public ConstraintSample3(Microsoft.Xna.Framework.Game game)
: base(game)
{
// Add basic force effects.
Simulation.ForceEffects.Add(new Gravity());
Simulation.ForceEffects.Add(new Damping());
// Add a ground plane.
RigidBody groundPlane = new RigidBody(new PlaneShape(Vector3F.UnitY, 0))
{
Name = "GroundPlane", // Names are not required but helpful for debugging.
MotionType = MotionType.Static,
};
Simulation.RigidBodies.Add(groundPlane);
// ----- HingeJoint with AngularVelocityMotor
// A board is fixed on a pole like a wind wheel.
// An AngularVelocityMotor creates a rotation with constant angular velocity around the
// hinge axis.
RigidBody box0 = new RigidBody(new BoxShape(0.1f, 2f, 0.1f))
{
Pose = new Pose(new Vector3F(-2, 1, 0)),
MotionType = MotionType.Static,
};
Simulation.RigidBodies.Add(box0);
RigidBody box1 = new RigidBody(new BoxShape(0.1f, 0.4f, 1f))
{
Pose = new Pose(new Vector3F(-2 + 0.05f, 1.8f, 0))
};
Simulation.RigidBodies.Add(box1);
HingeJoint hingeJoint = new HingeJoint
{
BodyA = box0,
BodyB = box1,
AnchorPoseALocal = new Pose(new Vector3F(0.05f, 0.8f, 0)),
AnchorPoseBLocal = new Pose(new Vector3F(-0.05f, 0, 0)),
CollisionEnabled = false,
};
Simulation.Constraints.Add(hingeJoint);
AngularVelocityMotor angularVelocityMotor = new AngularVelocityMotor
{
BodyA = box0,
// The rotation axis is the local x axis of BodyA.
AxisALocal = Vector3F.UnitX,
BodyB = box1,
TargetVelocity = 10,
// The motor power is limit, so that the rotation can be stopped by other objects blocking
// the movement.
MaxForce = 10000,
// The HingeJoint controls all other axes. So this motor must only act on the hinge
// axis.
UseSingleAxisMode = true,
CollisionEnabled = false,
};
Simulation.Constraints.Add(angularVelocityMotor);
// ----- A PrismaticJoint with a LinearVelocityMotor.
RigidBody box2 = new RigidBody(new BoxShape(0.7f, 0.7f, 0.7f))
{
Pose = new Pose(new Vector3F(0, 2, 0)),
MotionType = MotionType.Static,
};
Simulation.RigidBodies.Add(box2);
RigidBody box3 = new RigidBody(new BoxShape(0.5f, 1.5f, 0.5f))
{
Pose = new Pose(new Vector3F(0, 1, 0))
};
Simulation.RigidBodies.Add(box3);
_prismaticJoint = new PrismaticJoint
{
BodyA = box2,
BodyB = box3,
AnchorPoseALocal = new Pose(new Vector3F(0, 0, 0), new Matrix33F(0, 1, 0,
-1, 0, 0,
0, 0, 1)),
AnchorPoseBLocal = new Pose(new Vector3F(0, 0, 0), new Matrix33F(0, 1, 0,
-1, 0, 0,
0, 0, 1)),
CollisionEnabled = false,
};
Simulation.Constraints.Add(_prismaticJoint);
_linearVelocityMotor = new LinearVelocityMotor
{
BodyA = box2,
AxisALocal = -Vector3F.UnitY,
BodyB = box3,
TargetVelocity = 1,
CollisionEnabled = false,
MaxForce = 10000,
UseSingleAxisMode = true,
};
Simulation.Constraints.Add(_linearVelocityMotor);
// ----- A BallJoint with a TwistSwingLimit and a QuaternionMotor
// The ball joint connects a cylinder to a static box.
// The twist-swing limits rotational movement.
// The quaternion motor acts like a spring that controls the angle of joint.
RigidBody box4 = new RigidBody(new BoxShape(0.5f, 0.5f, 0.5f))
{
Pose = new Pose(new Vector3F(2, 2, 0)),
MotionType = MotionType.Static,
};
Simulation.RigidBodies.Add(box4);
RigidBody cylinder0 = new RigidBody(new CylinderShape(0.1f, 0.75f))
{
Pose = new Pose(new Vector3F(2, 2 - 0.75f / 2 - 0.25f, 0))
};
Simulation.RigidBodies.Add(cylinder0);
_ballJoint = new BallJoint
{
BodyA = box4,
BodyB = cylinder0,
AnchorPositionALocal = new Vector3F(0, -0.25f, 0),
AnchorPositionBLocal = new Vector3F(0, 0.75f / 2, 0),
CollisionEnabled = false,
};
Simulation.Constraints.Add(_ballJoint);
_twistSwingLimit = new TwistSwingLimit
{
BodyA = box4,
// The first column is the twist axis (-y). The other two columns are the swing axes.
AnchorOrientationALocal = new Matrix33F(0, 1, 0,
-1, 0, 0,
0, 0, 1),
BodyB = cylinder0,
AnchorOrientationBLocal = new Matrix33F(0, 1, 0,
-1, 0, 0,
0, 0, 1),
CollisionEnabled = false,
// The twist is limited to +/- 10°. The swing limits are +/- 40° and +/- 60°. This creates
// a deformed cone that limits the swing movements (see visualization).
Minimum = new Vector3F(-MathHelper.ToRadians(10), -MathHelper.ToRadians(40), -MathHelper.ToRadians(60)),
Maximum = new Vector3F(MathHelper.ToRadians(10), MathHelper.ToRadians(40), MathHelper.ToRadians(60)),
};
Simulation.Constraints.Add(_twistSwingLimit);
QuaternionMotor quaternionMotor = new QuaternionMotor
{
BodyA = box4,
AnchorOrientationALocal = Matrix33F.Identity,
BodyB = cylinder0,
AnchorOrientationBLocal = Matrix33F.Identity,
CollisionEnabled = false,
// The QuaternionMotor controls the orientation of the second body relative to the first
// body. Here, we define that the cylinder should swing 30° away from the default
// orientation.
TargetOrientation = QuaternionF.CreateRotationZ(MathHelper.ToRadians(30)),
// Position and orientation motors are similar to damped-springs. We can control
// the stiffness and damping of the spring. (It is also possible to set the SpringConstant
// to 0 if the QuaternionMotor should only act as a rotational damping.)
SpringConstant = 100,
DampingConstant = 20,
};
Simulation.Constraints.Add(quaternionMotor);
}
//--------------------------------------------------------------
/// <summary>
/// Initializes a new instance of the <see cref="RagdollMotor"/> class.
/// </summary>
/// <param name="boneIndex">The index of the controlled bone.</param>
/// <param name="parentIndex">
/// The index of the parent bone to which the controlled bone is connected.
/// (Only relevant for constraint motors.)
/// </param>
/// <exception cref="ArgumentOutOfRangeException">
/// <paramref name="boneIndex"/> is negative.
/// </exception>
public RagdollMotor(int boneIndex, int parentIndex)
{
if (boneIndex < 0)
throw new ArgumentOutOfRangeException("boneIndex", "boneIndex must not be negative.");
_boneIndex = boneIndex;
_parentIndex = parentIndex;
_quaternionMotor = new QuaternionMotor
{
DampingConstant = 1000000,
SpringConstant = 10000000,
MaxForce = float.PositiveInfinity,
AnchorOrientationALocal = Matrix33F.Identity,
AnchorOrientationBLocal = Matrix33F.Identity,
// Single-axis mode is faster but less stable. In single-axis mode, 1 DOF (degree of
// freedom) constraint is applied along the rotation axis. If single-axis mode is turned
// off, a 3 DOF is applied: The bones rotate around the rotation axis and 2 more constraints
// stabilize the bone in the 2 axes orthogonal to the rotation axis.
UseSingleAxisMode = false,
};
}
