Combines selected RGBA channels of a roto/matte image into one matte with proper union math (not max).
Roto Merge takes one input whose shapes live in RGBA channels and unions the channels you enable (red/green/blue/alpha checkboxes) using (a+b)-a*b style combine instead of a crude max.
Output can be Alpha-only or full RGBA. Meant for rotos delivered as multi-channel mattes where you want a clean combined matte without max-stack hacks.
set cut_paste_input [stack 0]
version 12.1 v4
push $cut_paste_input
Group {
name rotoMerge
tile_color 0x421010ff
selected true
xpos -1129
ypos 968
addUserKnob {20 User l rotoMerge}
addUserKnob {4 output l ouput M {Alpha RGBA "" ""}}
addUserKnob {6 red +STARTLINE}
addUserKnob {6 green +STARTLINE}
green true
addUserKnob {6 blue +STARTLINE}
blue true
addUserKnob {6 alpha +STARTLINE}
addUserKnob {26 ""}
addUserKnob {26 lbl l "" +STARTLINE T "RotoMerge v1.0"}
addUserKnob {22 btn l DerekVFX.ca T "nuke.tcl('start', 'https://derekvfx.ca')" +STARTLINE}
}
ChannelMerge {
inputs 0
name ChannelMerge1
xpos 254
ypos 309
}
Input {
inputs 0
name Input
xpos 447
ypos 61
}
set Ndf52000 [stack 0]
Expression {
expr0 "r * parent.red"
expr1 "g * parent.green"
expr2 "b * parent.blue"
expr3 "a * parent.alpha"
name Expression2
xpos 555
ypos 173
}
Expression {
temp_name0 rg
temp_expr0 "(r+g) - r*g"
temp_name1 ba
temp_expr1 "(b+a) - b*a"
temp_name2 out
temp_expr2 "(rg+ba) - rg*ba"
expr0 out
expr1 out
expr2 out
expr3 out
name Expression1
xpos 555
ypos 237
}
push $Ndf52000
MergeExpression {
inputs 2
expr0 "parent.output ? Aa : Br"
expr1 "parent.output ? Aa : Bg"
expr2 "parent.output ? Aa : Bb"
expr3 Aa
name MergeExpression1
xpos 447
ypos 314
}
Output {
name Output1
xpos 447
ypos 1055
}
end_group