This video tutorial explains how to create mesh using Python script.

Vertices must be defined in right order when we want to define correct face.

Let’s imagine that we would like to create following object:

Numbers are marking vertices beginning from 0.

Let’s define them:

faces = ((0,1,2,3), (1,2,6,5), (1,0,4,5), (2,3,7,6), (0,3,7,4), (4,5,6,7)

Just display normals to see whether everything is ok.

As you can see, only few faces have correct normal.

In order to define face correctly use following rule:

Imagine that you’re sitting inside object and you’re looking outside.

You have to define face by naming vertices in clockwise fashion.

Solution is:

faces = ((0,1,2,3), (5,6,2,1), (4,5,1,0), (2,6,7,3), (0,3,7,4),(7,6,5,4))

For more details about Python and Blender pay a visit to blendercookie.com.