Flat, Gouraud, & Phong Shading

Phong Reflection Model

Calculates material lighting intensity $I$ by combining three terms:

• Ambient: General background glow.
• Diffuse: Lambertian cosine law reflection depending on the angle between normal and light ($N \cdot L$).
• Specular: Shiny highlights ($R \cdot V^n$) based on shininess exponent $n$.

Interpolation Styles

• Flat Shading: Evaluates color once per polygon face (causes faceted appearance).
• Gouraud Shading: Computes color at vertices and interpolates across the polygon face.
• Phong Shading: Interpolates normals across the face and computes illumination per pixel (produces best specular highlights).