Nekar Xenos wrote:
> 
> I wonder how 3d graphics cards do it? I've seen something like tri-linear
> something-or-other gives the best results in games. Don't know exactly how
> it works and if it only works with bitmaps. The top one gives a nice
> 'paintbrush' effect. I would have thought to do something like the Blend
> option in CorelDraw for patterns but that might also be a bit difficult.
> 

3d graphic cards work completely different.  First they only use rastered
2d textures, second they all use scanline rendering techniques.  

BTW, Chris Huff's new blur method in fact does something like 3d rastering
and interpolation, different interpolation methods like linear and cubic
would proably be a useful feature.  

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

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In article <3AA41E45.D73EB34F@rsp.com.au>, Ben Paschke 
<ben### [at] rspcomau> wrote:

> > I don't think there *is* another way to do it. Well, you could probably
> > create a DF3 pattern from an array with the data generated using
> > eval_pattern()...difficult, slow, and memory consuming.
> 
> The only possible way i'd thought of was jittering the positions of 255
> averaged textures. Not that efficient!

And it doesn't do interpolation, so you will still have "stair steps" in 
the output.

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

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In article <3aa492cf@news.povray.org>, "Nekar Xenos" 
<vir### [at] iconcoza> wrote:

> I wonder how 3d graphics cards do it? I've seen something like tri-linear
> something-or-other gives the best results in games. Don't know exactly how
> it works and if it only works with bitmaps. The top one gives a nice
> 'paintbrush' effect. I would have thought to do something like the Blend
> option in CorelDraw for patterns but that might also be a bit difficult.

I think programs that use a graphics card for blurring usually just use 
a lower resolution blurred version of the image map, and render that 
with bilinear or bicubic interpolation turned on, which is similar to 
what my patch does, but 2D. Tri-linear interpolation probably had 
something to do with 3D textures, and is usually more for smoothing out 
texels than blurring.

The main difference is that this patch only handles pattern values, not 
colors, and it only turns small portions of the pattern into voxels at a 
time, so it doesn't have to handle huge amounts of data. (but has to 
recompute a bunch of stuff during rendering)

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

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In article <3AA4BB0D.FA54A566@gmx.de>, Christoph Hormann 
<chr### [at] gmxde> wrote:

> 3d graphic cards work completely different.  First they only use rastered
> 2d textures, second they all use scanline rendering techniques.  

Actually, some are capable of using 3D raster images...


> BTW, Chris Huff's new blur method in fact does something like 3d 
> rastering and interpolation, different interpolation methods like 
> linear and cubic would proably be a useful feature.  

I originally planned that, but I'm not so sure any more...I think I can 
get away with an extension of linear interpolation. That, and sampling 
the created voxels within their area, not just at their centers.

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

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Tony[B] wrote:
> 
> Dang! Quick as usual! That's a very good thing. :)
> 
> Interesting pattern... Um, can you mention at least one case in which we
> would actually need this or it would be hard to do any other way?

I need this all the time.

I often make textures by employing the repeat warp functions, especially
for concrete type walls. This looks good, except for the sudden
transitions between ajacent cells. If this could be smoothed, or
blurred, it would be all the better.

I'm not sure if this is applicable to the technique demonstrated, but I
hope it is. It would also look good with some of the megapov textures,
like the solid crackles.


Simon

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