Tools for debugging Mesh Editing scripts (Index Visualizer and Debug mode)

I love many things about Blender, but debugging scripts that interact with Meshes is not one of them. It should be easy to visualize Edge / Vertex / Face indices. Don't worry, this isn't a rant without solution.

Exhibit 1

`bpy.app.debug = True` will add a set of options to the Display panel while in Edit Mode. The options are great but depending on theme and DPI the indices are difficult to make out. With softblend theme the overlay information borders on useless.

Exhibit 2

This script by Crouch, CoDEmanX and additions by me does pretty much the same but draws polygons behind the numbers for better contrast, this is customizable so usable no matter which theme you may be most comfortable with.

I'm quite happy with the script solution, it would be nice to have it available on each Blender installation as part of the `debug` mode. Anyone learning the ways of geometry related coding would benefit.

Improvements?

My underlay addition can be optimized by calculating the standard polygon once per possible width of index number. (quick implementation of said method) Further minimal mode would ditch the rounded corner and be much lighter, but if you have to visualize many vertex / edge / face indices you probably don't understand the algorithm you are trying to implement.

A guy walks into a bar - Asks a cycles nodes question.

Guy walks into a bar, poses a question. I'll restate without attribution.

Hello, I would like to do the following:
1. with existing Diffuse BSDF material
2. add input node of type Attribute
3. connect Attribute node output color to BSDF default (input)
4. Change the name socket of the "Attribute"

For sake of demonstration your material is the only material in the blend, so we can acces it by index=0, and it's a good idea to alias the material as mymat, purely for convenience

get active node:

mymat = bpy.data.materials[0]
mymat.node_tree.nodes.active

bpy and cycles have a large collection of methods and attributes, most of which vacate the mind within days of use, so i query the python console. this returns a list of nodes that we can add, looks like 'ATTRIBUTE' is on this list

mymat.node_tree.nodes.new('_')

add input node:

attr_node = mymat.node_tree.nodes.new('ATTRIBUTE')

This places the new node most likely in an inconvenient place, but gives you a reference to it: attr_node. The location of this attr_node defaults to vector((0.0, 0.0)). If we want to place the attr_node 200 units to the left of the Diffuse Node we need to know the location of the Diffuse Node.

dif_node = mymat.node_tree.nodes['Diffuse BSDF']
dif_loc = dif_node.location.copy()
attr_loc = dif_loc + Vector((-200.0, 0.0))

# update attr_node location
attr_node.location = attr_loc

Renaming the attr_node.attribute_name is the easiest bit

attr_node.attribute_name = 'kung fu'

Connecting the nodes i'm not sure about, let's try something..

# colour output node of attribute Node
attr_node.outputs['Color']

# colour input node of diffuse BSDF Node (shader)
dif_node.inputs['Color']

mymat.node_tree.links.new(attr_node.outputs['Color'],dif_node.inputs['Color'])

thus, to sum up.

# make sure for this particular script that you have the diffuse shader active, 
# before running it. else modify to satisfaction.

import bpy 
from mathutils import Vector

mymat = bpy.data.materials[0]
mymat.node_tree.nodes.active

attr_node = mymat.node_tree.nodes.new('ATTRIBUTE')
dif_node = mymat.node_tree.nodes['Diffuse BSDF']

# update attr_node location
dif_loc = dif_node.location.copy()
attr_loc = dif_loc + Vector((-200.0, 0.0))
attr_node.location = attr_loc

attr_node.attribute_name = 'kung fu'

output_node = attr_node.outputs['Color']
input_node = dif_node.inputs['Color']

mymat.node_tree.links.new(output_node, input_node)

i learnt a lot, thanks