clipka <ano### [at] anonymousorg> wrote:

> One common group of mistakes when trying to model metals (and one which
> I suspect you fell for) is to use non-zero `diffuse` and/or `emission`
> (or `ambient` in older scenes) in the finish.

I started off with the "stock" metals in textures.inc, and yes, they had ambient
and diffuse values.   I just commented those out.   I ought to do that with all
of the textures there, and probably revamp the whole thing, given all we've
learned about good metal textures over the last 15 years or so.


> In metals however, light /never/ enters the material itself.

Well, Feynman's lectures on QED make me question everything I've ever "learned"
about light, but that's material for a WHOLE 'nother discussion.


> However, the main factor is the careless use of `difference`. For
> instance, a heat sink modeled as a union of a base and 11x11 = 121
> individual "fingers" renders about 10 times as fast as a heat sink
> modeled as a single block with 2x10 = 20 "grooves" cut into it.
>
> As a rule of thumb, avoid `difference` wherever possible.

Really???   My heatsinks are ALL primarily made with loops of differences.  I
try to avoid them, after reading Mike Williams' page about holes, but they are
convenient.   It must be something else slowing down that scene.

I'm making NINE heatsinks, and that's only one.

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