[Bf-python] Possible bug with transformations

[Ken Hughes]

Tron Thomas wrote:
> I have run across what I think is a bug in the Python scripting API.  I 
> wanted to run it pass people on this mailing list to make sure.
>  From the default scene, I ran the following script:
> 
> 
> import Blender
> 
> transform = Blender.Object.Get('Cube').getMatrix()
> mesh = Blender.Mesh.Get('Cube')
> 
> for vertex in mesh.verts:
> position = Blender.Mathutils.Vector(vertex.co)
> position.resize4D()
> position *= transform
> position.resize3D()
> print position
> 
> 
> This produced the following output:
> 
> [1.000000, 1.000000, -1.000000](vector)
> [1.000000, -1.000000, -1.000000](vector)
> [-1.000000, -1.000000, -1.000000](vector)
> [-1.000000, 1.000000, -1.000000](vector)
> [1.000000, 0.999999, 1.000000](vector)
> [0.999999, -1.000001, 1.000000](vector)
> [-1.000000, -1.000000, 1.000000](vector)
> [-1.000000, 1.000000, 1.000000](vector)
> 
> 
> I then translated the cube one unit along the X axis and ran the script 
> again.  I got the same output.  It seems that the X component of the 
> outputted vectors should have ranged between zero and 2 rather than -1 
> and 1.
> 
> How correct is this assumption?

You're making a new vector and applying the transform to the copy; 
you're not applying the transform to the mesh vertices.  Try this:

import Blender

transform = Blender.Object.Get('Cube').getMatrix()
mesh = Blender.Mesh.Get('Cube')

for vertex in mesh.verts:
   vertex.co *= transform

Ken