Saimazoom nous apporta ses lumieres en ce 19/11/2006 11:59:
> Hi

>  I'm not really new to POVRAY, but it is a log time since the last time I
> used it(1.x) and it seems that I forgot something important, because I
> cannot make this simple scene to work.

>  In the scene I have a plane, and on top of the plane a pyramid with a
> parallel light hitting one of the faces. I've added a translucent plane on
> top of everything just to watch the reflection of the light in the side of
> the pyramid going trought this second plane. But there is no reflection at
> all.

>  The code is as follows:

> ---------------------------------------------
> #version 3.6

> #include "colors.inc"

> #declare Photons=on;

> global_settings {
>   assumed_gamma 1.0
>   //radiosity {brightness 0.3}
>   max_trace_level 5
>   #if (Photons)          // global photon block
>     photons {
>       spacing 0.01                 // specify the density of photons
>       //count 100000               // alternatively use a total number of
> photons
>       //gather min, max            // amount of photons gathered during
> render [20, 100]
>       //media max_steps [,factor]  // media photons
>       //jitter 1.0                 // jitter phor photon rays
>       //max_trace_level 5          // optional separate max_trace_level
>       //adc_bailout 1/255          // see global adc_bailout
>       //save_file "filename"       // save photons to file
>       //load_file "filename"       // load photons from file
>       //autostop 0                 // photon autostop option
>       //radius 10                  // manually specified search radius
>       // (---Adaptive Search Radius---)
>       //steps 1
>       //expand_thresholds 0.2, 40
>     }

>   #end
> }

> // ------------------------------------------------------------

> // ... Parallel source light ...
> light_source {
>   <5,20,0>       // light's position
>   color White      // light's color
>   cylinder
>   radius 20
>   parallel
>   point_at <5, 0, 0>      // direction of spotlight
>   area_light <1, 0, 0>, <0, 0, 1>, 2, 2
>   adaptive 1
Adaptive don't have any effect on a 2*2 area_light. adaptive 1 don't have any 
effect unless your aray is at least 4*4, use 5*5, 9*9, 17*17 or more for best 
efficiency. A power of 2 + 1.
>   jitter
>   tightness 1            // tightness of falloff (1...100) lower is softer,
> higher is tighter
>   falloff 1               // intensity falloff radius (outer, in degrees)
>   photons {           // photon block for a light source
>     refraction on
>     reflection on
>   }
> }


> // ------------------------------------------------------------

> //--------------------------------------------------------- Pyramid_N macro
> #macro Pyramid_N (N, Radius1, Radius2, Height)
> //-------------------------------------------------------------------------
> #local D= 0.00001;

> intersection{
>  #local Nr = 0;    // start
>  #local EndNr = N; // end
>  #while (Nr < EndNr)

>   // linear prism in z-direction:
>   prism { -2.00 ,2.00 , 5 // from z1, to z2 , number of points (first =
> last)
>          <-2.00, 0.00>, < 1.00,  0.00>,
>          < 0.00+Radius2/Radius1,1.00>,
>          <-2.00,1.00>, <-2.00, 0.00>
>          rotate<-90,0,0> scale<1,1,-1> //turns prism in z direction!
>          scale <Radius1+Nr*D,Height+Nr*D,Radius1+Nr*D>
>          rotate<0,Nr * 360/EndNr,0>
>      } // end of prism ----------------------------------------------------

>  #local Nr = Nr + 1;    // next Nr
>  #end // ----------------  end of loop
> } // end of intersection

> #end // ------------------------------------------------------ end of macro


> // ------------------------------------------------------------


> camera {

>   location  <0,50,0>
>   look_at   <0,0,0>
> }


> plane {
>   y, 1

>  texture {
>     pigment { color rgb <1, 1, 1> }
>   }
>   photons {
>   reflection on
>   refraction on
>   }
> }


> plane {
>   y, 20
>  texture {
>     pigment { color rgbt <0, 1, 0, 0.8> }
>   }
>   photons {
>   reflection on
>   refraction on
>   }
> }

> object {
>     #Pyramid_N (4,10,0,5)
>     translate <0 1 0>
>     texture {
>         pigment { color Blue }
>     }
>     finish {
>     reflection { 0.5 }
>     }

>     photons
>     {
>     reflection on
>     refraction on
>     }
> }


> -----------------------------------------------------------------------

You need phong or specular in the finish, or have a look_like in the light's 
deffinition. As light_source are only abstractions, dimentionless point, from 
where light come, and not objects, they never show in reflections.
The lighter spot on the pyramid is just the spot where your cylinder light hits 
the surface, shown by rotating the pyramid. Changing the falloff will change 
it's dimention.

-- 
Alain
-------------------------------------------------
Bet my floppy's bigger than yours.

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