Alain <kua### [at] videotronca> wrote:

> > Hello everyone!
> >
> > I'm trying to build two cylinders a bit transparent on top of each other (one
> > blue and the other red). Inside theses cylinders, there is a circular arrow
> > (again one blue and the other red). I want the red one to be fully transparent
> > (at the beginning, because the final goal is to make an animation, in which this
> > red arrow will become not transparent).
> > On the rendered picture, we can see a kind of "hole" in the red cylinder that is
> > unwanted. It's like if a part of the red arrow make trouble while rendering and
> > the transparency of the red cylinder is not uniform.
> >
> > Here is the code:
> >
> > #include "colors.inc"
> Don't include those as you don't use the textures they define.
> > //#include "glass.inc"
> > //#include "textures.inc"
> >
> >
> > #declare epaisseurBL = 6;
> > #declare epaisseurIL = 6;
> > #declare epaisseurTL = 16;
> > #declare linethk =0.1;
> >
> > #declare camy=145;
> > #declare camz=170;
> > #declare offsettxt=50;
> >
> > #declare vuex= atan2(camy,camz)*180/pi;
> > #declare vuey= atan2(camz,offsettxt)*180/pi;
> >
> > camera {
> >    location<0,0,0>
> >    look_at <0,0,-1>
> >    rotate<-2,0,0>
> >    translate <-18,(epaisseurBL+epaisseurIL+epaisseurTL)/2, 200>
> >    rotate <-vuex,0,0>
> >    angle 30
> > }
> >
> >
> > global_settings
> > {
> >    max_trace_level 9
> >
> >
> > }
> >
> > background { color White}
> > light_source {
> >      <0, 10, 30>
> >      color White
> >      fade_distance 60
> >      fade_power 2
> > shadowless
> >
> >    }
> >    light_source {
> >      <0, 10, 30>
> >      color White
> >      fade_distance 60
> >      fade_power 2
> > shadowless
> >    }
> >
> > light_source {
> >      <20, 10, 0>
> >      color White
> >      fade_distance 60
> >      fade_power 2
> > shadowless
> >
> >    }
> >    light_source {
> >      <20, 10, 0>
> >      color White
> >      fade_distance 60
> >      fade_power 2
> > shadowless
> >    }
> >
> > light_source {
> >      <0, 50, 0>
> >      color White
> >      fade_distance 60
> >      fade_power 2
> > shadowless
> >
> >   }
> >    // vert <0.2,1,0>
> > #declare couleur1 = Blue;
> > #declare amb = 0.4;
> > #declare couleur2 = Red;
> > #declare transmission = 0;
> > #declare trans1 = 0;
> > #declare trans2 = 0;
> > #declare dif = 0.3;
> > #declare ref = 0;
> > #declare ang = 70;
> >
> > #declare refcyl = 0;
> >
> > #declare epaisseurBL = 10;
> > #declare epaisseurIL = 4;
> > #declare epaisseurTL = 10;
> >
> > #declare FlecheCirculaire = merge{
> >    difference{
> >
> >    cylinder {
> >      <0, -1, 0>,     // Center of one end
> >      <0, 1, 0>,     // Center of other end
> >      25            // Radius
> >
> >    }
> Useless merge
> >    //merge{
> >      cylinder {
> >        <0, -3, 0>,     // Center of one end
> >        <0, 3, 0>,     // Center of other end
> >        20            // Radius
> >
> >      }
> >      prism {
> >        linear_spline
> >        -2, // sweep the following shape from here ...
> >        2, // ... up through here
> >        3, // the number of points making up the shape ...
> >        < 0, 0>, // point#1
> >        <  tan(ang/2*pi/180)*50,50>, // point#2
> >        < - tan(ang/2*pi/180)*50, 50> // point#3
> >
> >      }
> >    //}
> >
> > }
> > prism {
> >      linear_spline
> >      -1, // sweep the following shape from here ...
> >      1, // ... up through here
> >      3, // the number of points making up the shape ...
> >      < -4, 0>, // point#1
> >      < 4,0>, // point#2
> >      < 0,7> // point#3
> >
> >      rotate<0,90-ang/2,0>
> >      translate<-sin(ang/2*pi/180)*22.5,0,cos(ang/2*pi/180)*22.5>
> > }
> > cylinder {
> >        <0, -1, 0>,     // Center of one end
> >        <0, 1, 0>,     // Center of other end
> >        2            // Radius
> >
> > }
> > }
> >
> >
> >
> > #declare MTJ =
> >      merge {
> >        object { FlecheCirculaire
> >          scale <0.8,0.65,0.8>
> >          texture {
> >          pigment{color couleur1 transmit transmission}
> >          finish { ambient amb diffuse dif reflection ref }
> >          }
> >          translate <trans1,0,0>
> >          translate <0,epaisseurBL/2,0>
> >        }
> >
> >        object { FlecheCirculaire
> >          scale <0.8,0.65,0.8>
> >          texture {
> >          pigment{color couleur2 transmit transmission+1}
> Change this line like this:
> pigment{color couleur2 transmit 1 -transmission}
> Otherwise, you get a transmission value larger than 1 whitch gives
> strange results.
>
> >          finish { ambient amb diffuse dif reflection ref }
> >          }
> >          translate <trans2,0,0>
> >          translate <0,epaisseurBL+epaisseurIL+epaisseurTL/2,0>
> >        }
> >      }
> > object { MTJ scale <1,1,1>}
> >
> >
> > //Blue layer
> >
> > #declare layer1=
> >
> > cylinder {
> >        <0, 0, 0>,     // Center of one end
> >        <0,epaisseurBL, 0>,     // Center of other end
> >        30            // Radius
> >        texture {
> >          pigment{color couleur1 transmit 0.7}
> >          finish { ambient amb diffuse dif reflection ref }
> >        }
> > }
> >
> >
> >
> > //Insulator layer
> > #declare layer2=
> Changes to prevent coincident surfaces...
> > cylinder {
> >        <0, epaisseurBL, 0>,     // Center of one end
> <0, epaisseurBL+0.00001, 0>,
> >        <0, epaisseurBL+epaisseurIL, 0>,     // Center of other end
> <0, epaisseurBL+epaisseurIL-0.00001, 0>,
> >        30            // Radius
> >        texture {
> >          pigment{color White transmit 1}
> >          finish { ambient amb diffuse dif reflection ref }
> >        }
> > }
> >
> >
> >
> > //Red layer
> >
> > #declare layer3=
> > cylinder {
> >        <0, epaisseurBL+epaisseurIL, 0>,     // Center of one end
> >        <0, epaisseurBL+epaisseurIL+epaisseurTL, 0>,     // Center of other end
> >        30            // Radius
> >        texture {
> >          pigment{color couleur2 transmit 0.7}
> >          finish { ambient amb diffuse dif reflection ref }
> >        }
> > }
> >
> Your problem is here.
> > object{layer1}
> > object{layer2}
> > object{layer3}
> >
> You have coincident surfaces.
> Redefine your layer objects so that they never overlap and have a very
> small gap between them.
> Another solution would be to translate layer 1 slightly up and layer3
> slightly down.
>
> >
> >
> >
> >
> >
> > If you want to see the red arrow, change the transmit parameter line 159.
> > I use those rendering parameter in my .ini file:
> >
> > Width=1024
> > Height=768
> > Antialias=On
> > Sampling_Method=2
> > Antialias_Threshold=0.01
> > Antialias_Depth=4
> >
> >
> > I tried to change the max_trace_level up to 50, increase the Antialias Depth
> > until 7 and Antialias_Threshold down to 0.001 without success.
> >
> > I use the 3.6 version of POV-ray.
> >
> > If you have any idea to solve this problem tell me!
> >
> > JO
> >
> >
> >
> >
> >
> >

Hello,

thanks for your reply. I've corrected my code with your advices and it works
well! I already know a bit about this coincident surface problem but I forgot to
check it on my code, and that was the problem! Thanks a lot!

Regards,

Yvan

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