Rune wrote:
> 
> Could someone who knows the inner workings of POV-Ray (and MegaPOV) please
> tell me why transmit values outside the range of 0 to 1 work as they do?
> 
> And why does it work differently in MegaPOV than in POV-Ray 3.1?
> 
> In povray.binaries.images I have posted some graphs that show how the
> transmit value seem to work in POV-Ray 3.1, in MegaPOV 0.6, and how I would
> like it to work.
> 
> The reason I would like the transmit value to work different is that if it
> works my way (which is more simple), it can be used for many different
> special-effects such as inverting pigments and contrast-enhancing pigments.
> 
> My suggested change will most probably not brake any old scenes because it's
> not very common to use transmit values outside the range of 0 to 1. Values
> between 0 and 1 will work the same way as it currently does.
> 
> I have brought up this subject before, but not got the response I hoped for.
> This time I *really* hope for some feedback - especially from people who
> know what they're talking about! ;)
> 
> If you don't want to use my suggested change, could you at least tell me
> *why* it should work as it currently does?
> 
> Rune

So you're saying that the colour should be simply (1-t)*pigment +
t*background ?
Sounds good to me.  I've used strange transmit values to modify the
background colour but in that case I usually use rgbt of
<0,0,0,SomeOddValue> so the change would not affect me.
BTW I don't know why MP clamps negative values to zero.

PoD.

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