CG Lecture 21, Mon 2016-10-24

W Randolph Franklin, RPI

  1. This Wed will be a regular lecture.

  2. There will be no classes next week.

  3. Spring course to consider: ECSE-4740 Applied Parallel Computing for Engineers. Its instructor is excellent.

  4. RPI has a long history in Computer Graphics. E.g. Prof Mike Wozny, Head of ECSE, was one of the founders of IEEE Computer Graphics and Applications, which printed the article by Maureen Stone that I presented last time.

  5. Iclicker questions.

  6. 8_2 Lighting in WebGL.

  7. shadedSphere1, 2 etc programs.

  8. 8_3 Polygonal Shading.

  9. 8_4 Per Vertex and Per Fragment Shading.

  10. 8_E3 Marching Squares.

    Will be omitted.

  11. Computing surface normals.

    1. For a curved surface, the normal vector at a point on the surface is the cross product of two tangent vectors at that point. They must not be parallel to each other.
    2. If it's a parametric surface, partial derivatives are tangent vectors.
    3. A mesh is a common way to approximate a complicated surface.
    4. For a mesh of flat (planar) pieces (facets):
      1. Find the normal to each facet.
      2. Average the normals of the facets around each vertex to get a normal vector at each vertex.
      3. Apply Phong (or Gouraud) shading from those vertex normals.