On Mar 8, 2015, at 10:53 PM, Neil Toronto <neil.toro...@gmail.com> wrote:
> If you've ever had the slightest hankering to do some real 3D but avoided it > because of the pain that usually goes with it, try Pict3D. (If it fails to > work, please submit a bug report on the GitHub page.) Got a visualization > project? Try Pict3D. Want to make a game? Try Pict3D's version of Big Bang. > Want to just fool around in 3D space for a bit? Try Pict3D, and report back > on how it goes. I made a version of the game unpossible using pict3d: https://github.com/AlexKnauth/my-unpossible It’s a bit slow and jerky, but that’s probably entirely because I didn’t try too hard to make my end of it fast. If you have any suggestions that would be great. On Mar 9, 2015, at 5:58 PM, Neil Toronto <neil.toro...@gmail.com> wrote: > On 03/09/2015 03:37 PM, Alexander D. Knauth wrote: >> Is there a good way to draw a smooth curved cylinder? > Sure! You could assemble it yourself out of triangles and quads. :) > > OK, maybe that's not "good". It's a fun problem, though, so I gave it a shot. > I've attached my solution. The `parametric-cylinder` function accepts a > function that takes a "time" parameter `t` and returns four values: the > center of the cylinder at time `t`, the first derivative of the function from > `t` to center, the second derivative, and a radius. It should work on any > parametric function that doesn't have any collinear segments. > > You probably want something like the `helix` example. > > An easier-to-use solution would probably derive the first and second > derivatives from samples of the center position. > > Neil ⊥ Thanks! And by the way, for my use case, it was good that I could provide the derivative myself. I ended up using it like this: (parametric-cylinder #:samples 1 (match-lambda [0.0 (values pos dir (dir- new-dir dir) 1/2)] [1.0 (values new-pos new-dir (dir- new-dir dir) 1/2)]) 0.0 1.0) ____________________ Racket Users list: http://lists.racket-lang.org/users
