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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. <X3D id="shapedata" width="600px" height="600px" style="float:left"> <Scene> <Shape> <Appearance> <Material diffuseColor="0.5 0.5 0.5"> </Material> </Appearance> <IndexedFaceSet solid="true" ccw ="true" coordIndex=" 0 1 5 4 -1 1 2 6 5 -1 2 3 7 6 -1 3 0 4 7 -1 0 3 2 1 -1 7 4 8 -1 4 5 8 -1 5 6 8 -1 6 7 8 -1"> <Coordinate point="-1 0 1, 1 0 1, 1 0 -1, -1 0 -1, -1 2 1, 1 2 1, 1 2 -1, -1 2 -1, 0 3 0 " > </Coordinate> </IndexedFaceSet> </Shape> </Scene> </X3D> |