public CustomGravitySample(Microsoft.Xna.Framework.Game game)
: base(game)
{
// Add basic force effects.
Simulation.ForceEffects.Add(new CustomGravity());
Simulation.ForceEffects.Add(new Damping());
// Add a static sphere that represents the planet.
RigidBody planet = new RigidBody(new SphereShape(5))
{
MotionType = MotionType.Static,
};
Simulation.RigidBodies.Add(planet);
// ----- Add a few cylinder and sphere bodies at random positions above the planet.
Shape cylinderShape = new CylinderShape(0.3f, 1);
for (int i = 0; i < 10; i++)
{
// A random position 10 m above the planet center.
Vector3F randomPosition = RandomHelper.Random.NextVector3F(-1, 1);
randomPosition.Length = 10;
RigidBody body = new RigidBody(cylinderShape)
{
Pose = new Pose(randomPosition),
};
Simulation.RigidBodies.Add(body);
}
Shape sphereShape = new SphereShape(0.5f);
for (int i = 0; i < 10; i++)
{
Vector3F randomPosition = RandomHelper.Random.NextVector3F(-1, 1);
randomPosition.Length = 10;
RigidBody body = new RigidBody(sphereShape)
{
Pose = new Pose(randomPosition),
};
Simulation.RigidBodies.Add(body);
}
}
public ShapesSample(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);
// ----- Add a sphere.
Shape sphere = new SphereShape(0.5f);
Simulation.RigidBodies.Add(new RigidBody(sphere));
// ----- Add a box.
BoxShape box = new BoxShape(0.5f, 0.9f, 0.7f);
Simulation.RigidBodies.Add(new RigidBody(box));
// ----- Add a capsule.
CapsuleShape capsule = new CapsuleShape(0.4f, 1.2f);
Simulation.RigidBodies.Add(new RigidBody(capsule));
// ----- Add a cone.
ConeShape cone = new ConeShape(0.5f, 1f);
Simulation.RigidBodies.Add(new RigidBody(cone));
// ----- Add a cylinder.
CylinderShape cylinder = new CylinderShape(0.3f, 1f);
Simulation.RigidBodies.Add(new RigidBody(cylinder));
// ----- Add a convex hull of random points.
ConvexHullOfPoints convexHullOfPoints = new ConvexHullOfPoints();
for (int i = 0; i < 20; i++)
convexHullOfPoints.Points.Add(RandomHelper.Random.NextVector3F(-0.5f, 0.5f));
Simulation.RigidBodies.Add(new RigidBody(convexHullOfPoints));
// ----- Add a convex polyhedron.
// (A ConvexPolyhedron is similar to the ConvexHullOfPoints. The difference is that
// the points in a ConvexHullOfPoints can be changed at runtime. A ConvexPolyhedron
// cannot be changed at runtime, but it is faster.)
List<Vector3F> points = new List<Vector3F>();
for (int i = 0; i < 20; i++)
points.Add(RandomHelper.Random.NextVector3F(-0.7f, 0.7f));
ConvexPolyhedron convexPolyhedron = new ConvexPolyhedron(points);
Simulation.RigidBodies.Add(new RigidBody(convexPolyhedron));
// ----- Add a composite shape (a table that consists of 5 boxes).
CompositeShape composite = new CompositeShape();
composite.Children.Add(new GeometricObject(new BoxShape(0.1f, 0.8f, 0.1f), new Pose(new Vector3F(-0.75f, 0.4f, -0.5f))));
composite.Children.Add(new GeometricObject(new BoxShape(0.1f, 0.8f, 0.1f), new Pose(new Vector3F(0.75f, 0.4f, -0.5f))));
composite.Children.Add(new GeometricObject(new BoxShape(0.1f, 0.8f, 0.1f), new Pose(new Vector3F(-0.75f, 0.4f, 0.5f))));
composite.Children.Add(new GeometricObject(new BoxShape(0.1f, 0.8f, 0.1f), new Pose(new Vector3F(0.75f, 0.4f, 0.5f))));
composite.Children.Add(new GeometricObject(new BoxShape(1.8f, 0.1f, 1.1f), new Pose(new Vector3F(0, 0.8f, 0))));
Simulation.RigidBodies.Add(new RigidBody(composite));
// ----- Add a convex hull of multiple shapes.
ConvexHullOfShapes convexHullOfShapes = new ConvexHullOfShapes();
convexHullOfShapes.Children.Add(new GeometricObject(new CylinderShape(0.2f, 0.8f), new Pose(new Vector3F(-0.4f, 0, 0))));
convexHullOfShapes.Children.Add(new GeometricObject(new CylinderShape(0.2f, 0.8f), new Pose(new Vector3F(+0.4f, 0, 0))));
Simulation.RigidBodies.Add(new RigidBody(convexHullOfShapes));
// ----- Add the Minkowski sum of two shapes.
// (The Minkowski sum is a mathematical operation that combines two shapes.
// Here a circle is combined with a sphere. The result is a wheel.)
MinkowskiSumShape minkowskiSum = new MinkowskiSumShape();
minkowskiSum.ObjectA = new GeometricObject(new SphereShape(0.2f), Pose.Identity);
minkowskiSum.ObjectB = new GeometricObject(new CircleShape(0.5f), Pose.Identity);
Simulation.RigidBodies.Add(new RigidBody(minkowskiSum));
// Create another Minkowski sum. (Here a small sphere is added to a box to create a
// box with rounded corners.)
minkowskiSum = new MinkowskiSumShape();
minkowskiSum.ObjectA = new GeometricObject(new SphereShape(0.1f), Pose.Identity);
minkowskiSum.ObjectB = new GeometricObject(new BoxShape(0.2f, 0.5f, 0.8f), Pose.Identity);
Simulation.RigidBodies.Add(new RigidBody(minkowskiSum));
// ----- Add a triangle mesh.
// A triangle mesh could be loaded from a file or built from an XNA model.
// Here we first create a composite shape and convert the shape into a triangle
// mesh. (Any Shape in DigitalRune.Geometry can be converted to a triangle mesh.)
CompositeShape dumbbell = new CompositeShape();
dumbbell.Children.Add(new GeometricObject(new SphereShape(0.4f), new Pose(new Vector3F(0.6f, 0.0f, 0.0f))));
dumbbell.Children.Add(new GeometricObject(new SphereShape(0.4f), new Pose(new Vector3F(-0.6f, 0.0f, 0.0f))));
dumbbell.Children.Add(new GeometricObject(new CylinderShape(0.1f, 0.6f), new Pose(Matrix33F.CreateRotationZ(ConstantsF.PiOver2))));
TriangleMeshShape triangleMeshShape = new TriangleMeshShape(dumbbell.GetMesh(0.01f, 2));
// Optional: We can enable "contact welding". When this flag is enabled, the triangle shape
// precomputes additional internal information for the mesh. The collision detection will
// be able to compute better contacts (e.g. better normal vectors at triangle edges).
// Pro: Collision detection can compute better contact information.
// Con: Contact welding information needs a bit of memory. And the collision detection is
// a bit slower.
triangleMeshShape.EnableContactWelding = true;
// Optional: Assign a spatial partitioning scheme to the triangle mesh. (A spatial partition
// adds an additional memory overhead, but it improves collision detection speed tremendously!)
triangleMeshShape.Partition = new AabbTree<int>()
{
// The tree is automatically built using a mixed top-down/bottom-up approach. Bottom-up
// building is slower but produces better trees. If the tree building takes too long,
// we can lower the BottomUpBuildThreshold (default is 128).
BottomUpBuildThreshold = 0,
};
Simulation.RigidBodies.Add(new RigidBody(triangleMeshShape));
// ----- Set random positions/orientations.
// (Start with the second object. The first object is the ground plane which should
// not be changed.)
for (int i = 1; i < Simulation.RigidBodies.Count; i++)
{
RigidBody body = Simulation.RigidBodies[i];
Vector3F position = RandomHelper.Random.NextVector3F(-3, 3);
position.Y = 3; // Position the objects 3m above ground.
QuaternionF orientation = RandomHelper.Random.NextQuaternionF();
body.Pose = new Pose(position, orientation);
}
}
private static void GetMass(CylinderShape cylinder, Vector3F scale, float densityOrMass, bool isDensity, out float mass, out Matrix33F inertia)
{
scale = Vector3F.Absolute(scale);
float radiusX = cylinder.Radius * scale.X;
float heightY = cylinder.Height * scale.Y;
float radiusZ = cylinder.Radius * scale.Z;
mass = (isDensity) ? ConstantsF.Pi * radiusX * radiusZ * heightY * densityOrMass : densityOrMass;
inertia = Matrix33F.Zero;
inertia.M00 = 1.0f / 4.0f * mass * radiusZ * radiusZ + 1.0f / 12.0f * mass * heightY * heightY;
inertia.M11 = 1.0f / 4.0f * mass * radiusX * radiusX + 1.0f / 4.0f * mass * radiusZ * radiusZ;
inertia.M22 = 1.0f / 4.0f * mass * radiusX * radiusX + 1.0f / 12.0f * mass * heightY * heightY;
}
// Creates a lot of random objects.
private void CreateRandomObjects()
{
var random = new Random();
var isFirstHeightField = true;
int currentShape = 0;
int numberOfObjects = 0;
while (true)
{
numberOfObjects++;
if (numberOfObjects > ObjectsPerType)
{
currentShape++;
numberOfObjects = 0;
}
Shape shape;
switch (currentShape)
{
case 0:
// Box
shape = new BoxShape(ObjectSize, ObjectSize * 2, ObjectSize * 3);
break;
case 1:
// Capsule
shape = new CapsuleShape(0.3f * ObjectSize, 2 * ObjectSize);
break;
case 2:
// Cone
shape = new ConeShape(1 * ObjectSize, 2 * ObjectSize);
break;
case 3:
// Cylinder
shape = new CylinderShape(0.4f * ObjectSize, 2 * ObjectSize);
break;
case 4:
// Sphere
shape = new SphereShape(ObjectSize);
break;
case 5:
// Convex hull of several points.
ConvexHullOfPoints hull = new ConvexHullOfPoints();
hull.Points.Add(new Vector3F(-1 * ObjectSize, -2 * ObjectSize, -1 * ObjectSize));
hull.Points.Add(new Vector3F(2 * ObjectSize, -1 * ObjectSize, -0.5f * ObjectSize));
hull.Points.Add(new Vector3F(1 * ObjectSize, 2 * ObjectSize, 1 * ObjectSize));
hull.Points.Add(new Vector3F(-1 * ObjectSize, 2 * ObjectSize, 1 * ObjectSize));
hull.Points.Add(new Vector3F(-1 * ObjectSize, 0.7f * ObjectSize, -0.6f * ObjectSize));
shape = hull;
break;
case 6:
// A composite shape: two boxes that form a "T" shape.
var composite = new CompositeShape();
composite.Children.Add(
new GeometricObject(
new BoxShape(ObjectSize, 3 * ObjectSize, ObjectSize),
new Pose(new Vector3F(0, 0, 0))));
composite.Children.Add(
new GeometricObject(
new BoxShape(2 * ObjectSize, ObjectSize, ObjectSize),
new Pose(new Vector3F(0, 2 * ObjectSize, 0))));
shape = composite;
break;
case 7:
shape = new CircleShape(ObjectSize);
break;
case 8:
{
var compBvh = new CompositeShape();
compBvh.Children.Add(new GeometricObject(new BoxShape(0.5f, 1, 0.5f), new Pose(new Vector3F(0, 0.5f, 0), Matrix33F.Identity)));
compBvh.Children.Add(new GeometricObject(new BoxShape(0.8f, 0.5f, 0.5f), new Pose(new Vector3F(0.5f, 0.7f, 0), Matrix33F.CreateRotationZ(-MathHelper.ToRadians(15)))));
compBvh.Children.Add(new GeometricObject(new SphereShape(0.3f), new Pose(new Vector3F(0, 1.15f, 0), Matrix33F.Identity)));
compBvh.Children.Add(new GeometricObject(new CapsuleShape(0.2f, 1), new Pose(new Vector3F(0.6f, 1.15f, 0), Matrix33F.CreateRotationX(0.3f))));
compBvh.Partition = new AabbTree<int>();
shape = compBvh;
break;
}
case 9:
CompositeShape comp = new CompositeShape();
comp.Children.Add(new GeometricObject(new BoxShape(0.5f * ObjectSize, 1 * ObjectSize, 0.5f * ObjectSize), new Pose(new Vector3F(0, 0.5f * ObjectSize, 0), QuaternionF.Identity)));
comp.Children.Add(new GeometricObject(new BoxShape(0.8f * ObjectSize, 0.5f * ObjectSize, 0.5f * ObjectSize), new Pose(new Vector3F(0.3f * ObjectSize, 0.7f * ObjectSize, 0), QuaternionF.CreateRotationZ(-MathHelper.ToRadians(45)))));
comp.Children.Add(new GeometricObject(new SphereShape(0.3f * ObjectSize), new Pose(new Vector3F(0, 1.15f * ObjectSize, 0), QuaternionF.Identity)));
shape = comp;
break;
case 10:
shape = new ConvexHullOfPoints(new[]
{
new Vector3F(-1 * ObjectSize, -2 * ObjectSize, -1 * ObjectSize),
new Vector3F(2 * ObjectSize, -1 * ObjectSize, -0.5f * ObjectSize),
new Vector3F(1 * ObjectSize, 2 * ObjectSize, 1 * ObjectSize),
new Vector3F(-1 * ObjectSize, 2 * ObjectSize, 1 * ObjectSize),
new Vector3F(-1 * ObjectSize, 0.7f * ObjectSize, -0.6f * ObjectSize)
});
break;
case 11:
ConvexHullOfShapes shapeHull = new ConvexHullOfShapes();
shapeHull.Children.Add(new GeometricObject(new SphereShape(0.3f * ObjectSize), new Pose(new Vector3F(0, 2 * ObjectSize, 0), Matrix33F.Identity)));
shapeHull.Children.Add(new GeometricObject(new BoxShape(1 * ObjectSize, 2 * ObjectSize, 3 * ObjectSize), Pose.Identity));
shape = shapeHull;
break;
case 12:
shape = Shape.Empty;
break;
case 13:
var numberOfSamplesX = 10;
var numberOfSamplesZ = 10;
var samples = new float[numberOfSamplesX * numberOfSamplesZ];
for (int z = 0; z < numberOfSamplesZ; z++)
for (int x = 0; x < numberOfSamplesX; x++)
samples[z * numberOfSamplesX + x] = (float)(Math.Cos(z / 3f) * Math.Sin(x / 2f) * BoxSize / 6);
HeightField heightField = new HeightField(0, 0, 2 * BoxSize, 2 * BoxSize, samples, numberOfSamplesX, numberOfSamplesZ);
shape = heightField;
break;
//case 14:
//shape = new LineShape(new Vector3F(0.1f, 0.2f, 0.3f), new Vector3F(0.1f, 0.2f, -0.3f).Normalized);
//break;
case 15:
shape = new LineSegmentShape(
new Vector3F(0.1f, 0.2f, 0.3f), new Vector3F(0.1f, 0.2f, 0.3f) + 3 * ObjectSize * new Vector3F(0.1f, 0.2f, -0.3f));
break;
case 16:
shape = new MinkowskiDifferenceShape
{
ObjectA = new GeometricObject(new SphereShape(0.1f * ObjectSize)),
ObjectB = new GeometricObject(new BoxShape(1 * ObjectSize, 2 * ObjectSize, 3 * ObjectSize))
};
break;
case 17:
shape = new MinkowskiSumShape
{
ObjectA = new GeometricObject(new SphereShape(0.1f * ObjectSize)),
ObjectB = new GeometricObject(new BoxShape(1 * ObjectSize, 2 * ObjectSize, 3 * ObjectSize)),
};
break;
case 18:
shape = new OrthographicViewVolume(0, ObjectSize, 0, ObjectSize, ObjectSize / 2, ObjectSize * 2);
break;
case 19:
shape = new PerspectiveViewVolume(MathHelper.ToRadians(60f), 16f / 10, ObjectSize / 2, ObjectSize * 3);
break;
case 20:
shape = new PointShape(0.1f, 0.3f, 0.2f);
break;
case 21:
shape = new RayShape(new Vector3F(0.2f, 0, -0.12f), new Vector3F(1, 2, 3).Normalized, ObjectSize * 2);
break;
case 22:
shape = new RayShape(new Vector3F(0.2f, 0, -0.12f), new Vector3F(1, 2, 3).Normalized, ObjectSize * 2)
{
StopsAtFirstHit = true
};
break;
case 23:
shape = new RectangleShape(ObjectSize, ObjectSize * 2);
break;
case 24:
shape = new TransformedShape(
new GeometricObject(
new BoxShape(1 * ObjectSize, 2 * ObjectSize, 3 * ObjectSize),
new Pose(new Vector3F(0.1f, 1, -0.2f))));
break;
case 25:
shape = new TriangleShape(
new Vector3F(ObjectSize, 0, 0), new Vector3F(0, ObjectSize, 0), new Vector3F(ObjectSize, ObjectSize, ObjectSize));
break;
//case 26:
// {
// // Create a composite object from which we get the mesh.
// CompositeShape compBvh = new CompositeShape();
// compBvh.Children.Add(new GeometricObject(new BoxShape(0.5f, 1, 0.5f), new Pose(new Vector3F(0, 0.5f, 0), Matrix33F.Identity)));
// compBvh.Children.Add(
// new GeometricObject(
// new BoxShape(0.8f, 0.5f, 0.5f),
// new Pose(new Vector3F(0.5f, 0.7f, 0), Matrix33F.CreateRotationZ(-(float)MathHelper.ToRadians(15)))));
// compBvh.Children.Add(new GeometricObject(new SphereShape(0.3f), new Pose(new Vector3F(0, 1.15f, 0), Matrix33F.Identity)));
// compBvh.Children.Add(
// new GeometricObject(new CapsuleShape(0.2f, 1), new Pose(new Vector3F(0.6f, 1.15f, 0), Matrix33F.CreateRotationX(0.3f))));
// TriangleMeshShape meshBvhShape = new TriangleMeshShape { Mesh = compBvh.GetMesh(0.01f, 3) };
// meshBvhShape.Partition = new AabbTree<int>();
// shape = meshBvhShape;
// break;
// }
//case 27:
// {
// // Create a composite object from which we get the mesh.
// CompositeShape compBvh = new CompositeShape();
// compBvh.Children.Add(new GeometricObject(new BoxShape(0.5f, 1, 0.5f), new Pose(new Vector3F(0, 0.5f, 0), QuaternionF.Identity)));
// compBvh.Children.Add(
// new GeometricObject(
// new BoxShape(0.8f, 0.5f, 0.5f),
// new Pose(new Vector3F(0.5f, 0.7f, 0), QuaternionF.CreateRotationZ(-(float)MathHelper.ToRadians(15)))));
// compBvh.Children.Add(new GeometricObject(new SphereShape(0.3f), new Pose(new Vector3F(0, 1.15f, 0), QuaternionF.Identity)));
// compBvh.Children.Add(
// new GeometricObject(new CapsuleShape(0.2f, 1), new Pose(new Vector3F(0.6f, 1.15f, 0), QuaternionF.CreateRotationX(0.3f))));
// TriangleMeshShape meshBvhShape = new TriangleMeshShape { Mesh = compBvh.GetMesh(0.01f, 3) };
// meshBvhShape.Partition = new AabbTree<int>();
// shape = meshBvhShape;
// break;
// }
case 28:
shape = new ConvexPolyhedron(new[]
{
new Vector3F(-1 * ObjectSize, -2 * ObjectSize, -1 * ObjectSize),
new Vector3F(2 * ObjectSize, -1 * ObjectSize, -0.5f * ObjectSize),
new Vector3F(1 * ObjectSize, 2 * ObjectSize, 1 * ObjectSize),
new Vector3F(-1 * ObjectSize, 2 * ObjectSize, 1 * ObjectSize),
new Vector3F(-1 * ObjectSize, 0.7f * ObjectSize, -0.6f * ObjectSize)
});
break;
case 29:
return;
default:
currentShape++;
continue;
}
// Create an object with the random shape, pose, color and velocity.
Pose randomPose = new Pose(
random.NextVector3F(-BoxSize + ObjectSize * 2, BoxSize - ObjectSize * 2),
random.NextQuaternionF());
var newObject = new MovingGeometricObject
{
Pose = randomPose,
Shape = shape,
LinearVelocity = random.NextQuaternionF().Rotate(new Vector3F(MaxLinearVelocity, 0, 0)),
AngularVelocity = random.NextQuaternionF().Rotate(Vector3F.Forward)
* RandomHelper.Random.NextFloat(0, MaxAngularVelocity),
};
if (RandomHelper.Random.NextBool())
newObject.LinearVelocity = Vector3F.Zero;
if (RandomHelper.Random.NextBool())
newObject.AngularVelocity = Vector3F.Zero;
if (shape is LineShape || shape is HeightField)
{
// Do not move lines or the height field.
newObject.LinearVelocity = Vector3F.Zero;
newObject.AngularVelocity = Vector3F.Zero;
}
// Create only 1 heightField!
if (shape is HeightField)
{
if (isFirstHeightField)
{
isFirstHeightField = true;
newObject.Pose = new Pose(new Vector3F(-BoxSize, -BoxSize, -BoxSize));
}
else
{
currentShape++;
numberOfObjects = 0;
continue;
}
}
// Add collision object to collision domain.
_domain.CollisionObjects.Add(new CollisionObject(newObject));
//co.Type = CollisionObjectType.Trigger;
//co.Name = "Object" + shape.GetType().Name + "_" + i;
}
}
public void GeneralShape()
{
var s = new CylinderShape(1, 3);
float m0;
Vector3F com0;
Matrix33F i0;
MassHelper.GetMass(s, new Vector3F(1, -2, -3), 0.7f, true, 0.001f, 4, out m0, out com0, out i0);
var m = s.GetMesh(0.001f, 10);
var s2 = new TriangleMeshShape(m);
float m1;
Vector3F com1;
Matrix33F i1;
MassHelper.GetMass(s2, new Vector3F(1, -2, -3), 0.7f, true, 0.001f, 4, out m1, out com1, out i1);
const float e = 0.01f;
Assert.IsTrue(Numeric.AreEqual(m0, m1, e * (1 + m0)));
Assert.IsTrue(Vector3F.AreNumericallyEqual(com0, com1, e * (1 + com0.Length)));
Assert.IsTrue(Matrix33F.AreNumericallyEqual(i0, i1, e * (1 + i0.Trace)));
// Try with target mass.
float m2;
Vector3F com2;
Matrix33F i2;
MassHelper.GetMass(s2, new Vector3F(1, -2, -3), 23, false, 0.001f, 4, out m2, out com2, out i2);
Assert.IsTrue(Numeric.AreEqual(23, m2, e * (1 + m0)));
Assert.IsTrue(Vector3F.AreNumericallyEqual(com0, com2, e * (1 + com0.Length)));
Assert.IsTrue(Matrix33F.AreNumericallyEqual(i0 * 23 / m0, i2, e * (1 + i0.Trace)));
}
public BuoyancySample(Microsoft.Xna.Framework.Game game)
: base(game)
{
// Add basic force effects.
Simulation.ForceEffects.Add(new Gravity());
Simulation.ForceEffects.Add(new Damping());
// ----- Buoyancy Force Effect
// Buoyancy is a force effect that lets bodies swim in water. The water area is
// defined by two properties:
// - Buoyancy.AreaOfEffect defines which objects are affected.
// - Buoyancy.Surface defines the water level within this area.
// The area of effect can be defined in different ways. In this sample we will use
// a geometric object ("trigger volume").
// First, define the shape of the water area. We will create simple pool.
Shape poolShape = new BoxShape(16, 10, 16);
Vector3F poolCenter = new Vector3F(0, -5, 0);
// Then create a geometric object for the water area. (A GeometricObject is required
// to position the shape in the world. A GeometricObject stores shape, scale, position,
// orientation, ...)
GeometricObject waterGeometry = new GeometricObject(poolShape, new Pose(poolCenter));
// Then create a collision object for the geometric object. (A CollisionObject required
// because the geometry should be used for collision detection with other objects.)
_waterCollisionObject = new CollisionObject(waterGeometry)
{
// Assign the object to a different collision group:
// The Grab component (see Grab.cs) uses a ray to perform hit tests. We don't want the ray
// to collide with the water. Therefore, we need to assign the water collision object to a
// different collision group. The general geometry is in collision group 0. The rays are in
// collision group 2. Add the water to collision group 1. Collision between 0 and 2 are
// enabled. Collision between 1 and 2 need to be disabled - this collision filter was set
// in PhysicsGame.cs.
CollisionGroup = 1,
// Set the type to "Trigger". This improves the performance because the collision
// detection does not need to compute detailed contact information. The collision
// detection only returns whether an objects has contact with the water.
Type = CollisionObjectType.Trigger,
};
// The collision object needs to be added into the collision domain of the simulation.
Simulation.CollisionDomain.CollisionObjects.Add(_waterCollisionObject);
// Now we can add the buoyancy effect.
Buoyancy buoyancy = new Buoyancy
{
AreaOfEffect = new GeometricAreaOfEffect(_waterCollisionObject),
Surface = new Plane(Vector3F.Up, 0),
Density = 1000f, // The density of water (1000 kg/m³).
AngularDrag = 0.4f,
LinearDrag = 4f,
// Optional: Let the objects drift in the water by setting a flow velocity.
//Velocity = new Vector3F(-0.5f, 0, 0.5f),
};
Simulation.ForceEffects.Add(buoyancy);
// Add static area around the pool.
RigidBody bottom = new RigidBody(new BoxShape(36, 2, 36))
{
MotionType = MotionType.Static,
Pose = new Pose(new Vector3F(0, -11, 0)),
};
Simulation.RigidBodies.Add(bottom);
RigidBody left = new RigidBody(new BoxShape(10, 10, 36))
{
MotionType = MotionType.Static,
Pose = new Pose(new Vector3F(-13, -5, 0)),
};
Simulation.RigidBodies.Add(left);
RigidBody right = new RigidBody(new BoxShape(10, 10, 36))
{
MotionType = MotionType.Static,
Pose = new Pose(new Vector3F(13, -5, 0)),
};
Simulation.RigidBodies.Add(right);
RigidBody front = new RigidBody(new BoxShape(16, 10, 10))
{
MotionType = MotionType.Static,
Pose = new Pose(new Vector3F(0, -5, 13)),
};
Simulation.RigidBodies.Add(front);
RigidBody back = new RigidBody(new BoxShape(16, 10, 10))
{
MotionType = MotionType.Static,
Pose = new Pose(new Vector3F(0, -5, -13)),
};
Simulation.RigidBodies.Add(back);
// ----- Add some random objects to test the effect.
// Note: Objects swim if their density is less than the density of water. They sink
// if the density is greater than the density of water.
// We can define the density of objects by explicitly setting the mass.
// Add a swimming board.
BoxShape raftShape = new BoxShape(4, 0.3f, 4);
MassFrame raftMass = MassFrame.FromShapeAndDensity(raftShape, Vector3F.One, 700, 0.01f, 3);
RigidBody raft = new RigidBody(raftShape, raftMass, null)
{
Pose = new Pose(new Vector3F(0, 4, 0)),
};
Simulation.RigidBodies.Add(raft);
// Add some boxes on top of the swimming board.
BoxShape boxShape = new BoxShape(1, 1, 1);
MassFrame boxMass = MassFrame.FromShapeAndDensity(boxShape, Vector3F.One, 700, 0.01f, 3);
for (int i = 0; i < 5; i++)
{
RigidBody box = new RigidBody(boxShape, boxMass, null)
{
Pose = new Pose(new Vector3F(0, 5 + i * 1.1f, 0)),
};
Simulation.RigidBodies.Add(box);
}
// Add some "heavy stones" represented as spheres.
SphereShape stoneShape = new SphereShape(0.5f);
MassFrame stoneMass = MassFrame.FromShapeAndDensity(stoneShape, Vector3F.One, 2500, 0.01f, 3);
for (int i = 0; i < 10; i++)
{
Vector3F position = RandomHelper.Random.NextVector3F(-9, 9);
position.Y = 5;
RigidBody stone = new RigidBody(stoneShape, stoneMass, null)
{
Pose = new Pose(position),
};
Simulation.RigidBodies.Add(stone);
}
// Add some very light objects.
CylinderShape cylinderShape = new CylinderShape(0.3f, 1);
MassFrame cylinderMass = MassFrame.FromShapeAndDensity(cylinderShape, Vector3F.One, 500, 0.01f, 3);
for (int i = 0; i < 10; i++)
{
Vector3F position = RandomHelper.Random.NextVector3F(-9, 9);
position.Y = 5;
QuaternionF orientation = RandomHelper.Random.NextQuaternionF();
RigidBody cylinder = new RigidBody(cylinderShape, cylinderMass, null)
{
Pose = new Pose(position, orientation),
};
Simulation.RigidBodies.Add(cylinder);
}
}
public void CylinderMass()
{
var s = new CylinderShape(1, 3);
float m0;
Vector3F com0;
Matrix33F i0;
MassHelper.GetMass(s, new Vector3F(1, -2, -3), 1, true, 0.001f, 10, out m0, out com0, out i0);
var m = s.GetMesh(0.001f, 10);
m.Transform(Matrix44F.CreateScale(1, -2, -3));
float m1;
Vector3F com1;
Matrix33F i1;
MassHelper.GetMass(m, out m1, out com1, out i1);
const float e = 0.01f;
Assert.IsTrue(Numeric.AreEqual(m0, m1, e * (1 + m0)));
Assert.IsTrue(Vector3F.AreNumericallyEqual(com0, com1, e * (1 + com0.Length)));
Assert.IsTrue(Matrix33F.AreNumericallyEqual(i0, i1, e * (1 + i0.Trace)));
// Try other density.
float m2;
Vector3F com2;
Matrix33F i2;
MassHelper.GetMass(s, new Vector3F(1, -2, -3), 0.7f, true, 0.001f, 10, out m2, out com2, out i2);
Assert.IsTrue(Numeric.AreEqual(m0 * 0.7f, m2, e * (1 + m0)));
Assert.IsTrue(Vector3F.AreNumericallyEqual(com0, com2, e * (1 + com0.Length)));
Assert.IsTrue(Matrix33F.AreNumericallyEqual(i0 * 0.7f, i2, e * (1 + i0.Trace)));
// Try with target mass.
float m3;
Vector3F com3;
Matrix33F i3;
MassHelper.GetMass(s, new Vector3F(1, -2, -3), 23, false, 0.001f, 10, out m3, out com3, out i3);
Assert.IsTrue(Numeric.AreEqual(23, m3, e * (1 + m0)));
Assert.IsTrue(Vector3F.AreNumericallyEqual(com0, com3, e * (1 + com0.Length)));
Assert.IsTrue(Matrix33F.AreNumericallyEqual(i0 * 23 / m0, i3, e * (1 + i0.Trace)));
}
public void TriangleMeshShapeTest()
{
var s = new CylinderShape(1, 2);
var v0 = s.GetVolume(0.001f, 10);
var m = s.GetMesh(0.001f, 10);
var s1 = new TriangleMeshShape(m);
var v1 = m.GetVolume();
Assert.IsTrue(Numeric.AreEqual(v0, v1, 0.01f * (1 + v0))); // 1% error is allowed.
}
public void ScaledConvexShape()
{
var s = new CylinderShape(1, 2);
var v0 = s.GetVolume(0.001f, 10);
var s1 = new ScaledConvexShape(new CylinderShape(10, 10), new Vector3F(0.1f, 0.2f, 0.1f));
var v1 = s1.GetVolume(0.0001f, 10);
Assert.IsTrue(Numeric.AreEqual(v0, v1, 0.01f * (1 + v0))); // 1% error is allowed.
}
// Creates a lot of random objects.
private void CreateRandomObjects()
{
var random = new Random(12345);
for (int i = 0; i < NumberOfObjects; i++)
{
// Randomly choose a shape.
Shape randomShape;
switch (random.Next(0, 7))
{
case 0:
// Box
randomShape = new BoxShape(ObjectSize, ObjectSize * 2, ObjectSize * 3);
break;
case 1:
// Capsule
randomShape = new CapsuleShape(0.3f * ObjectSize, 2 * ObjectSize);
break;
case 2:
// Cone
randomShape = new ConeShape(1 * ObjectSize, 2 * ObjectSize);
break;
case 3:
// Cylinder
randomShape = new CylinderShape(0.4f * ObjectSize, 2 * ObjectSize);
break;
case 4:
// Sphere
randomShape = new SphereShape(ObjectSize);
break;
case 5:
// Convex hull of several points.
ConvexHullOfPoints hull = new ConvexHullOfPoints();
hull.Points.Add(new Vector3F(-1 * ObjectSize, -2 * ObjectSize, -1 * ObjectSize));
hull.Points.Add(new Vector3F(2 * ObjectSize, -1 * ObjectSize, -0.5f * ObjectSize));
hull.Points.Add(new Vector3F(1 * ObjectSize, 2 * ObjectSize, 1 * ObjectSize));
hull.Points.Add(new Vector3F(-1 * ObjectSize, 2 * ObjectSize, 1 * ObjectSize));
hull.Points.Add(new Vector3F(-1 * ObjectSize, 0.7f * ObjectSize, -0.6f * ObjectSize));
randomShape = hull;
break;
case 6:
// A composite shape: two boxes that form a "T" shape.
var composite = new CompositeShape();
composite.Children.Add(
new GeometricObject(
new BoxShape(ObjectSize, 3 * ObjectSize, ObjectSize),
new Pose(new Vector3F(0, 0, 0))));
composite.Children.Add(
new GeometricObject(
new BoxShape(2 * ObjectSize, ObjectSize, ObjectSize),
new Pose(new Vector3F(0, 2 * ObjectSize, 0))));
randomShape = composite;
break;
default:
#if WINDOWS
Trace.Fail("Ups, we shouldn't land here :-(");
#endif
randomShape = new SphereShape();
break;
}
// Create an object with the random shape, pose, color and velocity.
Pose randomPose = new Pose(
random.NextVector3F(-BoxSize + ObjectSize * 2, BoxSize - ObjectSize * 2),
random.NextQuaternionF());
var newObject = new MovingGeometricObject
{
Pose = randomPose,
Shape = randomShape,
LinearVelocity = random.NextQuaternionF().Rotate(new Vector3F(MaxLinearVelocity, 0, 0)),
AngularVelocity = random.NextQuaternionF().Rotate(Vector3F.Forward)
* RandomHelper.Random.NextFloat(0, MaxAngularVelocity),
};
// Add collision object to collision domain.
_domain.CollisionObjects.Add(new CollisionObject(newObject));
// We will collect a few statistics for debugging.
Profiler.SetFormat("NumObjects", 1, "The total number of objects.");
Profiler.SetFormat("NumObjectPairs", 1, "The number of objects pairs, which have to be checked.");
Profiler.SetFormat("BroadPhasePairs", 1, "The number of overlaps reported by the broad phase.");
Profiler.SetFormat("ContactSetCount", 1, "The number of actual collisions.");
}
}
public ConstraintCarSample(Microsoft.Xna.Framework.Game game)
: base(game)
{
// Add basic force effects.
Simulation.ForceEffects.Add(new Gravity());
Simulation.ForceEffects.Add(new Damping());
// Create a material with high friction - this will be used for the ground and the wheels
// to give the wheels some traction.
UniformMaterial roughMaterial = new UniformMaterial
{
DynamicFriction = 1,
StaticFriction = 1,
};
// Add a ground plane.
RigidBody groundPlane = new RigidBody(new PlaneShape(Vector3F.UnitY, 0), null, roughMaterial)
{
MotionType = MotionType.Static,
};
Simulation.RigidBodies.Add(groundPlane);
// Now, we build a car out of one box for the chassis and 4 cylindric wheels.
// Front wheels are fixed with Hinge2Joints and motorized with AngularVelocityMotors.
// Back wheels are fixed with HingeJoints and not motorized. - This creates a sloppy
// car configuration. Please note that cars for racing games are not normally built with
// simple constraints - nevertheless, it is funny to do and play with it.
// Check out the "Vehicle Sample" (not included in this project)! The "Vehicle Sample"
// provides a robust ray-car implementation.)
// ----- Chassis
BoxShape chassisShape = new BoxShape(1.7f, 1, 4f);
MassFrame chassisMass = MassFrame.FromShapeAndDensity(chassisShape, Vector3F.One, 200, 0.01f, 3);
// Here is a trick: The car topples over very easily. By lowering the center of mass we
// make it more stable.
chassisMass.Pose = new Pose(new Vector3F(0, -1, 0));
RigidBody chassis = new RigidBody(chassisShape, chassisMass, null)
{
Pose = new Pose(new Vector3F(0, 1, 0)),
};
Simulation.RigidBodies.Add(chassis);
// ------ Wheels
CylinderShape cylinderShape = new CylinderShape(0.4f, 0.3f);
MassFrame wheelMass = MassFrame.FromShapeAndDensity(cylinderShape, Vector3F.One, 500, 0.01f, 3);
RigidBody wheelFrontLeft = new RigidBody(cylinderShape, wheelMass, roughMaterial)
{
Pose = new Pose(new Vector3F(0, 1, 0), Matrix33F.CreateRotationZ(ConstantsF.PiOver2)),
};
Simulation.RigidBodies.Add(wheelFrontLeft);
RigidBody wheelFrontRight = new RigidBody(cylinderShape, wheelMass, roughMaterial)
{
Pose = new Pose(new Vector3F(0, 1, 0), Matrix33F.CreateRotationZ(ConstantsF.PiOver2)),
};
Simulation.RigidBodies.Add(wheelFrontRight);
RigidBody wheelBackLeft = new RigidBody(cylinderShape, wheelMass, roughMaterial)
{
Pose = new Pose(new Vector3F(0, 1, 0), Matrix33F.CreateRotationZ(ConstantsF.PiOver2)),
};
Simulation.RigidBodies.Add(wheelBackLeft);
RigidBody wheelBackRight = new RigidBody(cylinderShape, wheelMass, roughMaterial)
{
Pose = new Pose(new Vector3F(0, 1, 0), Matrix33F.CreateRotationZ(ConstantsF.PiOver2)),
};
Simulation.RigidBodies.Add(wheelBackRight);
// ----- Hinge2Joints for the front wheels.
// A Hinge2Joint allows a limited rotation on the first constraint axis - the steering
// axis. The second constraint axis is locked and the third constraint axis is the
// rotation axis of the wheels.
_frontLeftHinge = new Hinge2Joint
{
BodyA = chassis,
// --> To define the constraint anchor orientation for the chassis:
// The columns are the axes. We set the local y axis in the first column. This is
// steering axis. In the last column we set the -x axis. This is the wheel rotation axis.
// In the middle column is a vector that is normal to the first and last axis.
// (All three columns are orthonormal and form a valid rotation matrix.)
AnchorPoseALocal = new Pose(new Vector3F(-0.9f, -0.4f, -1.4f),
new Matrix33F(0, 0, -1,
1, 0, 0,
0, -1, 0)),
BodyB = wheelFrontLeft,
// --> To define the constraint anchor orientation for the chassis:
// The columns are the axes. We set the local x axis in the first column. This is
// steering axis. In the last column we set the y axis. This is the wheel rotation axis.
// (In local space of a cylinder the cylinder axis is the +y axis.)
// In the middle column is a vector that is normal to the first and last axis.
// (All three columns are orthonormal and form a valid rotation matrix.)
AnchorPoseBLocal = new Pose(new Matrix33F(1, 0, 0,
0, 0, 1,
0, -1, 0)),
CollisionEnabled = false,
Minimum = new Vector2F(-0.7f, float.NegativeInfinity),
Maximum = new Vector2F(0.7f, float.PositiveInfinity),
};
Simulation.Constraints.Add(_frontLeftHinge);
_frontRightHinge = new Hinge2Joint
{
BodyA = chassis,
BodyB = wheelFrontRight,
AnchorPoseALocal = new Pose(new Vector3F(0.9f, -0.4f, -1.4f),
new Matrix33F(0, 0, -1,
1, 0, 0,
0, -1, 0)),
AnchorPoseBLocal = new Pose(new Matrix33F(1, 0, 0,
0, 0, 1,
0, -1, 0)),
CollisionEnabled = false,
Minimum = new Vector2F(-0.7f, float.NegativeInfinity),
Maximum = new Vector2F(0.7f, float.PositiveInfinity),
};
Simulation.Constraints.Add(_frontRightHinge);
// ----- HingeJoints for the back wheels.
// Hinges allow free rotation on the first constraint axis.
HingeJoint backLeftHinge = new HingeJoint
{
BodyA = chassis,
AnchorPoseALocal = new Pose(new Vector3F(-0.9f, -0.4f, 1.4f)),
BodyB = wheelBackLeft,
// --> To define the constraint anchor orientation:
// The columns are the axes. We set the local y axis in the first column. This is
// cylinder axis and should be the hinge axis. In the other two columns we set two
// orthonormal vectors.
// (All three columns are orthonormal and form a valid rotation matrix.)
AnchorPoseBLocal = new Pose(new Matrix33F(0, 0, 1,
1, 0, 0,
0, 1, 0)),
CollisionEnabled = false,
};
Simulation.Constraints.Add(backLeftHinge);
HingeJoint backRightHinge = new HingeJoint
{
BodyA = chassis,
AnchorPoseALocal = new Pose(new Vector3F(0.9f, -0.4f, 1.4f)),
BodyB = wheelBackRight,
AnchorPoseBLocal = new Pose(new Matrix33F(0, 0, 1,
1, 0, 0,
0, 1, 0)),
CollisionEnabled = false,
};
Simulation.Constraints.Add(backRightHinge);
// ----- Motors for the front wheels.
// (Motor axes and target velocities are set in Update() below.)
_frontLeftMotor = new AngularVelocityMotor
{
BodyA = chassis,
BodyB = wheelFrontLeft,
CollisionEnabled = false,
// We use "single axis mode", which means the motor drives only on axis and does not
// block motion orthogonal to this axis. - Rotation about the orthogonal axes is already
// controlled by the Hinge2Joint.
UseSingleAxisMode = true,
// The motor has only limited power:
MaxForce = 50000,
};
Simulation.Constraints.Add(_frontLeftMotor);
_frontRightMotor = new AngularVelocityMotor
{
BodyA = chassis,
BodyB = wheelFrontRight,
CollisionEnabled = false,
UseSingleAxisMode = true,
MaxForce = 50000,
};
Simulation.Constraints.Add(_frontRightMotor);
// ----- Drop a few boxes to create obstacles.
BoxShape boxShape = new BoxShape(1, 1, 1);
MassFrame boxMass = MassFrame.FromShapeAndDensity(boxShape, Vector3F.One, 100, 0.01f, 3);
for (int i = 0; i < 20; i++)
{
Vector3F position = RandomHelper.Random.NextVector3F(-20, 20);
position.Y = 5;
QuaternionF orientation = RandomHelper.Random.NextQuaternionF();
RigidBody body = new RigidBody(boxShape, boxMass, null)
{
Pose = new Pose(position, orientation),
};
Simulation.RigidBodies.Add(body);
}
}