
constrain.SetAngularLimits(OMV.Vector3.Zero, OMV.Vector3.Zero);
// tweek the constraint to increase stability
constrain.UseFrameOffset(BSParam.LinkConstraintUseFrameOffset);
constrain.TranslationalLimitMotor(BSParam.LinkConstraintEnableTransMotor,
BSParam.LinkConstraintTransMotorMaxVel,
BSParam.LinkConstraintTransMotorMaxForce);
constrain.SetCFMAndERP(BSParam.LinkConstraintCFM, BSParam.LinkConstraintERP);
if (BSParam.LinkConstraintSolverIterations != 0f)
{
constrain.SetSolverIterations(BSParam.LinkConstraintSolverIterations);
}
return(constrain);
}
