SHADING (How does it all happen?)

• Spotlights
• specifying using OpenGL
• Major Problems
• Recursive Subdivision

LIGHTING Using OpenGL

• Select a Lighting Model:    glLightModel    
  • select global light
  • select whether viewpoint local or infinite
  • select whether lighting should be done differently for fron and back faces
  • select whether or not to separate the specular color and apply separately
    
• Enable Lighting in General:      glEnable(GL_LIGHTING)
• Specifying Light Sources 
• For each Light Source        glLight
  • Specify type of light:
    • directional
  • positional
    • positional spotlight

      SPOTLIGHTS WITH OPENGL

      • Must specify normalized normal for face
      • Must specify positional light with the usual attributes (position, diffuse, ambient, specular components)
      • Must specify spot cutoff angle
      • Must specify spot exponent
  • Specify attenuation (only if positional light)
  • Enable that light source:  glEnable(GL_LIGHTi)
    
    
• Moving Light Sources (see pages 397-398 in Hill):
  • independent of the camera
  • along with the camera
    
    
• Objects (For each Face of the Object):
• Provide the Normal to the Face
• Specify Materials Properties:      glMaterial
• ambient coefficient
• diffuse coefficient 
• specular coefficient
• Phong Exponent 
• emissive color
  
  

REFERENCE(S):

Computer Graphics Using OpenGL (Hill): Chapter 8
 OpenGL Programming Guide: Chapter ? (Lighting)  *Note:  in HTML version, it is Ch.6; in PDF format, it is Ch.5
OpenGL Manual/v.1.2:  Chapter 2 (Subdivision, Recursive Subdivision)