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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