######
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## Composite v0.1 by mf
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## DotCrawl() - creates dotcrawl. With configurable strength.
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##

function DotCrawl(clip input, int "strength") {

strength = Default(strength, 230)


BlankClip(pixel_type="yv12", length=input.framecount, width=Ceil(input.width/4),  \
height=Ceil(input.height/4))
black = last

black.Invert()
white = last

Interleave(black, white)
AssumeFieldBased().Weave()
TurnLeft()
Interleave(last, last.Invert)
AssumeFieldBased().Weave()
TurnRight()
PointResize(last.width*2, last.height*2)
Interleave(last, last.Invert)
Crop(0, 0, input.width, input.height)
DotCrawl = last

input.EdgeMask(3, 255, 255, 255, "sobel", Y=3, V=1, U=1).Levels(0, 2, 45, 0, 255) \
.Inflate().Inflate().Inflate().Inflate().Levels(0, 1, 100, 0, 255).Blur(1)        \
.Inflate().Inflate().Blur(1).Blur(1).Blur(1).Blur(1).Greyscale()
ymask = last

input.UToY().LanczosResize(last.width, last.height)
unorm = last

input.UToY().LanczosResize(last.width, last.height)
vnorm = last

BlankClip(unorm, color=$808080)
grey = last

YV12Subtract(grey, unorm.Invert(), tol=0).Levels(0, 1.5, 128, 0, 255)
ulight = last

YV12Subtract(grey, vnorm.Invert(), tol=0).Levels(0, 1.5, 128, 0, 255)
vlight = last

YV12Layer(ulight, vlight, "mul", 128)
Levels(0, 1, 255, 0, strength)
satmask = last

MaskedMerge(input, dotcrawl, ymask)
edgedots = last


MaskedMerge(input, edgedots, satmask)
}