Hi
I just started learning Pov-Ray. I'm trying to add different shading to my
objects. Is there anyway I can create a Gouraud Shading??

annelize :-)

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annelize wrote:
> 
> Hi
> I just started learning Pov-Ray. I'm trying to add different shading to my
> objects. Is there anyway I can create a Gouraud Shading??

About the closest thing POV-Ray has to Gouraud Shading is smooth triangles
for mesh objects. Otherwise, normal procedural textures should accomplish
the same thing for all other object types that POV-Ray supports.

-- 
Ken Tyler

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"annelize" <ann### [at] tiscalidk> wrote in
news:web.3d702a1d215c86447aca4b930@news.povray.org 

> Hi
> I just started learning Pov-Ray. I'm trying to add different shading
> to my objects. Is there anyway I can create a Gouraud Shading??

btw. what lighting effects for solid surfaces are known ? AFAIK goraud, 
phong, specular (last is the best). 
And in MegaPOV there AFAIR was some other method ?

-- 
#macro g(U,V)(.4*abs(sin(9*sqrt(pow(x-U,2)+pow(y-V,2))))*pow(1-min(1,(sqrt(
pow(x-U,2)+pow(y-V,2))*.3)),2)+.9)#end#macro p(c)#if(c>1)#local l=mod(c,100
);g(2*div(l,10)-8,2*mod(l,10)-8)*p(div(c,100))#else 1#end#end light_source{
y 2}sphere{z*20 9pigment{function{p(26252423)*p(36455644)*p(66656463)}}}//M

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Rafal 'Raf256' Maj wrote:
> 
> > I just started learning Pov-Ray. I'm trying to add different shading
> > to my objects. Is there anyway I can create a Gouraud Shading??
> 
> btw. what lighting effects for solid surfaces are known ? AFAIK goraud,
> phong, specular (last is the best).

That's nonsense, like Ken said gouraud shading is something specific to
mesh rendering, the phong and specular models are methods for generating
highlights - there is no use in comparing techniques for different
purposes concerning quality.

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 13 Aug. 2002 _____./\/^>_*_<^\/\.______

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Wasn't it Rafal 'Raf256' Maj who wrote:
>"annelize" <ann### [at] tiscalidk> wrote in
>news:web.3d702a1d215c86447aca4b930@news.povray.org 
>
>> Hi
>> I just started learning Pov-Ray. I'm trying to add different shading
>> to my objects. Is there anyway I can create a Gouraud Shading??
>
>btw. what lighting effects for solid surfaces are known ? AFAIK goraud, 
>phong, specular (last is the best). 
>And in MegaPOV there AFAIR was some other method ?
>

MegaPOV could use the Torrance-Sparrow-Blinn-Cook microfacet highlight
model (Blinn highlights).

-- 
Mike Williams
Gentleman of Leisure

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annelize <ann### [at] tiscalidk> wrote:
> I just started learning Pov-Ray. I'm trying to add different shading to my
> objects. Is there anyway I can create a Gouraud Shading??

  As it has been noted, Gouraud shading is something exclusive to polygons,
and mainly developed for scanline rendering. The idea is that for scanline
rendering it's cheaper to do Gouraud shading than Phong shading. However,
the results look a lot worse (specially at polygons which should have a
highlight). I don't see any reason for use this lighting model (even, if
you wanted to use it with meshes) because the result is not nice and Phong
works a lot better.

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -

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Rafal 'Raf256' Maj wrote:
> 
> "annelize" <ann### [at] tiscalidk> wrote in
> news:web.3d702a1d215c86447aca4b930@news.povray.org
> 
> > Hi
> > I just started learning Pov-Ray. I'm trying to add different shading
> > to my objects. Is there anyway I can create a Gouraud Shading??
> 
> btw. what lighting effects for solid surfaces are known ? AFAIK goraud,
> phong, specular (last is the best).
> And in MegaPOV there AFAIR was some other method ?
> 
> --
> #macro g(U,V)(.4*abs(sin(9*sqrt(pow(x-U,2)+pow(y-V,2))))*pow(1-min(1,(sqrt(
> pow(x-U,2)+pow(y-V,2))*.3)),2)+.9)#end#macro p(c)#if(c>1)#local l=mod(c,100
> );g(2*div(l,10)-8,2*mod(l,10)-8)*p(div(c,100))#else 1#end#end light_source{
> y 2}sphere{z*20 9pigment{function{p(26252423)*p(36455644)*p(66656463)}}}//M

In the Gouraud model in each vertex of all triangles a normal is
defined. Using this normals the light intensity in the vertices is
determined and the light intensity in each point of a triangle is an
interpolation of the light intensities in the vertices. The Gouraud
model uses an interpolation of LIGHT INTENSITIES.
In the Phong model (smooth triangles) in each vertex of all triangles a
normal is defined. Using this normals the normal in eacht point of a
triangle is an interpolation of the normals in the vertices. The Phong
model (smooth triangles) uses an interpolation of NORMALS. This model is
better adopted to handle reflection, etc...
-- 
Herman Serras
Gent (Belgium)
http://cage.rug.ac.be/~hs/

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