Catmull–Clark subdivision surface: Difference between revisions
Catmull–Clark subdivision surface (view source)
Revision as of 20:10, 1 September 2010
, 13 years agotentative J implementation
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(tentative J implementation) |
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Line 42:
For edges and vertices not next to a hole, the standard algorithm from above is used.
=={{header|J}}==
<lang j>havePoints=: e."1/~ i.@#
catmullclark=:3 :0
'mesh points'=.y
face_point=: avg"2 mesh{points
point_face=: |: mesh havePoints points
avg_face_points=: point_face avg@#"1 2 face_point
edges=: ~.,/meshEdges=:mesh /:~@,"+1|."1 mesh
edge_point=: avg"2 edges{points
point_edge=: |: edges havePoints points
avg_mid_edges=: point_edge avg@#"1 2 edge_point
n=: +/"1 point_edge
'm3 m2 m1'=:(2,1,:n-3)%"1 n
new_coords=: (m1 * points) + (m2 * avg_face_points) + (m3 * avg_mid_edges)
pts=: face_point,edge_point,new_coords
c0=:(#edge_point)+e0=:#face_point
msh=:(,c0+mesh),.(,e0+edge i. meshEdges),.((#i.)~/$mesh),.,e0+_1|."1 edge i. meshEdges
msh;pts
)</lang>
Example use:
<lang j>NB.cube
points=: _1+2*#:i.8
mesh=:1 A."1 I.(,1-|.)8&$@#&0 1">4 2 1
catmullclark mesh;points
┌──────────┬─────────────────────────────┐
│22 6 0 9│ 1 0 0│
│23 7 0 6│ 0 1 0│
│25 8 0 7│ 0 0 1│
│24 9 0 8│ 0 0 _1│
│20 10 1 12│ 0 _1 0│
│21 11 1 10│ _1 0 0│
│25 8 1 11│ 1 _1 0│
│24 12 1 8│ 1 0 1│
│19 13 2 14│ 1 1 0│
│21 11 2 13│ 1 0 _1│
│25 7 2 11│ _1 1 0│
│23 14 2 7│ 0 1 1│
│18 15 3 16│ 0 1 _1│
│20 12 3 15│ _1 0 1│
│24 9 3 12│ 0 _1 1│
│22 16 3 9│ _1 0 _1│
│18 17 4 16│ 0 _1 _1│
│19 14 4 17│ _1 _1 0│
│23 6 4 14│_0.555556 _0.555556 _0.555556│
│22 16 4 6│_0.555556 _0.555556 0.555556│
│18 17 5 15│_0.555556 0.555556 _0.555556│
│19 13 5 17│_0.555556 0.555556 0.555556│
│21 10 5 13│ 0.555556 _0.555556 _0.555556│
│20 15 5 10│ 0.555556 _0.555556 0.555556│
│ │ 0.555556 0.555556 _0.555556│
│ │ 0.555556 0.555556 0.555556│
└──────────┴─────────────────────────────┘</lang>
=={{header|Mathematica}}==
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