Thursday, September 20, 2007

Flat Shading is Evil (and other OBJ sins)

Almost two years ago, I posted this blog entry, pointing out that some legacy OBJ commands are, well, evil.

My inclusion of ATTR_poly_os in that blog post was a little strange - when used correctly, ATTR_poly_os is the right way to overlay decals on the ground, and it is fully supported. (The message is just, I suppose, that if you need a huge number for your poly_os, something is really wrong.)

Now ignoring ATTR_poly_os, you might notice that the AC3D plugin exports almost none of those dubious attributes. But what about flat shading? Flat shading isn't necessary, but you were allowed to use it.

So I came to my senses and modified the AC3D exporter - the exporter will now never use ATTR_shade_flat - instead it uses smooth shading and per-vertex normals, avoiding an unnecessary attribute no matter what you do in AC3D. 99.99% of the time this will yield fastest framerate?

Why wasn't the plugin always like this? I thought it was, and only discovered today that I hadn't finished this optimization.

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