// Compute the OBB for a set of points relative to a transform matrix and see if it is smaller than the current best value. If
// so, return it.
static void
computeOBB(TheaArray<Vector3> const & points, CoordinateFrame3 const & cframe, OBB & current_best_result, bool overwrite)
{
if (points.empty())
return;
Vector3 lo, hi;
lo = hi = cframe.pointToObjectSpace(points[0]);
Vector3 p;
for (array_size_t i = 1; i < points.size(); ++i)
{
p = cframe.pointToObjectSpace(points[i]);
lo = lo.min(p);
hi = hi.max(p);
}
Vector3 e = hi - lo;
double volume = e.x() * e.y() * e.z();
if (overwrite || volume < current_best_result.volume)
{
Vector3 c = 0.5f * (lo + hi);
Vector3 he = 0.5f * e;
current_best_result = OBB(c - he, c + he, cframe, volume);
}
}
// A rather hacky way of forming a joint descriptor, suitable only for exact matches like we want here
void
accumGroupFeatures(MeshGroup const & mg, TheaArray<double> & features)
{
for (MeshGroup::MeshConstIterator mi = mg.meshesBegin(); mi != mg.meshesEnd(); ++mi)
{
TheaArray<double> const & mf = (*mi)->getFeatures();
if (features.empty())
features.resize(mf.size());
alwaysAssertM(mf.size() == features.size(), "Feature vectors have different sizes");
for (array_size_t j = 0; j < features.size(); ++j)
features[j] += mf[j];
}
for (MeshGroup::GroupConstIterator ci = mg.childrenBegin(); ci != mg.childrenEnd(); ++ci)
accumGroupFeatures(**ci, features);
}
static void
computeBestFitOBB(TheaArray<Vector3> const & points, Box3 & result, bool has_up, Vector3 const & up)
{
if (points.empty())
{
result = Box3();
return;
}
else if (points.size() == 1)
{
result = Box3(AxisAlignedBox3(points[0]));
return;
}
Vector3 centroid;
CoordinateFrame3 cframe;
if (has_up)
{
centroid = CentroidN<Vector3, 3>::compute(points.begin(), points.end());
Vector3 u, v;
up.createOrthonormalBasis(u, v);
cframe = CoordinateFrame3::_fromAffine(AffineTransform3(basisMatrix(u, v, up), centroid));
}
else
{
Plane3 plane;
LinearLeastSquares3<Vector3>::fitPlane(points.begin(), points.end(), plane, ¢roid);
planeToCFrame(plane, centroid, cframe);
}
OBB best_obb;
computeOBB(points, cframe, best_obb, true);
Matrix3 rot = Matrix3::rotationAxisAngle((has_up ? up : Vector3::unitY()), Math::degreesToRadians(10));
for (int a = 10; a < 180; a += 10)
{
cframe._setRotation(cframe.getRotation() * rot);
computeOBB(points, cframe, best_obb, false);
}
result = Box3(AxisAlignedBox3(best_obb.lo, best_obb.hi), best_obb.cframe);
}
