Shading
Not quite Phong-Shading, but at least my spheres are shaded now. Implemented the possibility for multiple light soures, different light intensities, switchable shadows and especially shading (based on the simple Lambertian-Model):
A video showing how changing the light intensity alters the scene is here:
PS: While I was developing, I played a bit with the colouring. One of the better results were
