Hello!
I'm working on a custom toon shader. As a basis I want to use the lambert lighting model as described in the tutorial embedded below. To test this I created a very simple scene with a sphere placed at the origin, a point light and a material with the material builder applied to the sphere (see image below).
Now, here's the problem: The shading of the sphere is incorrect as soon as the point light has negative coordinates. It seems as if the surface_global's P and N are expressed in a different space compared to the point light's position. This happend with Mantra as well as Redshift (where I used the same setup as in the video below, apart from getting the light's position through a constant and channel references). Am I wrong to assume that P is the world position of the current point being shaded and N is it's normalised normal? Is this the wrong way to get the light position into the shader? I spent some time testing and searching on the internet but I couldn't find anything that clarified these quesitons sufficiently for me.
custom_lambert.hipnc