// Barycentric coordinates
// -----------------------
// We can find a set of multipliers {m1, m2, m3) of triangle
// vertices {V1, V2, V3} such that any point P in the plane
// can be represented as m1V1 + m2V2 + m3V3. With the addition
// of normalization constraint m1 + m2 + m3 = 1, we can write
// this as:
//
// Px | v1x v2x v3x | m1
// Py = | v1y v2y v3y | * m2
// 1 | 1 1 1 | m3
//
// The inverse of the |V| matrix depicted above converts real
// points into their multipliers. The conversion matricies are
// assigned to the tri[] entries here.
//
static void BarycentricMatrices(
vector<triangle> &tri,
const vector<vertex> &ctl,
FILE* flog )
{
int ntri = tri.size();
for( int k = 0; k < ntri; ++k ) {
triangle& T = tri[k];
vertex v0 = ctl[T.v[0]],
v1 = ctl[T.v[1]],
v2 = ctl[T.v[2]];
double a[3][3];
fprintf( flog,
"Tri: (%d %d) (%d %d) (%d %d).\n",
v0.x, v0.y, v1.x, v1.y, v2.x, v2.y );
a[0][0] = v0.x; a[0][1] = v1.x; a[0][2] = v2.x;
a[1][0] = v0.y; a[1][1] = v1.y; a[1][2] = v2.y;
a[2][0] = 1.0; a[2][1] = 1.0; a[2][2] = 1.0;
Invert3x3Matrix( T.a, a );
}
}
void RigidBody_GeneralTensor::SetInertiaTensor(double inertiaTensorAtRest[9], int updateAngularVelocity)
{
memcpy(this->inertiaTensorAtRest, inertiaTensorAtRest, sizeof(double) * 9);
// compute inverse inertia tensor at rest
Invert3x3Matrix(this->inertiaTensorAtRest, inverseInertiaTensorAtRest);
inverseInertiaTensorAtRestX = inverseInertiaTensorAtRest[0];
inverseInertiaTensorAtRestY = inverseInertiaTensorAtRest[4];
inverseInertiaTensorAtRestZ = inverseInertiaTensorAtRest[8];
// change the angular velocity accordingly
if (updateAngularVelocity)
ComputeAngularVelocity();
}
