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…
Experimenting with (cubic) Bézier subdivision
As you know, a Bézier curve (here meaning specifically a cubic Bézier) is often used for drawing all kinds of things in vector graphics. It has the nice property that the endpoints and control points form a bounding box, and deCasteljau’s algorithm is a nice numerically stable way of evaluating…
Sneak preview
This is a sneak peek at my current personal project. A bit of computerised heraldry. (“Sable a [ordinary] ermine.” Left to right, top to bottom: chief, fess, pale, cross, bend, bend sinister, chevron, saltire. Yeah, I know; charges on a bend should be bendwise. It’s a work in progress.)
Book sale time again
Last night I got an email from the library mailing list about another book sale this morning. We snagged a lot of books, including many SF paperbacks. Mini-Elbeno also got a ton of new titles. Not many computer titles this time around, but I got a book on python and…
Life defined by Lunch
I am a creature of habit and habitual comforts. Never more so than at lunchtime. I’m also a big fan of breakfast, it’s true, and I couldn’t really care less about dinner most of the time. But lunch is where the routine kicks in. I could happily eat the same…