//--------------------------------------------------------------
#region Creation & Cleanup
//--------------------------------------------------------------
public VehicleObject(IServiceLocator services)
{
_services = services;
Name = "Vehicle";
_inputService = _services.GetInstance<IInputService>();
_simulation = _services.GetInstance<Simulation>();
// Load models for rendering.
var contentManager = _services.GetInstance<ContentManager>();
_vehicleModelNode = contentManager.Load<ModelNode>("Car/Car").Clone();
_wheelModelNodes = new ModelNode[4];
_wheelModelNodes[0] = contentManager.Load<ModelNode>("Car/Wheel").Clone();
_wheelModelNodes[1] = _wheelModelNodes[0].Clone();
_wheelModelNodes[2] = _wheelModelNodes[0].Clone();
_wheelModelNodes[3] = _wheelModelNodes[0].Clone();
// Add wheels under the car model node.
_vehicleModelNode.Children.Add(_wheelModelNodes[0]);
_vehicleModelNode.Children.Add(_wheelModelNodes[1]);
_vehicleModelNode.Children.Add(_wheelModelNodes[2]);
_vehicleModelNode.Children.Add(_wheelModelNodes[3]);
// ----- Create the chassis of the car.
// The Vehicle needs a rigid body that represents the chassis. This can be any shape (e.g.
// a simple BoxShape). In this example we will build a convex polyhedron from the car model.
// 1. Extract the vertices from the car model.
// The car model has ~10,000 vertices. It consists of a MeshNode for the glass
// parts and a MeshNode "Car" for the chassis.
var meshNode = _vehicleModelNode.GetDescendants()
.OfType<MeshNode>()
.First(mn => mn.Name == "Car");
var mesh = MeshHelper.ToTriangleMesh(meshNode.Mesh);
// Apply the transformation of the mesh node.
mesh.Transform(meshNode.PoseWorld * Matrix44F.CreateScale(meshNode.ScaleWorld));
// 2. (Optional) Create simplified convex hull from mesh.
// We could also skip this step and directly create a convex polyhedron from the mesh using
// var chassisShape = new ConvexPolyhedron(mesh.Vertices);
// However, the convex polyhedron would still have 500-600 vertices.
// We can reduce the number of vertices by using the GeometryHelper.
// Create a convex hull for mesh with max. 64 vertices. Additional, shrink the hull by 4 cm.
var convexHull = GeometryHelper.CreateConvexHull(mesh.Vertices, 64, -0.04f);
// 3. Create convex polyhedron shape using the vertices of the convex hull.
var chassisShape = new ConvexPolyhedron(convexHull.Vertices.Select(v => v.Position));
// (Note: Building convex hulls and convex polyhedra are time-consuming. To save loading time
// we should build the shape in the XNA content pipeline. See other DigitalRune Physics
// Samples.)
// The mass properties of the car. We use a mass of 800 kg.
var mass = MassFrame.FromShapeAndMass(chassisShape, Vector3F.One, 800, 0.1f, 1);
// Trick: We artificially modify the center of mass of the rigid body. Lowering the center
// of mass makes the car more stable against rolling in tight curves.
// We could also modify mass.Inertia for other effects.
var pose = mass.Pose;
pose.Position.Y -= 0.5f; // Lower the center of mass.
pose.Position.Z = -0.5f; // The center should be below the driver.
// (Note: The car model is not exactly centered.)
mass.Pose = pose;
// Material for the chassis.
var material = new UniformMaterial
{
Restitution = 0.1f,
StaticFriction = 0.2f,
DynamicFriction = 0.2f
};
var chassis = new RigidBody(chassisShape, mass, material)
{
Pose = new Pose(new Vector3F(0, 2, 0)), // Start position
UserData = "NoDraw", // (Remove this line to render the collision model.)
};
// ----- Create the vehicle.
Vehicle = new Vehicle(_simulation, chassis);
// Add 4 wheels.
Vehicle.Wheels.Add(new Wheel { Offset = new Vector3F(-0.9f, 0.6f, -2.0f), Radius = 0.36f, SuspensionRestLength = 0.55f, MinSuspensionLength = 0.25f, Friction = 2 }); // Front left
Vehicle.Wheels.Add(new Wheel { Offset = new Vector3F(0.9f, 0.6f, -2.0f), Radius = 0.36f, SuspensionRestLength = 0.55f, MinSuspensionLength = 0.25f, Friction = 2 }); // Front right
Vehicle.Wheels.Add(new Wheel { Offset = new Vector3F(-0.9f, 0.6f, 0.98f), Radius = 0.36f, SuspensionRestLength = 0.55f, MinSuspensionLength = 0.25f, Friction = 1.8f });// Back left
Vehicle.Wheels.Add(new Wheel { Offset = new Vector3F(0.9f, 0.6f, 0.98f), Radius = 0.36f, SuspensionRestLength = 0.55f, MinSuspensionLength = 0.25f, Friction = 1.8f }); // Back right
// Vehicles are disabled per default. This way we can create the vehicle and the simulation
// objects are only added when needed.
Vehicle.Enabled = false;
}
//--------------------------------------------------------------
/// <summary>
/// Initializes a new instance of the <see cref="VehicleForceEffect"/> class.
/// </summary>
/// <param name="vehicle">The vehicle.</param>
internal VehicleForceEffect(Vehicle vehicle)
{
Debug.Assert(vehicle != null);
Vehicle = vehicle;
}
