Custom Defaults

from -- https://github.com/nortikin/sverchok/issues/1653

---

Node Defaults

When we (as coders) submit a node, we decide on sane defaults. Sometimes those defaults are not optimal for you (the user). If you find yourself always tweaking the parameters of a node before using it, then you might want to define custom node defaults. These are not the same as presets.

we can configure two things:

• (node props) any property on the node, including props that are not available from the UI
• (node function) we can write a function, (explained below) and call this function on a specific node whenever it is created.

We can now configure node defaults from a .json file located in ..datafiles/sverchok/node_defaults/. We can tell sverchok where to find this file by including the location of datafiles/sverchok in the user preferences of sverchok. It will look something like this:

datafiles/sverchok/node_defaults/node_defaults.json

{

    "SvGenNumberRange": {
        "props": [
            ["stop_float", 1.0],
            ["count_", 20],
            ["range_mode", "RANGE_COUNT"]
        ]
    },

    "SvVDExperimental": {
        "props": [], 
        "function": "view3d.init_vdmk3"
    }

}

All we have to do is create (key, value pair) for each node.

• key: ( the node's bl_idname)

• value: Currently the value accepts two directives (but can be extended later)

  1. props ( push props in sequence with a list of prop_name, prop_value pairs. )
  2. function ( push a function: in the example below the function is referenced as view3d.init_vdmk3. read that as filename.function and filename shall be located in datafiles/sverchok/node_defaults/ )

datafiles/sverchok/node_defaults/view3d.py

import random
import colorsys

import bpy


def init_vdmk3(node):

    def fold_color(color, shift):
        h, s, v = colorsys.rgb_to_hsv(*color)
        return list(colorsys.hsv_to_rgb(shift, s, v))

    A = [0.938000, 0.948000, 0.900000, 1.000000]
    B = [0.500000, 0.752000, 0.899000, 1.000000]
    C = [0.030100, 0.488000, 0.899000, 1.000000]

    shift = random.random()
    node.vertex_color = fold_color(A[:3], shift) + [1.0]
    node.edge_color = fold_color(B[:3], shift) + [1.0]
    node.face_color = fold_color(C[:3], shift) + [1.0]

    node.line_width = 1.0
    node.point_size = 2.0

this default function will generate nicely shifted colour palettes for the viewer node, whenever you add a new viewnode with that bl_idname, like this

---

Each time you add a node, the node_default_dict is checked if the bl_idname has an entry.

• this has no effect on nodes that you duplicate, they clone their properties according to self.copy()
• this doesn't offer a visual way to set the preferences yet, that would be the next step.