volumetric shader: refraction

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On 08/06/2007 at 05:31, xxxxxxxx wrote:

User Information:
Cinema 4D Version:   10 
Platform:      
Language(s) :     C++  ;

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Hi,

I have similar question to this one, but not in the C.O.F.F.E.E.

I would like to implement refraction to my volumetric shader plugin, but i have no clue how to do this.

In my VolumeData Obiect vd I have obiects like
vd->trans
vd->ray->v
vd->ray->ior
vd->rray->p
vd->rray->ior

but i don't know how to mix them together.

All i need is to implement IOR for refraction.

I'll be apriciate for any help.

Cheers
Bart

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On 08/06/2007 at 08:34, xxxxxxxx wrote:

Generally you need to implement and calculate your own refraction algorithm for volumetric shaders.

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On 08/06/2007 at 08:52, xxxxxxxx wrote:

Even if i only want to change IOR?

Could you give me some clue how to operate on ray vectors?
In SDK there is nothing about it.

And what for i have this:
vd->ray->ior

;) I know that might be sily questions, but simply i don't know how to start.

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On 08/06/2007 at 12:11, xxxxxxxx wrote:

Hi,

vd->ray->ior is the refraction index, but changing this won´t change the transparency ray. So you must modify vd->ray->tray in your volumetric function.

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On 08/06/2007 at 13:46, xxxxxxxx wrote:

hm....

when i want to change alpha channel, all i have to do is:

Vector ret_val = shader->Sample(&cd;);   
vd->alpha = ret_val.x;

and it's work fine

then, when i want to change the bump channel:

ret_bump = shaderBump->SampleBump(&cd;,SAMPLEBUMP_MIPFALLOFF);  
vd->bumpn += (ret_bump*bumpStrength);

and it's work too

but when i want to change transparency, like this:

Vector ret_val = shader->Sample(&cd;);   
vd->trans = ret_val;  
vd->tray->ior = 1.2;

it's wrong.

why this isn't so simple? ;)

how to implement transparency channel?

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On 09/06/2007 at 07:51, xxxxxxxx wrote:

Hey,

anybody ;) please give me some clue how to manipulate transparency and refraction ray. I'm writing master of scient research about ability of makeing volumetric shaders in 3d enviroments like cinema, and all i want to do is to create simple thing (like opaque obiect with parametric index of refraction level - based on volumetric shader) and write sth about it.

i would be appriciate for any example