anidonu nous apporta ses lumieres en ce 05/07/2006 15:24:
> It's straightforward to model a light source  with a lens to form a real
> image.  But is it possible to form an image of a diffuse object?
> Comments are welcome on why this file does not do so.
> 
> /*  Makes a photon mapping scene with single or crossed cylindrical lenses
> 
>     The lens is formed from the intersection of a glass cylinder height
> 2*HCyl along the y-axis, with a plane parallel to its axis.
>     The radius of the cylinder is RCyl.
>     The refractive index of the glass is RefIndx
>     The intersecting plane, parallel to the xy plane, is SCyl
>     The lens stands on its end on a checkered plane
>     A square array of distant lightsources is imaged by the lens to a focus
> screen
>     The screen position is animated
>     A transparent 'slide' is in front of the lights array
> */
> 
> #include "colors.inc" #include "textures.inc"
> 
> global_settings {  assumed_gamma 2.2       max_trace_level 32
>                    photons { count 1500000 max_trace_level 32 }
>                 }
> 
> #declare k = 0.5; //clock;
> 
>
/*********************************************************************************************************/
> 
> /* Choose a single lens or a crossed pair in contact */
> #declare Crossed = no;
> #declare Crossed = yes;
> 
>
/********************************************************************************************************/
> /*Specify the lens setup*/
> 
> #declare RCyl = 200;
> #declare SCyl = 192;
> #declare RefIndx = 1.517;
> #declare CapHght = RCyl - SCyl;
> #declare HCyl = sqrt(RCyl*RCyl - SCyl*SCyl );
> 
> 
> #declare PlanoCyl = intersection { cylinder { -y*HCyl, y*HCyl,RCyl}
>                                    plane { z,SCyl inverse }
>                                    material { texture { pigment { rgbt
> <0.9,0.98,0.9,0.98> }
>                                                         finish { ambient
> 0.02 diffuse 0.008 reflection 0.01 } }
>                                               interior { ior RefIndx }
>                                             }
>                                  }
> 
> #declare BFL = RCyl/(RefIndx-1);
> 
> /************************* Setup the focus screen and a baffle */
> 
> #declare Screen = box { <-1,-1,0>,<1,1,0.1> scale 50 pigment { rgb 1 }
> finish { ambient 0.02 diffuse 0.8} }
> #declare ScrnPos = -z*(BFL+ 50*(2*k-1));
> 
> #declare Stop = intersection { box { <-200,-200,0>,<200,200,1> }
>                                box { <-HCyl,-HCyl,-1>,<HCyl,HCyl,2> inverse
> }
>                                pigment { rgb 1 } finish { ambient 0 diffuse
> 0 reflection 0 }
>                              }
Beter to use difference than intersection and inverse, it's clearer.
> 
> /************************** Photon mapping lightsources
> *******************************/
> 
> #switch ( Crossed)
>   #case( yes) #declare LyteBryte = 0.0003*1e0; #break
>   #case(no)   #declare LyteBryte = 0.003;  #break
> #end
> 
> #declare Step = 2.5e2;
> #declare I = -1e3;
> 
> #declare LiteMatrix = union { #while ( I<=1e3)
>                                  #declare J = -1e3;
>                                  #while ( J<=1e3)
>                                     light_source { <I,J,15000>, color rgb
> LyteBryte
>                                                     photons {refraction on
> reflection on}
>                                                  }
>                                     #declare J = J + Step;
>                                  #end
>                                  #declare I = I + Step;
>                               #end
>                             }
> 
> 
> /**************************   The test object is a partially transparent
> color_map ********************/
> 
> 
> #declare Slide = box { <-1e3,-1e3,0>,<1e3,1e3,1e1>
>                        pigment { gradient x color_map{ [0 rgbt<0,1,0,0.5> ]
>                                                        [1 rgbt<1,0,1,0.5> ]
>                                                      }
>                                   translate -x*0.5
>                                   scale 1e2
>                                }
>                         finish { ambient 0 diffuse 1.0 }
>                      }
> 
> /*******************************  THe scene
> ******************************************/
> 
> 
> // CamNum = 1 for an oblique downward look at scene
> // CamNum = 2 for the camera 150mm infront of and looking at screen
> 
> #declare CamNum = 1;
> #switch ( CamNum )
>   #case(1) #declare CamPos = 1e3; #declare CamAng = 5; #break
>   #case(2) #declare CamPos = ScrnPos+z*150; #declare CamAng = 55; #break
> #end
> 
> 
> 
> #declare Projekta = union { object { PlanoCyl  translate -z*SCyl}
Would be beter to use a merge here to remove internal surfaces.
>                             #if( Crossed = yes) object { PlanoCyl  rotate
> z*90 translate -z*(SCyl+CapHght)} #end
>                             object { LiteMatrix  translate z*15100 }
> 
> 
>                             photons { target }
>                           }
> 
> object { Slide translate z*15000 photons { target } }
> object { Projekta }
This is you lense, it MUST have photons{target refracion on}, otherwize, you don't
shoot any photon 
at it.
> object { Screen   translate ScrnPos  photons { target }}
This the screen on whitch you project the photons, it DON'T need a photons block. You
don't shoot 
photons at it, it collect them and make them visible.
> object { Stop translate z*5}
> 
> background { rgb 0.5 }
> 
> camera { location  CamPos look_at  ScrnPos angle CamAng }
> 
> 
> 
> 
> 
The light_source are to close to the slide: Put them back by about 10 times or make
them parallel.

-- 
Alain
-------------------------------------------------
Beam me up Scotty. This isn't the men's room.

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