feed Cd to color ramp point inside shader?

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Hello!

I am trying to set the value of a color ramp point inside a shader to the value of my Cd.
The parameter is called “rampcolordefault2” and i guess in vex i could have written “rampcolordefault2 = @Cd;”, but this is vops and i just don't know how to set that parameter.Is there any way of doing this?

Thank you!

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The ramp cannot take individual inputs as keys of the ramp. You can use the spline vop to evaluate a set of arbitrary inputs as if it were a ramp though. The spline vop unfortunately does not allow specifying key positions, limiting it to ramps with evenly spaced keys. If you want to have the full power of a ramp, you'll need to get crafty with building the arrays that define a ramps keys, positions, and bases. These in turn are evaluated using the spline() function, which is only available as inline code, using an inline or snippet vop.
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You can control ramps with python though, so you could put together an hda controlling this. Here is some example code to fiddle with.
node = hou.node('/obj/matnet1/subnet1/ramp1')
curve = hou.rampBasis.CatmullRom

pos1 = 0
pos2 = 0.5
pos3 = 1

firstColor = (0,1,0)
secondColor = (0,0,1)
thirdColor = (1,0,1)

newramp = hou.Ramp( (curve, curve, curve) , (pos1, pos2, pos3), (firstColor, secondColor, thirdColor))
node.setParms( {'rampcolordefault': newramp } )

-b
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