MObject readNurbs(double iFrame, Alembic::AbcGeom::INuPatch & iNode,
MObject & iObject)
{
MStatus status;
MObject obj;
Alembic::AbcGeom::INuPatchSchema schema = iNode.getSchema();
// no interpolation for now
Alembic::AbcCoreAbstract::index_t index, ceilIndex;
getWeightAndIndex(iFrame, schema.getTimeSampling(),
schema.getNumSamples(), index, ceilIndex);
Alembic::AbcGeom::INuPatchSchema::Sample samp;
schema.get(samp, Alembic::Abc::ISampleSelector(index));
Alembic::Abc::P3fArraySamplePtr pos = samp.getPositions();
Alembic::Abc::FloatArraySamplePtr weights = samp.getPositionWeights();
MString surfaceName(iNode.getName().c_str());
unsigned int degreeU = samp.getUOrder() - 1;
unsigned int degreeV = samp.getVOrder() - 1;
unsigned int numCVInU = samp.getNumU();
unsigned int numCVInV = samp.getNumV();
// cv points
unsigned int numCV = numCVInU*numCVInV;
unsigned int curPos = 0;
MPointArray controlVertices;
controlVertices.setLength(numCV);
for (unsigned int v = 0; v < numCVInV; ++v)
{
for (unsigned int u = 0; u < numCVInU; ++u, ++curPos)
{
unsigned int mayaIndex = u * numCVInV + (numCVInV - v - 1);
MPoint pt((*pos)[curPos].x, (*pos)[curPos].y, (*pos)[curPos].z);
if (weights)
{
pt.w = (*weights)[curPos];
}
// go from u,v order to reversed v, u order
controlVertices.set(pt, mayaIndex);
}
}
// Nurbs form
// Alemblic file does not record the form of nurb surface, we get the form
// by checking the CV data. If the first degree number CV overlap the last
// degree number CV, then the form is kPeriodic. If only the first CV overlaps
// the last CV, then the form is kClosed.
MFnNurbsSurface::Form formU = MFnNurbsSurface::kPeriodic;
MFnNurbsSurface::Form formV = MFnNurbsSurface::kPeriodic;
// Check all curves
bool notOpen = true;
for (unsigned int v = 0; notOpen && v < numCVInV; v++) {
for (unsigned int u = 0; u < degreeU; u++) {
unsigned int firstIndex = u * numCVInV + (numCVInV - v - 1);
unsigned int lastPeriodicIndex = (numCVInU - degreeU + u) * numCVInV + (numCVInV - v - 1);
if (!controlVertices[firstIndex].isEquivalent(controlVertices[lastPeriodicIndex])) {
formU = MFnNurbsSurface::kOpen;
notOpen = false;
break;
}
}
}
if (formU == MFnNurbsSurface::kOpen) {
formU = MFnNurbsSurface::kClosed;
for (unsigned int v = 0; v < numCVInV; v++) {
unsigned int lastUIndex = (numCVInU - 1) * numCVInV + (numCVInV - v - 1);
if (! controlVertices[numCVInV-v-1].isEquivalent(controlVertices[lastUIndex])) {
formU = MFnNurbsSurface::kOpen;
break;
}
}
}
notOpen = true;
for (unsigned int u = 0; notOpen && u < numCVInU; u++) {
for (unsigned int v = 0; v < degreeV; v++) {
unsigned int firstIndex = u * numCVInV + (numCVInV - v - 1);
unsigned int lastPeriodicIndex = u * numCVInV + (degreeV - v - 1); //numV - (numV - vDegree + v) - 1;
if (!controlVertices[firstIndex].isEquivalent(controlVertices[lastPeriodicIndex])) {
formV = MFnNurbsSurface::kOpen;
notOpen = false;
break;
}
}
}
if (formV == MFnNurbsSurface::kOpen) {
formV = MFnNurbsSurface::kClosed;
for (unsigned int u = 0; u < numCVInU; u++) {
if (! controlVertices[u * numCVInV + (numCVInV-1)].isEquivalent(controlVertices[u * numCVInV])) {
formV = MFnNurbsSurface::kOpen;
break;
}
}
}
Alembic::Abc::FloatArraySamplePtr uKnot = samp.getUKnot();
Alembic::Abc::FloatArraySamplePtr vKnot = samp.getVKnot();
unsigned int numKnotsInU = static_cast<unsigned int>(uKnot->size() - 2);
MDoubleArray uKnotSequences;
uKnotSequences.setLength(numKnotsInU);
for (unsigned int i = 0; i < numKnotsInU; ++i)
{
uKnotSequences.set((*uKnot)[i+1], i);
}
unsigned int numKnotsInV = static_cast<unsigned int>(vKnot->size() - 2);
MDoubleArray vKnotSequences;
vKnotSequences.setLength(numKnotsInV);
for (unsigned int i = 0; i < numKnotsInV; i++)
{
vKnotSequences.set((*vKnot)[i+1], i);
}
// Node creation try the API first
MFnNurbsSurface mFn;
obj = mFn.create(controlVertices, uKnotSequences, vKnotSequences,
degreeU, degreeV, formU, formV,
true, iObject, &status);
// something went wrong, try open/open create
if (status != MS::kSuccess && (formU != MFnNurbsSurface::kOpen ||
formV != MFnNurbsSurface::kOpen))
{
obj = mFn.create(controlVertices, uKnotSequences, vKnotSequences,
degreeU, degreeV, MFnNurbsSurface::kOpen, MFnNurbsSurface::kOpen,
true, iObject, &status);
}
if (status == MS::kSuccess)
{
mFn.setName(surfaceName);
}
else
{
MString errorMsg = "Could not create Nurbs Surface: ";
errorMsg += surfaceName;
MGlobal::displayError(errorMsg);
}
trimSurface(samp, mFn);
return obj;
}