Re: [Yafray-devel] on line updates...

[Alfredo de Greef]

--- Andera <address@hidden> wrote:
> On lun, 2003-01-06 at 02:20, Alejandro Conty Estevez
> wrote:
> > On Fri, Jan 10, 2003 at 08:09:02PM +0100, Andera
> wrote:
> > > Ok, I have posted on Elysiun for the yable
> update....I have uploaded
> > > yable-0.28 and yable-0.29.
> > > I have tested both all the day, they works...
> > > Yable-0.30 is ready too...
> > 
> > :-) as you know yafray 0.0.3 is ready too, only
> your skin loader is
> > missing (will make it tomorrow). I hope my site to
> wake up soon to
> > release it.
> > 
> > Did you add eeshlo's spot light, sky background,
> fog and gamma 
> > correction support?
> Wow!! All this? All in the 0.0.3 :)))
> I guess that my answer is not...yable is not ready!
> Let me know the syntax, I will add these features!!
> Andrea

I didn't tell you about that yet, as I have to wait
until Jandro approves of the changes.

Anyway here is the syntax again with explanations as I
told Jandro:

-----------------------------------------------------

This is an example of a the new sunsky background.

<!-- sunsky background shader -->
<background type="sunsky" name="sky" turbidity="4"
add_sun="on">
        <from x="-7" y="-10" z="1" />
</background>

'tubidity' controls atmosphere density, 4 which is the
default is an almost clear sky, higher values may or
may not work well, since the chromaticity/rgb
conversion is not how it is done in the official code,
which uses an elaborate function based on spectral
data. Atmosphere effects themselves are also not used.
So it only affects the overall color and the sun
effect on the atmosphere.
With 'add_sun' you can specify if an actual sunlight
should be created at the specified position but also
with the correct color at that position in the sky.

This is an example of a render block with all the new
parameters:

<render camera_name="Camera" samples="16" raydepth="5"
        bias="0.001000" tolerance="0.06"
        gamma="1.5" exposure="1.4142136"
        fog_density="0.005" >
        <fog_color r="1" g="1" b="1" />
        <outfile value="myimage.tga"/>
</render>

'gamma' controls the gamma correction, 1.0 is
no correction(default), lower than 1.0 will make the
image darker and also enhance contrast, higher values
will make the image brighter but also has a tendency
to 'compress' the colors which can make the image have
a slightly 'bleached' look. So it is best to not set
it too high.
'exposure' controls any exposure adjustments, if set
to 0, no exposure calculations are done. This
parameter can be used to 'compress' the entire
brightness of the picture in the range 0-1, no matter
how high the actual intensities are. The parameter
controls the brightness curve, the default is sqrt(2),
lower is darker, higher is brighter, but it all
remains in the range 0-1.
'fog_density' controls exactly that, a value of 0
means it is switched off. Use very low values for more
realistic effects, can work well with landscapes, It
is the most simplest implementation however and can be
improved quite a bit, it should also be implemented
differently, not like I did directly in scene.cc, but
also a shader instead, so it can be later expanded to
other types like real volumetric fog for instance.
'fog_color' sets the color used for the fog, this too
should be different, it would probably be better used
with the background color.

And finally, the spotlight:

<light type="spotlight" name="spot" power="100.0"
size="50" blend="20" beam_falloff="2">
        <from x="-7" y="-10" z="6" />
        <to x="0" y="0" z="0" />
        <color r="1" g="1" b="1" />
</light>

I tried to use similar names as in Blender, 'size' is
the width of the lightcone in degrees ('SpotSi' in
Blender), 'blend' is the transition width of the
lightcone, it controls the softness of the edge
('SpotBl' in Blender), and finally 'beam_falloff' is a
parameter to control the light distribution fallof
inside the lightcone, the higher, the softer the light
becomes from bright in the center to darker towards
the edge.

-----------------------------------------------------

Alfredo


__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
http://mailplus.yahoo.com