The book omitted the explanation of the constructor of hyperboloid.

Could someone give some explanations about:

  1. Why the arguments are two points?
  2. What are the meanings of ah and ch?
  3. Why is there a while loop?

1 Answer 1

  1. They must define it as a surface of revolution of a line segment.
  2. From the comments, they are probably the a and c coefficients of the canonical hyperboloid equation. With a surface of revolution, a == b so no need to store b separately.
  3. It's clearly related to figuring out ah and ch from the line segment. I can't say more precisely without working out the math involved. I'll leave that to someone with more free time.
  • $\begingroup$ A surface of revolution of a line segment would be a disk, cylinder, or cone, no? I can't see how you would get a hyperboloid; it should be a surface of revolution of a hyperbola. I'm guessing the hyperbola is fit to pass through the two points, or something like that. $\endgroup$ May 23, 2017 at 15:13
  • 2
    $\begingroup$ @NathanReed It's not intuitive at all but it is possible. Look at the diagrams on the right side of the wikipedia entry. $\endgroup$
    – Olivier
    May 23, 2017 at 22:31

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