[apologies to my LJ readers for the lack of cut] Lately I’ve been reading books on gifted children: how to identify them; how to deal with them; what to expect as a parent. Is mini-Elbeno gifted? Without wanting to sound like a competitive parent, and properly considering that it’s still…
LA Moments
Heading west on Sunset (that winding bit just north of the Los Angeles Country Club), when a charcoal grey Lamborghini Murcielago pulls out just ahead of me. Nice. It made a lovely sound and went from zero to 40 in about 2 seconds. Really expensive cars tend to actually be…
Splines and modulation
My efforts to equally subdivide a curve along its length have, in part, been leading to this. First, I extended the sampling to work with splines (made up of cubic Bézier curves with c1 continuity). This shot shows 4 curves put together to form a spline: Next, I wrote some…
And it was done
Since I already had the binary search and interpolation code, it was just a matter of writing different samplers for ellipses and Bézier curves. ;; make a sampler function for a bezier curve (defun make-bezier-sampler (p0 p1 p2 p3) (lambda (k) (decasteljau p0 p1 p2 p3 k))) ;; make a…
More on ellipses
I think I will use the same method as I do for Bézier curves to step along the circumference. Another generalisation I had to make from the circle code is with respect to the normal. For a circle of radius r, centred on the origin, and parameterised by angle θ,…
On ellipses
Having conquered equidistant spacing along a Bézier curve, my thoughts now turn to the same problem for an ellipse. I have solved the problem for a circle of course, which is a special case of an ellipse. One would think that going from a circle to an ellipse would be…
Bore da
Happy St David’s Day to all my Wales-connected friends. I’m not remotely Welsh. But I can say Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch. I suppose it’s been St David’s Day for 8 hours already, actually…
Profiling with SBCL
My Bézier curve code was not optimal, so I decided to learn how to profile with SBCL. In particular, I was not yet doing a binary search of the sampled points, neither was I doing an interpolation to recover the parameter t. Finally, I was sampling the curve at a…
Modern Correspondence
I’ve set aside my usual time for checking on my email. Penis enlargement… penny stocks… pretending to be female… Apparently my gas bill’s ready for an online look, And Amazon have managed (finally) to ship my book. An urban legend warning from some well-intentioned kin: I’ve told them about snopes.com,…
Some interview questions I’m thinking about
I’m thinking about the following questions. They are to be completed using pencil and paper (or marker & whiteboard) only (and for questions 1 and 2, I’d accept the method and not worry about the actual calculated answer). At the moment, only one of them is a question I’ve actually…