Ex Nihilo

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OpenGL Quirks

I’ve started light by simply merging some of the sketches from last month’s workshop. That has mainly meant translating 2D demos to 3D space so far, and I’m already running into some interesting OpenGL quirks.

3D Radial Demo

This applet (requires Java Virtual Machine) for instance; there’s a clear dividing line between the left and right half; the lines are darker on the left, lighter on the right. This is true no matter whether I use the lights() function or not. No idea what’s causing it.

And 3D shapes appear to be slow as molasses. Admittedly I’m on a MacBook Pro with only a mid-range graphics card, but I’d expect better results than this. Here’s a basic 25 sphere “starfield”, it renders pretty smoothly:


But bump it up to 125 and look out:


Keep in mind the previous applet draws about 5000 2D lines per cycle, vs. the 125 spheres in the last video, so 2D shapes are clearly a lot less taxing than 3D shapes. But 125 shapes is barely scratching the surface of what I imagined Processing could accomplish, so I’m clearly missing something.

What do the pros do? I’m guessing the choice is to either ignore framerate and render to a sped up movie, or fake 3D with 2D objects. I’ll have to keep digging into this one. Update: aha, buffering.

(and actually, now that I’m looking at the movies again, I’m wrong — those aren’t even spheres, they’re just ellipses. No idea why this example’s so bad; I can normally get a few thousand ellipses moving pretty quickly, I guess this is just a crappy example. The point remains when applied to spheres though.)

Wednesday, July 22nd, 2009 | 3D | RSS 2.0

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