Plaidophile

A lot of folks out there know about the Mandelbrot set. But that knowledge is often based on pretty abstract stuff, and is limited to the fractal as a two-dimensional thing that doesn't really make much sense. The other day I decided to screw around with some basic GPU programs, and I figured I'd finally write some stuff about this.

This is of course very basic to anyone who has studied fractals before, but the description of what's going on is largely secondary in this case.

(Warning: There are a lot of very large images in this post.)

A while ago I learned about an interesting language called Vala, which is basically C++ if it were redesigned from the ground up with only the good parts of C++, plus useful parts of other more-modern languages like C# and JavaScript. Every now and then I look at the tutorial again and it's just getting better and better. And it is designed to maintain ABI compatibility with C, and actually is just a front-end that generates and compiles C code, meaning it's also perfectly-suited for embedded programming, especially on platforms where C++ has been stupidly hobbled (such as Android NDK).

I especially like the way it handles generics, the way all Vala references are equivalent to boost::shared_ptr (with a keyword to make a reference weak - without any need to explicitly lock it), the way that you can still do explicit memory management if you need to (only with a very nicely-implemented equivalent of std::auto_ptr to make even that stuff easier), it supports contract-based programming features (including requiring explicit nullability for object parameters), and that it supports true closures (unlike Java's quasi-closures) with a syntax that isn't ridiculously horrible (unlike in Javascript, C99, or C++0xB2011). It also has a very nice syntax for function pointers delegates, and also has some syntactic features that are there specifically to support asynchronous message handling.

It's a shame that people only seem to think that it's suitable for Gnome, probably because it grew out of GObject and is part of the Gnome project. It's not! It's a general-purpose language, that just happens to also provide GTK and Gnome bindings as part of its standard library. But it's also compiled, C-compatible (and therefore C++-compatible), and doesn't require a ridiculously large and fragile runtime library.

Maybe someday I'll have an opportunity to actually do a project with it. For now I just feel like I keep on staring through the window at the shiny toy that I wish I could use.

As an attempt at getting rid of some stupid spammers who are also trying to exploit nonexistent scripts on my site, I'm trying to redirect all requests that contain /../ in the original request URI (which are basically guaranteed to be an exploit attempt) elsewhere. However, it looks like mod_rewrite is only performing the substitution rule on the resolved path (i.e. it's treating /foo/../bar/ as /bar/) despite the fact that the REQUEST_URI environment variable still has the original /../-containing expression in it. I know my regexp is written correctly because the rule is working on other things (such as QUERY_STRING and HTTP_REFERER).

So, does anyone know if there's any configurations to mod_rewrite which might fix this behavior?

It's not a big deal but I've noticed a high correlation between the spammers who get through and the folks who are trying to find stupid CGI exploits and I figure anything that trips them up can only help.

In C++ you can mark a method as being abstract pretty trivially, e.g.:

class A {
  virtual foo() = 0;
};

which makes it so that you can't instantiate anything that derives from A until the method foo has an implementation. This is a very useful pattern.

What it's missing, however, is a way of insisting that every instantiable instance of A must provide its own implementation of foo; for example:

class A {
  virtual foo() = 0;
};

class B: public A {
  virtual foo() {}
};

class C: public B {
};

It would be nice if in this case, there were a way to make it so you can't instance C until it gets its own implementation of foo.

Of course, the situation I've run into where this would be exceptionally useful (having a complex DOM which needs per-class script bindings) is kind of nichey, and I can't really see it adding much value to the language as a whole. Still, I can dream...

Recently I'd been messing around with my research 3D engine for various reasons (mostly of nostalgia), and I came to realize that even now there are several things I had been doing with geometry images that still don't appear to be well-known for them. So, I'd might as well write some of it up.

width: Specifies the width of the image. All implementations support images that are at least 64 pixels wide.

A hash table is not using a hash function to distill a key into a value which is used to order it in an associative array/sorted list/etc.

A hash table is using a hash function to distill a key into a value which is used to index into a linear, non-sparse array.

What else should I put into SVN? SOLACE maybe? (Cleaning that up for release would take a lot of work though, and it's not really that useful anymore, except as a general reference on how to do things with geometry images...)

Meaning they've ported an XMMS plugin to XMMS.

I would have preferred if they'd just submitted a patch to make it compatible with XMMS2 so it could be part of the core AudioCompress distribution, but whatever...

8/11 03:15 This has inspired me to go through the code and basically rewrite it. It's amazing how something I wrote as a quick hack as a grad student is still algorithmically-good but of course several years of professional software engineering have given me a completely different perspective on code quality.

But it seemed rather bloated to me, so I rewrote it...

Also, this is the 2⁸th entry. (Yes, I know the archive file isn't numbered 256. But trust me anyway, this is the 256th entry.)

The only reason I'm not releasing it yet is that for some reason, it keeps on blocking on write after 31 fragments are processed. Anyone have any ideas? The patch submitter doesn't have any idea what's going on for me.

Basically, bt let me know about a slight namespace collision between Solace (my ongoing renderer project) and Solace (an online boardgame). Fwee.

Update: The situation has been resolved in a way agreeable to both. If only all trademark issues were so easily dealt with. :)

Concept: Take advantage of underlying UNIXisms to make a file system which has complete, or at least pretty good, undo recovery.