art with code

2009-05-24

GLSL parser work-in-progress git repo

To give meself a swift kick in the arse, here the github page.

The grammar is very unfinished and there are probably bad bits involved. The grammar structure comes pretty much directly from the GLSL 1.20 spec, which is nice, as it's LR.

You might notice that it doesn't deal with preprocessor directives, I hope there's a cpp lib out there somewhere. And it's in OCaml so no one can use it for anything.

I'm rather not appreciating the looming mountain of imagined work associated with validating and normalizing GLSL. I mean, syntactical validation isn't going to cut it (though it does help turning "float foo[5] = float[5](0.0, 1.0, 2.0, 3.0, 4.0);" into something that doesn't hit driver bugs.)

GLSL doesn't have numeric literal type coercion, so 20 + 2.2 is a type error. But the Nvidia driver (when you omit the #version pragma) mixes Cg stuff into GLSL, so 20 + 2.2 works there. On ATI it doesn't. On Nvidia with a #version pragma it doesn't work either. So I guess I'll make the pretty-printer add #version 120 at the top of the shader?

And then you have stuff like typecasting vectors, mix() with boolean alpha (IIRC needs #version 130 on ATI, works on Nvidia #version 120), operator overloading and swizzle assignment.

Oh well, it's just work. Do a little bit every day until the day you stop.

Revising initial schedule of "by July 1st" to "by 2012". O, the morning clouds are pretty, 4 am best time of day.
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Built art installations, web sites, graphics libraries, web browsers, mobile apps, desktop apps, media player themes, many nutty prototypes, much bad code, much bad art.

Have freelanced for Verizon, Google, Mozilla, Warner Bros, Sony Pictures, Yahoo!, Microsoft, Valve Software, TDK Electronics.

Ex-Chrome Developer Relations.