1. School of Computer Science
Computer Graphics
School of Computer Science
University of Seoul
Minho Kim

2. Blinn-Phong Shading Model
Assumed to be broken into (independent) RGB components
Materials characterized by the percentage of the incoming RGB components that are reflected
Four (independent) components
Ambient: bounced & scattered many times, no direction known, lightpos/viewer-independent
Diffuse: bounced & scattered in all directions, viewer-independent, lightpos-dependent
Specular: reflected in a preferential direction, lightpos/viewer-dependent
Emissive: emits light, not affected by lights, not affect lighting

3. Blinn-Phong Shading Model (cont'd)
Meaning of four components (ambient, diffuse, specular, emissive) for each color
Lights – intensity
Materials – reflected proportion

4. OpenGL Lighting Blinn-Phong shading model + Gouraud shading
OpenGL lighting equation
Materials can be set for front/back face seperately
Lights transformed by modelview matrix (not projection matrix)
No shadow (only a vertex-light pair is considered)
Reflected light not considered anymore

5. Programming Lighting enabled – glEnable(GL_LIGHTING) For each light
Turned on – glEnable(GL_LIGHT#)
Set up (type, position, intensity of each component) – glLight*
For each object (triangle)
Material (per face & component) – glMaterial*
Normal vectors – glNormal*
Requres unit normal vector – GL_NORMALIZE, GL_RESCALE_NORMAL