By Adam Nagy
If you want to get back the facet geometry of an AcDbSubDMesh entity (simply called “Mesh” in the Properties palette), then you can use either getFaceArray (Returns Level 0 (base) mesh face list array) or getSubDividedFaceArray (Returns smoothed mesh face list array).
The below sample code uses the latter.
void
drawSubDMeshFacets()
{
ads_name name;
AcGePoint3d pt;
int ret = acedEntSel(
_T("\nSelect a SubD Mesh: "), name, asDblArray(pt));
if (ret != RTNORM)
{
acutPrintf(_T("\nNothing selected"));
return;
}
AcDbObjectId id;
acdbGetObjectId(id, name);
if (id.objectClass() != AcDbSubDMesh::desc())
{
acutPrintf(_T("\nSelected entity is not a SubD Mesh"));
return;
}
AcDbObjectPointer<AcDbSubDMesh> mesh(id, AcDb::kForRead);
AcGePoint3dArray vertices;
mesh->getSubDividedVertices(vertices);
AcArray<Adesk::Int32> faces;
mesh->getSubDividedFaceArray(faces);
// The content of the faces list is like so:
// [number of vertices of next face],
// <vertexIndex1, vertexIndex2, etc>,
// e.g. [4], <1, 2, 3, 4>, [3], <1, 2, 3>, etc
AcDbDatabase * pDb =
acdbHostApplicationServices()->workingDatabase();
AcDbBlockTableRecordPointer
ms(ACDB_MODEL_SPACE, pDb, AcDb::kForWrite);
for (int numVertices = 0, i = 0;
i < faces.length(); i += numVertices + 1)
{
numVertices = faces.at(i);
// Let’s draw the edges of the face
for (int j = 0; j < numVertices; j++)
{
AcGePoint3d pt1 =
vertices.at(faces.at(i + j + 1));
AcGePoint3d pt2 =
vertices.at(faces.at(i + ((j + 1) % numVertices) + 1));
AcDbObjectPointer<AcDbLine> line;
line.create();
line->setStartPoint(pt1);
line->setEndPoint(pt2);
ms->appendAcDbEntity(line);
}
}
}
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