On 10/11/2018 04:20, And wrote:

On 11/11/2018 08:43, Le_Forgeron wrote:
>> I want this function, too. But I want it for UV map...
>>
>>
> UV mapping of object does make sense (in term of trace), but I'm still
> perplex about getting the colour...
> 
> There could be more than a single texture (layered), or a complex
> texture, and there is finish too which can interfere (a white pigment
> with a mirror finish reflecting a complex environment).
> 
> So, when asking for "colour" at intersection point, what is expected ?
> #1: the colour (<r,g,b>) of the point as it would appear on a rendered
> image (e.g. a white sphere in the dark would return black)
> #2: the intrinsect colour(<r,g,b>) of the object at that point (e.g. a
> white sphere in the dark would return white)
> 

I’ve thought about this in the past.
I think that your option #1 is too complicated. It seems to me that it 
would involve a secondary raytracing operation with maybe a limit to the 
depth of reflective and/or refractive bounces. (Sorry, I don’t have the 
right vocabulary.)
Option #2 is closer to what I would find useful. If “trace” also 
returned the RGB* value of the uv image map at the point of intersection 
of the object by trace. That would be usable.
* Also filter and transmit values, if possible.


> (Yes, I'm repeating C.Lipka's question, because it went unanswered)

Your option #2 opens up the discussion. Christoph's answer on first 
reading is too similar to what every other reply to this question has 
been. Which is: No, nay, never.


-- 

Regards
     Stephen

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