Python - How to insert knots in c4d.Gradient

Vladislav Borovikov

Hello everyone!
I'm trying to add knots to the c4d.Gradient object, in GvNode. But the changes are not applied to the parameter, maybe I missed something, and this parameter needs to be updated?

import c4d
import redshift

knots = [
    (c4d.Vector(1,0,1), 0.25, 0.25, 0.25),
    (c4d.Vector(0,1,1), 0.5, 0.5, 0.5),
    (c4d.Vector(1,1,0), 0.75, 0.75, 0.75),
    
]

def main() -> None:
    rs_material = doc.GetActiveMaterial()
    if not rs_material.GetTypeName() == "RS Shader Graph":
        print(rs_material.GetTypeName())
        return
    
    # Get node master and root
    nm = redshift.GetRSMaterialNodeMaster(rs_material)
    root = nm.GetRoot()
    
    # Create RSRamp gvNode
    ramp_node = nm.CreateNode(root, 1036227)
    ramp_node[c4d.GV_REDSHIFT_SHADER_META_CLASSNAME] = 'RSRamp'
    
    # Get Gradient
    gradient = ramp_node[c4d.REDSHIFT_SHADER_RSRAMP_RAMP]
    gradient.FlushKnots()
    for i, knot in enumerate(knots):
        gradient.InsertKnot(knot[0], knot[1], knot[2], knot[3], i )
    
    #  Check values
    for i in range(gradient.GetKnotCount()):
        knot = gradient.GetKnot(i)
        col = knot.get("col")
        pos = knot.get("pos")
        br = knot.get('brightness')
        print(f"col = {col}, pos = {pos}, brightness = {br} ")

main()

i_mazlov

Hi @Vladislav-Borovikov,

Welcome to the Maxon developers forum and its community, it is great to have you with us!

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About your First Question

Custom datatypes implement copy constructor, which effectively means that at the line

gradient = ramp_node[c4d.REDSHIFT_SHADER_RSRAMP_RAMP]

you copy c4d.Gradient from the node and store it in variable 'gradient'. All further interactions are performed with this local copy of the gradient. In order to apply them back to the node you need to assign your local variable after modifications back to the node:

ramp_node[c4d.REDSHIFT_SHADER_RSRAMP_RAMP] = gradient

Cheers,
Ilia

Vladislav Borovikov

Thank you very much, @i_mazlov! This is what I needed!