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Zeger Knaepen wrote:
> pigment {
> camera_view{[mask-scene camera settings]}
> pigment_map {
> [0 rgbt 1]
> [1 camera_view{[original camera settings]}
> }
> }
This does not create the correct gradient. I'll demonstrate with a simpler
gradient:
// Incorrect:
color_map {
[0, red 1]
[1, rgbt 1]
}
// Correct:
color_map {
[0, red 1]
[1, red 1 transmit 1]
}
The former incorrectly gives rgb <1.0,0.5,0.5> transmit 0.5 halfway through.
That's a semi-transparent pink, not a semi-transparent red.
The latter correctly gives rgb <1,0,0> transmit 0.5 halfway through.
Likewise, if you want to create a patterned blend between some MyPigment and
a transparent pigment, then you must use for the transparent pigment a
pigment identical to MyPigment, except that all transmit values are 1. Yes,
it's cumbersome.
However, in the particular situation we're dealing with, there is a
workaround. Some image manipulation software, like Photoshop, Paint Shop
Pro, and probably The Gimp, has a feature to remove a matte. Basically, if
you open the image created using your proposed method and then use the
feature "Remove white matte", then the incorrect effect of using a
transparent pigment that's white will be removed.
Rune
--
http://runevision.com
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