ER Polyeder Poly ID N Hull M Faces

用边界表示法描述的多面体E-R设计 Polyeder Poly. ID N Hull M Faces Face. ID N Boundaries M Edges Edge. ID N Start. End M Vertices Vertex. ID

多面体的关系模型示例 Hull Polyeder Poly. ID Volume … Poly. ID Face. ID … “cubo#5” … … 1000. 00 … … “cubo#5” … “f 1” “f 2” … “f 6” … Faces Face. ID … “f 1” “f 2” … “f 6” … Circumferenc e … … 40. 00 … … … … Boundaries Face. ID Edge. ID … “f 1” … “f 6” … … “e 1” “e 2” “e 3” “e 4” … … …

关系模型的缺陷 1续 Select distinct p. Poly. ID, v. Vertex. ID, v. X, v. Y, v. Z From Polyeder p, Hull h, Boundaries b, Start. End s Vertices v Where p. Volume > 10 and p. Poly. ID = h. Poly. ID and p. Face. ID = b. Face. ID and b. Edge. ID = s. Edge. ID and s. Vertex. ID = v. Vertex. ID

例 指针Edge Vertices指向的Join查询结果是不 能直接被更新的 Exec sql declare Edge Vertices cursor for select s. Edge. ID, v. Vertex. ID, v. X, v. Y, v. Z from Start. End s, Vertices v where s. Vertex. ID=v. Vertex. ID;

exec sql declare Edge. To. Vertices cursor for select * from Start. End; exec sql open Edge. To. Vertices ; while(1) /*Iterate over the Edge. To. Vertices crusor*/ { exec sql fetch Edge. To. Vertex into: E#, : V#; exec sql select X, Y, Z /*read the coordinates*/ into : Xvar, : Yvar, : Zvar from Vertices where s. Vertex. ID= : V#; …… exec sql update Vertices set…; /*perform modifications*/ }

例：阻抗失配可视化 Application A Application B rotate Polyeder rotate Faces Hull Boundaries Edges Vertices Start. End

Application A Application B some. Cuboid. rotate(x, Ф); W: =some. Cuboid. weight; rotate scale weight translate spec. Weight volume object base …