Structure and pseudocode
The face and vertex records are relatively simple, while the edge record is more complex.
- For each vertex, its record stores only the vertex's position (e.g. coordinates) and a reference to one incident edge. The other edges can be found by following further references in the edge.
- Similarly each face record only stores a reference to one of the edges surrounding the face. There is no need to store the direction of the edge relative to the face (CCW or CW) as the face can be trivially compared to the edge's own left and right faces to obtain this information.
- Finally, the structure of the edge record is as follows. An edge is assumed to be directed. The edge record contains two references to the vertices that make up the endpoints of the edge, two references to the faces on either side of the edge, and four references to the previous and next edges surrounding the left and right face.
In short, the edge record has references to all its adjacent records, both when traversing around an adjacent vertex or around an adjacent face.
class Edge { Vertex *vert_origin, *vert_destination; Face *face_left, *face_right; Edge *edge_left_cw, *edge_left_ccw, *edge_right_cw, *edge_right_ccw; } class Vertex { float x, y, z; Edge *edge; } class Face { Edge *edge; }
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