Help needed calculating vertex normals...

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fredborg

You simply need to average the normals of the 3 "old" vertices, like this:

norm_x_of_centre_vert# = (norm_x_of_vert_0 + norm_x_of_vert_1 + norm_x_of_vert_2)/3.0
etc.

The reason the normals need to have a length of 1, is that when DirectX calculates the lighting on a mesh, it uses the normals straight out the bag, without unifying them first. Therefore if your normals have a different length the lighting will be either dimmer (length<1.0) or more intense (length>1.0).

Edit: Ohh, you're doing edge subdivisions...Then it's like this::

norm_x_of_centre_vert# = (norm_x_of_vert_0 + norm_x_of_vert_1)/2.0
etc.

And make sure your values are all floats!

Fredborg