Hello,

I have a problem with transparency while rendering. To make it simple I've made
an example to explain it. The scene consists of 3 cubes of different size,
placed one in another. The problem here is that if I put all the transmit
parameter to 1 with a white background; we should see only a completely white
picture. Here it's not the case, the last cube (the smallest and the one
surrounded by the 2 others) appears black. I don't know if a parameter is
missing in my code,... Here is the code:

#include "colors.inc"
#declare amb = 1;
#declare dif = 0;
#declare ref = 0.001;
camera {
    location <45,45,45>
    look_at 0
    angle 30
  }
  background { color White}

box
    {
      <10,10,10>, <-10,-10,-10>
        texture {
        pigment{color White transmit 1}
        finish { ambient amb diffuse dif reflection ref }
        }
    }

box
    {
      <6,6,6>, <-6,-6,-6>
        texture {
        pigment{color White transmit 1}
        finish { ambient amb diffuse dif reflection ref }
        }
    }

box
    {
      <2,2,2>, <-2,-2,-2>
        texture {
        pigment{color White transmit 1}
        finish { ambient amb diffuse dif reflection ref }
        }

    }
The version I use is the 3.6.
So if someone can help me! :D

Thank you!

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Le 21/04/2012 19:53, JolanYD nous fit lire :
> Hello,
> 
> I have a problem with transparency while rendering. To make it simple I've made
> an example to explain it. The scene consists of 3 cubes of different size,
> placed one in another. The problem here is that if I put all the transmit
> parameter to 1 with a white background; we should see only a completely white
> picture. Here it's not the case, the last cube (the smallest and the one
> surrounded by the 2 others) appears black. I don't know if a parameter is
> missing in my code,... Here is the code:
> 

> So if someone can help me! :D

Have a look at the text output: max trace level by default is 5 and I
guess you reach it.

global_settings{ max_trace_level 20 }

Post a reply to this message

> Hello,
>
> I have a problem with transparency while rendering. To make it simple I've made
> an example to explain it. The scene consists of 3 cubes of different size,
> placed one in another. The problem here is that if I put all the transmit
> parameter to 1 with a white background; we should see only a completely white
> picture. Here it's not the case, the last cube (the smallest and the one
> surrounded by the 2 others) appears black. I don't know if a parameter is
> missing in my code,... Here is the code:
>

3 nested objects means 6 surfaces to compute plus 1 for the background. 
This makes 7 points.
max_trace_level default to 5, so you stop tracing at the 5th surface and 
return black.
Outer box is 2 surfaces plus 1 or 3.
Second box add 2 surfaces for a total of 5, or the default value of 
max_trace_level.
Third box adds 2 more abd gives black.

Solution:
Set max_trace_level to a value large enough to go through all surfaces, 
in your case, that's 7 or larger.
As you have non-zero reflection, there is no other solution.



Alain

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Alain <aze### [at] qwertyorg> wrote:

> > Hello,
> >
> > I have a problem with transparency while rendering. To make it simple I've made
> > an example to explain it. The scene consists of 3 cubes of different size,
> > placed one in another. The problem here is that if I put all the transmit
> > parameter to 1 with a white background; we should see only a completely white
> > picture. Here it's not the case, the last cube (the smallest and the one
> > surrounded by the 2 others) appears black. I don't know if a parameter is
> > missing in my code,... Here is the code:
> >
>
> 3 nested objects means 6 surfaces to compute plus 1 for the background.
> This makes 7 points.
> max_trace_level default to 5, so you stop tracing at the 5th surface and
> return black.
> Outer box is 2 surfaces plus 1 or 3.
> Second box add 2 surfaces for a total of 5, or the default value of
> max_trace_level.
> Third box adds 2 more abd gives black.
>
> Solution:
> Set max_trace_level to a value large enough to go through all surfaces,
> in your case, that's 7 or larger.
> As you have non-zero reflection, there is no other solution.
>
>
>
> Alain

Hello!

Thanks to both of you Alain and Le Forgeron, the solution is perfect!

Good bye!

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