Alan Kong wrote:

> On Thu, 22 Jun 2000 18:32:39 -0700 SamuelT <STB### [at] aolcom> wrote:
>
> >What do you think? Is the grass fast?
>
> What do you think? Is the grass fast?
> Samuel's clouds do cast
> shadows upon his sea of grass, so vast,
> until such time when clouds have passed
> reminding us that forever nothing will last.

It was a valid question. I really don't know if it is fast for grass or
not. It's the fastest I've been able to get grass to render, but perhaps
there are faster ways?


>   Okay, I'm not a poet. How about the source for your grass scene,
> Samuel?

I will, one I get it to look more like grass, and less like green bird
feathers :) Plus, the code is at home, and I am at work right now....

~Sam

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I've got to remember how to animate, but my computer currently crashes when I try
to play an avi file.

Bob Hughes wrote:

> "SamuelT" <STB### [at] aolcom> wrote in message news:3952BE36.8E44BAC1@aol.com...
> | Here's some fast-rendering grass I came up with today.  The whole scene
> | (5000 blades of grass, 25001 objects) took only 1 minute, 57 seconds
> | with aa on. I'm running an AMD k6-2 500 mhz processor with 128mb ram.
> | What do you think? Is the grass fast?
> |
> | P.S. I rotated and scale the grass according to a hidden pigment to
> | simulate wind effects.
>
> It's fast if that's render + parse time, I think so anyhow.
> I realize now that it isn't just made up of a zero-sided box and a single
> triangle as I first thought, silly me.  But I still don't understand anything
> about eval_pigment yet.  I'll get around to it someday though.
> If you have this ready to animate (or not) I'm sure it would look fantastic if
> it were.
>
> Bob

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"Tony[B]" wrote:

> Interesting... I've never seen little stalks like that at the bottom of
> grass. Looks good for a far off effect, on hills and stuff.

Me neither. I was trying to make the tall kind of grass, but as I mentioned to
Alan, it looks like bird feathers instead.

~Sam

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Christoph Hormann wrote:

> Thats's pretty fast, BTW, you are using the same computer as me :-)

The same computer, really? I bet mine crashes more though...


> A little variation in blade bending would be nice, even though that
> would probably destroy the efficiency...

Yes, it would render a lot slower if I did that, unless I used scale z*n to
do it.... hmmm......


> IMO it would also be a good idea adding that eval_pigment construction
> to other similar macros.
>
> Christoph

It would be great if someone could figure out how to use it for trees.

~Sam

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In article <3952db8e@news.povray.org>, "Bob Hughes" 
<per### [at] aolcom?subject=PoV-News:> wrote:

> But I still don't understand anything about eval_pigment yet.

It is quite simple:
A pigment simply defines a color for each point in space, using a color, 
image, or pattern + color_map. The eval_pigment returns the rgb color of 
the pigment at a specified point of space.
Since a color is basically a vector, you can use this to pattern 
interesting displacements like wind-blown grass, rock placement in a 
stream, smoke particles, etc...you can get much more variation and 
control than you would get with just turbulence.

-- 
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://chrishuff.dhs.org/
TAG Web page: http://tag.povray.org/

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In article <39539F62.51B7B1C8@aol.com>, STB### [at] aolcom wrote:

> I've got to remember how to animate,

Try adjusting phase while translating the pigment...maybe add some 
turbulence to the pigment too.

-- 
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://chrishuff.dhs.org/
TAG Web page: http://tag.povray.org/

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In article <3953A064.3E966CF9@aol.com>, STB### [at] aolcom wrote:

> It would be great if someone could figure out how to use it for trees.

You could use eval_pattern() or eval_pigment() to control the branch 
number and probability according to a pattern...and you could have 
recursion stop when one goes below a certain threshold. Could make some 
interesting topiary.

-- 
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://chrishuff.dhs.org/
TAG Web page: http://tag.povray.org/

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He forgot to mention it doesn't test for all colors in a scene, it tests
for a pigment you feed it. By the, Chris, how would use use eval_pigment
for smoke?

~Sam


Chris Huff wrote:

> In article <3952db8e@news.povray.org>, "Bob Hughes"
> <per### [at] aolcom?subject=PoV-News:> wrote:
>
> > But I still don't understand anything about eval_pigment yet.
>
> It is quite simple:
> A pigment simply defines a color for each point in space, using a color,
> image, or pattern + color_map. The eval_pigment returns the rgb color of
> the pigment at a specified point of space.
> Since a color is basically a vector, you can use this to pattern
> interesting displacements like wind-blown grass, rock placement in a
> stream, smoke particles, etc...you can get much more variation and
> control than you would get with just turbulence.
>
> --
> Christopher James Huff - Personal e-mail: chr### [at] maccom
> TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
> Personal Web page: http://chrishuff.dhs.org/
> TAG Web page: http://tag.povray.org/

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In article <3953AFFF.6F9A4753@aol.com>, STB### [at] aolcom wrote:

> He forgot to mention it doesn't test for all colors in a scene, it tests
> for a pigment you feed it. By the, Chris, how would use use eval_pigment
> for smoke?

With smoke, it could be used to make a "swirly" effect depending on a 
pattern, or you could just use it to turbulate the particles a bit. Or 
you could use it as "wind", and fake the wind currents near objects and 
the ground.

-- 
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://chrishuff.dhs.org/
TAG Web page: http://tag.povray.org/

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Hmm, sounds interesting. Might have to try that sometime.

~Sam


Chris Huff wrote:

> In article <3953AFFF.6F9A4753@aol.com>, STB### [at] aolcom wrote:
>
> > He forgot to mention it doesn't test for all colors in a scene, it tests
> > for a pigment you feed it. By the, Chris, how would use use eval_pigment
> > for smoke?
>
> With smoke, it could be used to make a "swirly" effect depending on a
> pattern, or you could just use it to turbulate the particles a bit. Or
> you could use it as "wind", and fake the wind currents near objects and
> the ground.
>
> --
> Christopher James Huff - Personal e-mail: chr### [at] maccom
> TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
> Personal Web page: http://chrishuff.dhs.org/
> TAG Web page: http://tag.povray.org/

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