public bool Remove(Shape shape)
{
if (shapes.Count == 1) throw new Exception("There must be at least one shape.");
bool result = shapes.Remove(shape);
UpdateShape();
return result;
}
public void AddShape(Shape shape)
{
if (shape is Multishape) throw new Exception("Multishapes not supported by MinkowskiSumShape.");
shapes.Add(shape);
this.UpdateShape();
}
/// <summary>
/// Creates a new instance of the TransformedShape struct.
/// </summary>
/// <param name="shape">The shape.</param>
/// <param name="orientation">The orientation this shape should have.</param>
/// <param name="position">The position this shape should have.</param>
public TransformedShape(Shape shape, JMatrix orientation, JVector position)
{
this.position = position;
this.orientation = orientation;
JMatrix.Transpose(ref orientation, out invOrientation);
this.shape = shape;
this.boundingBox = new JBBox();
UpdateBoundingBox();
}
public MassPoint(Shape shape, SoftBody owner, Material material)
: base(shape, material, true)
{
this.SoftBody = owner;
}
public static float CalculateMassInertia(Shape shape, out JVector centerOfMass,
out JMatrix inertia)
{
float mass = 0.0f;
centerOfMass = JVector.Zero; inertia = JMatrix.Zero;
if (shape is Multishape) throw new ArgumentException("Can't calculate inertia of multishapes.", "shape");
// build a triangle hull around the shape
List<JVector> hullTriangles = new List<JVector>();
shape.MakeHull(ref hullTriangles, 3);
// create inertia of tetrahedron with vertices at
// (0,0,0) (1,0,0) (0,1,0) (0,0,1)
float a = 1.0f / 60.0f, b = 1.0f / 120.0f;
JMatrix C = new JMatrix(a, b, b, b, a, b, b, b, a);
for (int i = 0; i < hullTriangles.Count; i += 3)
{
JVector column0 = hullTriangles[i + 0];
JVector column1 = hullTriangles[i + 1];
JVector column2 = hullTriangles[i + 2];
JMatrix A = new JMatrix(column0.X, column1.X, column2.X,
column0.Y, column1.Y, column2.Y,
column0.Z, column1.Z, column2.Z);
float detA = A.Determinant();
// now transform this canonical tetrahedron to the target tetrahedron
// inertia by a linear transformation A
JMatrix tetrahedronInertia = JMatrix.Multiply(A * C * JMatrix.Transpose(A), detA);
JVector tetrahedronCOM = (1.0f / 4.0f) * (hullTriangles[i + 0] + hullTriangles[i + 1] + hullTriangles[i + 2]);
float tetrahedronMass = (1.0f / 6.0f) * detA;
inertia += tetrahedronInertia;
centerOfMass += tetrahedronMass * tetrahedronCOM;
mass += tetrahedronMass;
}
inertia = JMatrix.Multiply(JMatrix.Identity, inertia.Trace()) - inertia;
centerOfMass = centerOfMass * (1.0f / mass);
float x = centerOfMass.X;
float y = centerOfMass.Y;
float z = centerOfMass.Z;
// now translate the inertia by the center of mass
JMatrix t = new JMatrix(
-mass * (y * y + z * z), mass * x * y, mass * x * z,
mass * y * x, -mass * (z * z + x * x), mass * y * z,
mass * z * x, mass * z * y, -mass * (x * x + y * y));
JMatrix.Add(ref inertia, ref t, out inertia);
return mass;
}
