Espen <nomail@nomail> wrote:
> Thanx!  Putting in rgbt instead of rgbf worked right away.

  I'm actually not 100% sure about the functions used for the filter
and transmit channels, but as far as I can tell, the filter channel
is a substractive channel while the transmit channel is a kind of
"alpha" channel (in the same way as eg. in a png).

  Substractive means in practice that the color of the surface will
block any light going through it which is not of the color of the
surface. In other words, it will *filter* the light.
  So for example, if the color of the surface is rgbf <1, 1, 0, 1>
then it will let all red and green components pass, but will block
any blue component, and thus no blue light will pass through.
  The values of the filter between 0 and 1 means, AFAIK, how much
of the filtered light is shown and how much of the surface's own color.
In other words, if you had rgbf <1, 1, 0, 0.5> then half of the color
will be from the surface's own color (ie. <1, 1, 0>) and half of it
will be of the light going through (which is filtered by <1, 1, 0>).

  The transmit is basically the same, but it doesn't block anything.
It thus works like an alpha channel. If transmit is 0 then only the
surface color is shown. If transmit is 1, then only the light passing
through is shown. If it's eg. 0.5 then half and half are shown (or in
other words, their average).

-- 
                                                          - Warp

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