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can anyone explain the FBX format for me?

i use notepad++ to see the data structure of FBX model but i have some problems understanding it. Here is some info of a cube(side = 10) located in (0,0,0), can anyone tell me what do these members mean? THANKS!

Vertices: *24 {
a: -5,-5,0,5,-5,0,-5,5,0,5,5,0,-5,-5,10,5,-5,10,-5,5,10,5,5,10
} 
PolygonVertexIndex: *36 {
a: 0,2,-4,3,1,-1,4,5,-8,7,6,-5,0,1,-6,5,4,-1,1,3,-8,7,5,-2,3,2,-7,6,7,-4,2,0,-5,4,6,-3
} 
Edges: *18 {
a: 0,1,2,3,4,6,7,8,9,10,13,14,16,19,20,25,26,32
} 
Normals: *108 {
a: 0,0,-1,0,0,-1,0,0,-1,0,0,-1,0,0,-1,0,0,-1,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,-        1,0,0,-1,0,0,-1,0,0,-1,0,0,-1,0,0,-   1,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,-1,0,0,-1,0,0,-1,0,0,-1,0,0,-1,0,0,-1,0,0
} 

UV: *24 {
a: 0,0,1,0,0,1,1,1,0,0,1,0,0,1,1,1,0,0,1,0,0,1,1,1
} 
UVIndex: *36 {
a: 9,11,10,10,8,9,8,9,11,11,10,8,4,5,7,7,6,4,0,1,3,3,2,0,4,5,7,7,6,4,0,1,3,3,2,0
} 
like image 540
yvetterowe Avatar asked Oct 12 '11 07:10

yvetterowe


1 Answers

I think these assumptions are quite reasonable, though I'm not sure why the PolygonVertexIndex array contains negative values (it seems every third index of each triangle is negative). Maybe to indicate the last index of a polygon, so you can have polygons which need not be triangles.

The one with the negative value represents the last vertex indeed.

To find out witch vertex this is, you have to negate it and subtract 1 from that value.

For example, -4 represents 3 ((-4)*(-1) - 1)

like image 51
Harlequin Avatar answered Nov 12 '22 23:11

Harlequin