CG Class 9, Mon 2017-09-25

1   SIGGRAPH 2017 videos

SIGGRAPH is the world's leading CG conference. I'll show various videos from it.

  1. New tech.

2   Text chapter 3 programs

Now, we'll see in more detail how some programs in http://www.cs.unm.edu/~angel/WebGL/7E/03/ work.

  1. squarem

3   Slides

We'll continue with the textbook powerpoint slides.

  1. 4_1 Input and Interaction
  2. 4_2 Animation
  3. 4_3 Working with Callbacks

4   3D rotation

  1. Now we're starting a module on 3D rotations.
  2. My note on 3D rotation.
    1. All rigid transformations in 3D that don't move the origin have a line of fixed points, i.e., an axis, that they rotate around.
    2. deriving the vector formula for a rotation given the axis and angle
    3. computing the matrix from a rotation axis and angle
    4. testing whether a matrix is a rotation
    5. if it is, then finding the axis and angle.

5   Euler and angles and Gimbal lock

  1. http://www.youtube.com/watch?v=rrUCBOlJdt4&feature=related Gimble Lock - Explained.

    One problem with Euler angles is that multiple sets of Euler angles can degenerate to the same orientation. Conversely, making a small rotation from certain sets of Euler angles can require a jump in those angles. This is not just a math phenomenon; real gyroscopes experience it.

  2. http://en.wikipedia.org/wiki/Gimbal_lock

  3. What is Gimbal Lock and why does it occur? - an animator's view.

6   Homework 4 online

  1. Homework 4 is online; due next Mon 2359. Changed to next Thurs.