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); }