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Unformatted text preview: 23 Polygonal Meshes ■ many algorithms assume triangular meshes ◆ hardware support ◆ always convex ◆ always planar ✦ polygon normal vector easy to compute N N n P P P P N H H H H = − × − = ) ( ) ( 2 1 24 Polygonal Meshes: Per Vertex Normal Vectors ■ a mesh usually approximation for smooth surface ◆ for shading want normal vector of smooth surface ✦ store this information only at mesh vertices • example: normal vectors shown as arrows, vertices as dots • important: normal vectors are perpendicular to “true” smooth surface ■ usually most convenient to store normalized (unit) normal vectors 25 Polygonal Meshes: Operations ■ rendering ■ simplification ◆ given a mesh, compute a new mesh that looks the same as the old mesh but has fewer vertices and faces ■ smoothing ◆ given a mesh, compute a new mesh that looks smoother than the old mesh ■ animation or warping ■ slicing ◆ cut a mesh into two or more meshes 26 Polygonal Meshes: Operations (cont) ■...
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 Winter '12
 BURTON
 Algorithms, Data Structures, Trigraph, Polyhedron, Polygonal Meshes

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