任何人都可以为我解释FBX格式吗？ [英] can anyone explain the FBX format for me?

问题描述

我使用notepad ++查看FBX模型的数据结构，但是我有一些问题需要了解。以下是位于（0,0,0）中的多维数据集（side = 10）的一些信息，任何人都可以告诉我这些成员是什么意思？谢谢！

 顶点：* 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 
} 
边：* 18 {
a：0,1,2,3,4,6,7,8,9,10,13,14,16,19,20,25,26,32 
} 
法线：* 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 
} 
  

解决方案

即使不了解FBX格式，您至少可以做出一些非常合理的猜测：

1. 顶点下的24个值是多维数据集的8个顶点（3个值代表一个顶点）。




2. PolygonVertexIndex 下的36个值是顶点索引（引用顶点的值
   

3. 边缘下的24个值是多维数据集的12边的顶点索引。




4. Normals 是12个三角形的每个三角形角的36个法线（3个值代表一个法向量）。




5. UV 是12个纹理坐标（2个值代表一个纹理坐标对）。




6. UVIndex 是多维数据集的36个三角形角的纹理坐标索引（引用 UV 的值）。

   / li>
   

我认为这些是假设是相当合理的，虽然我不知道为什么 PolygonVertexIndex 数组包含负值（每个三角形的每个第三个索引似乎都是负数）。也许指示多边形的最后一个索引，所以你可以有多边形不需要三角形。

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
} 

解决方案

Even with no knowledge of the FBX format you can at least make some very reasonable guesses:

1. The 24 values under Vertices are the 8 vertices of the cube (with 3 values representing one vertex).

2. The 36 values under PolygonVertexIndex are the vertex indices (referencing the values from Vertices) for the 12 triangles making up the 6 faces of the cube.

3. The 24 values under Edges are the vertex indices of the 12 edges of the cube.

4. The 108 values under Normals are the 36 normals for each of the triangle corners of the 12 triangles (with 3 values representing one normal vector).

5. The 24 values under UV are 12 texture coordinates (with 2 values representing one texture coordinate pair).

6. The 36 values under UVIndex are the texture coordinate indices (referencing the values from UV) for the 36 triangle corners of the cube.

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.

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