half edge data structure

hello i am trying to implement a hald edge data structure.

In my project, I have to read a file that contains the geometrical
specifications of a 3d object which has been converted into a
triangular mesh. I have specified the format of the file in a previous
thread -

http://groups.google.co.in/group/comp.lang.c/msg/17f95654400d414d
(ignore the program bit just read about the format of file)

^^ I have stored all this information in a vertex list. Sequentially
in the way they occur. After the coordinates, the file specifies 3
indices into the vertex list(which point to 3 vertices) needed to
define a triangle.

Now I'm successfully able to code a program read the data from the
file
with the help of data structures that I created for vertex, object and
But now, I want to implement adjacency queries for which I need half
edge data structure. I do not understand how to create a half edge
data structure from this plethora of information (i.e. vertex list and
triangle list). I looked on flipcode and found some information about
the structures involved -

struct HE_edge
{

HE_vert* vert; // vertex at the end of the half-edge
HE_edge* pair; // oppositely oriented adjacent half-edge
HE_face* face; // face the half-edge borders
HE_edge* next; // next half-edge around the face

};

struct HE_vert
{

float x;
float y;
float z;

HE_edge* edge; // one of the half-edges emantating from the
vertex

};

struct HE_face
{

HE_edge* edge; // one of the half-edges bordering the face

};

Now my main question : How do I fit all this data into the structures
above ?? Do I need to loop through each vertex in the vertex list and
each triangle in triangle list ??
.

Relevant Pages

  • Re: half edge data structure
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    (comp.lang.c)
  • half edge data structure
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  • Re: half edge data structure
    ... The file specifies the details about the 3d ... to represent the triangle. ... typedef struct { ... edge data structure. ...
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  • Re: 3D Frustum Clipping
    ... Your data structures sound reasonable, ... good way to allow you to focus on the clipping. ... data structure that you are using explicit, ... Remember that first we clip the triangle ...
    (comp.graphics.algorithms)