I'm currently making a small 3D renderer and I got stuck in Phong shading.
My questions are:
Into which space should the light coordinate be converted?
I have my light position at world coordinates (0,0,0). I'd like to calculate "phong shading" after converting all the vertices to screen space (viewport). So Should I convert the light position to screen space too?
Is there a faster way to calculate Phong shading with normal interpolation if the camera's position equals the light's position?