Apple Shake 4 - Manual (Page 942)

942 Chapter 31 Expressions and Scripting
The following table shows channel variables used in nodes such as ColorX, LayerX,
Reorder, etc. Check the documentation for specific support of any variable.
bytes The number of bytes in that image. This takes the input bit depth
when called from inside of the node, and the output bit depth
when called from outside of the node.
width Width of the image. Takes the input width when called from inside
of the node, and the output width when called from outside of the
node.
height Height of the image. Takes the input height when called from
inside of the node, and the output height when called from
outside of the node.
_curImageName Returns the name of the actual file being used for the current
frame. Useful when plugged into a Text node:
{FileIn1._curImageName}
dod[0], dod[1], dod[2], dod[3] The variable for the Domain of Definition (DOD): xMin, yMin, xMax,
yMax, respectively.
Image Variables Definition
In-Node Variables Definition
nr, ng, nb, na, nz New red, green, blue, alpha, Z channel.
r, g, b, a, z Original red, green, blue, alpha, Z channel.
l Luminance channel for Reorder.
n Null channel. Strips out the alpha in Reorder when used like
this: rgbn
r2, g2, b2, a2, z2 Second image’s channel for LayerX.
Math Functions Definition
abs(x) Integer absolute value. abs(-4) = 4. Be careful, as this returns an
integer, not a float. Use fabs for float.
biasedGain(value, gain, bias) Gives a ContrastLum-like curve that gives roll-off between two
values.
cbrt(x) Cubic root. cbrt(8) = 2
ceil(x) Truncates to next integer. ceil(5.3) = 6
clamp(x, lo, hi) Clamps x to between lo and hi.
clamp(1.5,0,1) = 1
exp(x) Natural exponent. exp(0) = 1
fabs(x) Float absolute value. fabs(-4.1) = 4.1
floor(x) Truncates to next lowest integer. floor(5.8) = 5
fmod(x,y) Float modulus. Returns the remainder in float. fmod(11.45,3) = 2, for
example, (3x3+2.45 = 11.45)
log(x) Natural log. log(1) = 0