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An IndexedFaceSet is used to define a polygonal shape. For example, it can be used to model a building.
The building geometry is given by a set of points P={P0, P1, ..., Pn}
and a set of polygons F={F0, F1, ..., Fm}. Each point Pi is given by its coordinates Pi=(xi,yi,zi).
Each polygon Fi is defined by a list of m coplanar points (m >=3) given in counterclockwise order:
Fi=(Pi0, Pi1, ... Pim)
Example:
P = {P0, P1, P2, P3, P4, P5, P6, P7, P8}
with
P0 = (-1.0, 0.0, 1.0)
P1 = ( 1.0, 0.0, 1.0)
P2 = ( 1.0, 0.0, -1.0)
P3 = (-1.0, 0.0, -1.0)
P4 = (-1.0, 2.0, 1.0)
P5 = ( 1.0, 2.0, 1.0)
P6 = ( 1.0, 2.0, -1.0)
P7 = (-1.0, 2.0, -1.0)
P8 = ( 0.0, 3.0, 0.0)
F = {F0, F1, F2, F3, F4, F5, F6, F7, F8}
wall:
F0 = (P0, P1, P5, P4)
F1 = (P1, P2, P6, P5)
F2 = (P2, P3, P7, P6)
F3 = (P3, P0, P4, P7)
ground:
F4 = (P0, P3, P2, P1)
roof:
F5 = (P7, P4, P8)
F6 = (P4, P5, P8)
F7 = (P5, P6, P8)
F8 = (P6, P7, P8)
In the IndexedFaceSet the point set P is defined in the Coordinate node. The set of polygons F is defined in the attribute coordIndex. Each polygon is given by a list of point indices followed by -1 to indicate the end of a polygon and the beginning of a new one.
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