Non-Global Illumination Models
•Hidden surface removal means polygons you can’t see are not rendered (both those blocked and those that are back-facing – eliminates >50%)
•Non-global means that we look at each polygon in isolation, no shadows or interobject reflection.   Crude but fast model, standard in graphics cards
•Flat shading: light calculated once for each polygon, as a function of the angle between its surface normal and the light source (the “faceted look”)
•Gouraud shading (after Henri Gouraud): average intensity across neighboring polygons to create smooth gradients between them.
•Phong shading adds specular part by averaging normals, not intensities
•
Phong (note highlights)
Flat
Flat
Gouraud
Blinn, Lambert—these are n’t some kind of real-world plastics—these are people who developed algorithms for the types of lighting shown.

These all fast—real time now (although to when I started doing 3D!)--wireframe