Exhibit #3: Vertex Phong Lighting

What we did here

We upgraded the lighting model from Lambert to Phong:

• We added new uniforms for specularColor (a 3-vector like the diffuse color) and phongExponent (a float).
• The lighting computations in the vertex shader include the specular component as well as the diffuse component.
• The varying variable surfaceColor and the fragment shader remain unchanged.