Hi, i''m a Student diong an internship, i have a research assignment where the goal is to make a OpenGL 3D reprisentation of 2D MRI scanner data. I am at the point that i have the model and all, but since the reprisentation is a hart chamber (left ventrikular) it''s in 1 color. The single color prevented seing depth, so i started working with lighting. I have ambient light (works fine), and a stationary spotlight to create a shade in order to get depth. This works good but when i rotate the object arround the x or y axis then i see that the other side does not get illuminated even though the light is shining directly on it. It does however work with rotations arround the Z axis (unless already dark). An example from another company of this viewing module can be found here : http://www.medis.nl/MainFrameProducts/Products/MriMass/MainFrameMASS.htm The bands of the model are made up out of triangle strips and fan''s. and i do not use culling or resize or anything like that that could invalidate the normals. Plz help me,.. i tried everything. I can''t find a solution

I did that, but it didn''t work.
Placing a light at the opposite direction caused the inside of the model to be lighted :S
Any idea what could be causing this ?

I heard something about normals rotating seperatly from verteces
Dunno if that''s the case here.

Here is some of the source code :
All OpenGL related code is in these 2 files

http://asp2.net/ravenmaster/view.c
http://asp2.net/ravenmaster/LVA3DVMain.c