81 lines
3.1 KiB
Plaintext
81 lines
3.1 KiB
Plaintext
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/** \mainpage
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The Visualization and Computer Graphics Library (VCG for short) is
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a open source portable C++ templated library for manipulation, processing
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and displaying with OpenGL of triangle and tetrahedral meshes.
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The library, composed by more than 50k lines of code,
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is released under the GPL license, and it is the base of most of the
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software tools of the <b>Visual Computing Lab</b> of the Italian National Research Council Institute ISTI
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(http://vcg.isti.cnr.it), like metro and shadevis.
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The VCG library was built to manage triangular meshes, so most of the classes
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and algorithms it contains are related to such object. This is especially true
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for the things that are in the "mesh" folder of the tree. This document
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basically explains how the concept of mesh is implemented, i.e. what the "type"
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of a mesh is and how it can be obtained, how the connectivity of the mesh is
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stored and how it is used to visit the mesh. This part of the library is self
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contained, only standard libraries are included, as STL (which are intensively
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used all over the code).
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\section Intro Point3 as an example of the style
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We won't going through all of the files and classes of the library to show how
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it is built. You will find most of the information in the code as comments, and
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when understood the implementation flavor, you won't even need the comments.
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The definition of class Point3 looks like this:
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\code
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template <class T> class Point3 {
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public:
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Point3() { }
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~Point3() { }
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private:
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T _v[3];
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// ....
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// ....
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public:
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T & X(){return v[0];}
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T & Y(){return v[1];}
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T & Z(){return v[2];}
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// ...... operators
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};
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\endcode
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You will find that most of (if not all of) the classes have some template
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parameters. In this case it is used to say which type is used as coordinate
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(most of the times it will be float or double, but it can be any type
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implementing the operator used in the bodies of Point3 operators). Another
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common characteristic is the access method to the data (in this case v[3]),
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which are always defined as private member.
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\subsection ind Indexing and numbering conventions
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Vertex edges, and wedges are ordered according the following convention: face should be seen their vertexes counterclockwise, edge \c i is the one formed by vertex \c i and \c i+1.
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\image html img/triord.png "Naming conventions for vertexes and edges"
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For a tetrahedrdon we assume that it is \i well-oriented when the vertex \c 0 sees the other vertexes \c 1 2 3 in a counter-clockwise manner
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\subsection fft Face-face Topology
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With the face-face topology every face has three pointers to Face and three
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integers. Given a face with FF topology the pointer \c f.F(i) points to the face that shares the edge \c i with
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\c f , and the integer \c f.Z(i) tells the number of edge \c f.i as seen from face
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\c f.F(i) (see Figure ).
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If the edge \c f.i is on the mesh border, \c f.F(i)==f. The following
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proposition holds: \n
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\code
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(f.F(i)== &f) || (f.F(i))->F(f.Z(i))== &f
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\endcode
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some text
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\image html img/ff.png "Example of face-face topology"
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*/
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