I’m trying to export faces for a package that ‘kind of’ supports 3d…as in 3d postcards, so position, rotation and scale in 3d and that’s about it. faces are drawn in 2d.

If I have a face in 3d, how can I get it’s rotation on x y and z,

‘unrotated’ so that all vertices on one dimension have value 0 ?

I’ve tried to understand this http://en.wikipedia.org/wiki/Rotation_matrix#Rotation_matrix_given_an_axis_and_an_angle

but I don’t think I got it, or I don’t use it properly.

Here’s a test

import Blender

from Blender import *

import math

from math import sin,cos,radians,degrees

```
def getRotMatrix(n):
c = cos(0)
s = sin(0)
x2 = n.x*n.x
y2 = n.y*n.y
z2 = n.z*n.z
l1 = x2+(1-x2)*c, n.x*n.y*(1-c)+n.z*s, n.x*n.y*(1-c)-n.y*s
l2 = n.x*n.y*(1-c)-n.z*s,y2+(1-y2)*c,n.x*n.z*(1-c)+n.x*s
l3 = n.x*n.z*(1-c)+n.y*s,n.y*n.z*(1-c)-n.x*s,z2-(1-z2)*c
m = Mathutils.Matrix(l1,l2,l3)
return m
scn = Scene.GetCurrent()
ob = scn.objects.active.getData(mesh=True)#access mesh
out = ob.name+'
'
#face0
f = ob.faces[0]
n = f.v[0].no
out += 'face: ' + str(f)+'
'
out += 'normal: ' + str(n)+'
'
m = getRotMatrix(n)
m.invert()
rvs = []
for v in range(0,len(f.v)):
out += 'original vertex'+str(v)+': ' + str(f.v[v].co) + '
'
rvs.append(m*f.v[v].co)
out += '
'
for v in range(0,len(rvs)):
out += 'rotated vertex'+str(v)+': ' + str(rvs[v]) + '
'
f = open('out.txt','w')
f.write(out)
f.close
```

And here are a few outputs:

from a default plane with vertices rotated 30 degrees on x axis:

```
Plane.008
face: [MFace (0 3 2 1) 0]
normal: [0.000000, -0.499985, 0.866024](vector)
original vertex0: [1.000000, 0.866025, 0.500000](vector)
original vertex1: [-1.000000, 0.866026, 0.500000](vector)
original vertex2: [-1.000000, -0.866025, -0.500000](vector)
original vertex3: [1.000000, -0.866025, -0.500000](vector)
rotated vertex0: [1.000000, 0.866025, 1.000011](vector)
rotated vertex1: [-1.000000, 0.866026, 1.000012](vector)
rotated vertex2: [-1.000000, -0.866025, -1.000012](vector)
rotated vertex3: [1.000000, -0.866025, -1.000012](vector)
```

from the first face of suzanne’s face:

```
Suzanne.001
face: [MFace (46 0 2 44) 0]
normal: [0.987976, -0.010102, 0.154088](vector)
original vertex0: [0.468750, 0.242188, 0.757813](vector)
original vertex1: [0.437500, 0.164063, 0.765625](vector)
original vertex2: [0.500000, 0.093750, 0.687500](vector)
original vertex3: [0.562500, 0.242188, 0.671875](vector)
rotated vertex0: [0.468750, 0.242188, -0.795592](vector)
rotated vertex1: [0.437500, 0.164063, -0.803794](vector)
rotated vertex2: [0.500000, 0.093750, -0.721774](vector)
rotated vertex3: [0.562500, 0.242188, -0.705370](vector)
```

hints ?