[ Changes in definition of TriMesh: PART II ]
Note: No changes to existing code need be the done, this mod
should be fully backward compatible
Old way to define a TriMesh ==============
struct MyMesh: public vcg::tri::TriMesh< vector<MyVertex> , vector <MyFace> >{};
new ways to define a TriMesh ==============
struct MyMesh: public vcg::tri::TriMesh< CONT1 >{};
struct MyMesh: public vcg::tri::TriMesh< CONT1 , CONT2>{};
struct MyMesh: public vcg::tri::TriMesh< CONT1 , CONT2, CONT3>{};
where CONT[i] can be vector< [MyVertex | MyEdge | MyFace ] >
(the order is unimportant)
Note for the developers: the change to make to existing projects is very little
but strictly necessary to compile. This change IS NOT backward compliant.
==== OLD ==== way to define a TriMesh:
// forward declarations
class MyVertex;
class MyEdge;
class MyFace;
class MyVertex: public VertexSimp2 < MyVertex, MyEdge, MyFace, vertex::Coord3f,...other components>{};
class MyFace: public FaceSimp2 < MyVertex, MyEdge, MyFace, face::VertexRef,...other components>{};
class MyMesh: public TriMesh<vector<MyVertex>,vector<MyFace> >{};
==== NEW ==== way to define a TriMesh:
// forward declarations
class MyVertex;
class MyEdge;
class MyFace;
// declaration of which types is used as VertexType, which type is used as FaceType and so on...
class MyUsedTypes: public vcg::UsedType < vcg::Use<MyVertex>::AsVertexType,
vcg::Use<MyFace>::AsFaceType>{};
class MyVertex: public Vertex < MyUsedTypes, vertex::Coord3f,...other components>{};
class MyFace: public Face < MyUsedTypes, face::VertexRef,...other components>{};
class MyMesh: public TriMesh<vector<MyVertex>,vector<MyFace> >{};
===== classes introduced
[vcg::UsedType] : it is a class containing all the types that must be passed to the definition of Vertex, Face, Edge... This
class replaces the list of typenames to pass as first templates and the need to specify the maximal simplicial. So
<MyVertex, MyEdge, MyFace becomes <MyUsedTypes<
and
VertexSimp2 becomes Vertex
[vcg::Use] : an auxiliary class to give a simple way to specify the role of a type
Note 2: the order of templates parameters to vcg::UsedTypes is unimportant, e.g:
class MyUsedTypes: public vcg::UsedType <vcg::Use<MyVertex>::AsVertexType,
vcg::Use<MyEdge>::AsEdgeType,
vcg::Use<MyFace>::AsFaceType>{};
is the same as:
class MyUsedTypes: public vcg::UsedType <vcg::Use<MyFace>::AsFaceType,
vcg::Use<MyEdge>::AsEdgeType,
vcg::Use<MyVertex>::AsVertexType>{};
Note 3: you only need to specify the type you use. If you do not have edges you do not need
to include vcg::Use<MyEdge>::AsEdgeType in the template list of UsedTypes.
==== the Part II will be a tiny change to the class TriMesh it self.
with both old and new version. The fixes include:
- dot product: vec0 * vec1 => vec0.dot(vec1) (I added .dot() to the old Point classes too)
- Transpose: Transpose is an Eigen type, so we cannot keep it if Eigen is used. Therefore
I added a .tranpose() to old matrix classes, and modified most of the Transpose() to transpose()
both in vcg and meshlab. In fact, transpose() are free with Eigen, it simply returns a transpose
expression without copies. On the other be carefull: m = m.transpose() won't work as expected,
here me must evaluate to a temporary: m = m.transpose().eval(); However, this operation in very
rarely needed: you transpose at the same sime you set m, or you use m.transpose() directly.
- the last issue is Normalize which both modifies *this and return a ref to it. This behavior
don't make sense anymore when using expression template, e.g., in (a+b).Normalize(), the type
of a+b if not a Point (or whatever Vector types), it an expression of the addition of 2 points,
so we cannot modify the value of *this, since there is no value. Therefore I've already changed
all those .Normalize() of expressions to the Eigen's version .normalized().
- Finally I've changed the Zero to SetZero in the old Point classes too.
ganovelli
Paolo Cignoni
Marco Di Benedetto
Nico Pietroni
Federico Ponchio
mtarini