POV-Ray : Newsgroups : povray.binaries.images : A head full of hair : Re: A head full of hair Server Time
26 Nov 2022 21:12:17 EST (-0500)
  Re: A head full of hair  
From: Samuel B 
Date: 23 Sep 2021 18:05:00
Message: <web.614cf9b5467a8aa7cb705ca46e741498@news.povray.org>
Thomas de Groot <tho### [at] degrootorg> wrote:
> Op 22/09/2021 om 02:47 schreef Samuel B.:
> > Hey, a fellow i5 owner :) I've got a 6500 here. It's a really good chip.
> >
> <grin> I have an i5 8250 and an i7 8750 here. For some arcane and
> absolutely trivial reasons, I am using the i5 more than the i7, but
> there it is. :-)

Based on user benchmarks, the i5-6500 seems to perform a bit better than the
i5-8250(U), but the i7-8750(H) outperforms both. (The number of cores, however,
do factor into all this.)

From what I've seen, CPU performance has been rather incremental over the years
when it comes to the hard stuff like raytracing... Certain things will always be
slow to parse and/or render, which is why I try to find faster ways of doing
things when possible...

> > Ten minutes of parsing seems a little steep.(...) Thirty minutes of
> > render time doesn't seem as terrible as it could be
> >
> Not sure as I have not been monitoring closely what is going on, I guess
> it is the building of the individual mesh2 hairs which sums up. In a
> next run , I shall save/read the hair meshes and that goes faster in the
> end imo.

What's the shape of the hair follicles? If they are round, how many sides do
they have?

And if you're using includes, then perhaps they are the reason for your high
parse times. So if it's at all possible, maybe try copying all the necessary
macros &/ functions into your scene file, since using includes in any heavy way
is much slower than referencing local code. (But I think you knew this already.)

> But, not trivial, I had the laptop battery in "best battery
> life" mode; "best performance" mode is certainly faster indeed.

I've got a 2012 laptop, and I've been using it without its battery for a number
of years now. (The battery's fine, but I like to extend its life by not using it
;D) The laptop just stays plugged in with high performance mode enabled at all
times. Enabling best/high performance really does make a difference.

An unfortunate thing happened recently... I've got the laptop perched on two
small planks (for air flow) on top of my desktop computer. It's up high so that
the laptop can get a better signal. Well, one night I was a little careless and
didn't notice the planks were slipping... Anyway, the laptop fell off and I put
it back thinking nothing of it. But the next day I realized the earbuds jack was
askew... Turns out the port got bent when everything fell over, and now it only
transmits a signal through one channel D: And I can't observe the contacts
without taking the whole thing apart (I've opened the laptop plenty of times,
but never removed /everything/). My only other option is cutting a hole through
the plastic over the problematic area. but at least the thing is still
functional in all other respects :P

> > Did I ever post my experiments with hair? I was using an .obj-to-.pov converter
> > and trying to grow hair from a mesh. The way I had it set up was if a triangle
> > was too small it only had a small chance to grow a hair, otherwise it would try
> > to grow a certain number of hairs for a given triangle's area. (...)
> >
> I don't remember, but that looks interesting, especially the approach
> using triangle sizes. I had not thought of that aspect. I simply used a
> simple trace() function on the skullcap from randomly generated points
> on an external sphere. Pretty fast by itself.

The code for the hair still exists somewhere, but it is not readily available. I
do, however, have at hand the program I wrote to convert .obj files to
POV-readable data. (I may have posted it once; I'll have to check.) The program
exports arrays, with options for additional data such as neighboring faces and
vertices. (If you remember some preliminary stuff I posted a while back for an
IRTC competition, that's what I was using to make flagstones/stone walls out of
blobs.)

> > P.S. Thanks for reminding me of Wallace and Gromit. It's a great series. Just
> > watched A Close Shave. What a gem of a flick :D
> >
> Oh yes, I love them. I was reminded of the scene showing Wallace tasting
> a piece of Moon (on toast) and musing: "Wensleydale?"

Lol. Based on how often he mentions that particular cheese, I'd say it's his
favorite :)

After you originally mentioned W&G I got to thinking... There might have a way
to make a convincing clay material, complete with fingerprints. It involves the
use of slope patterns and projected normals...

Sam


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