How to position instances of geometry nodes?

Question

I would like to create a precise number of geometry nodes and then position each instance based on some code.

The only way I found to place these instances is the apply the modifier, separate by loose part and then change the coordinates of each created object. However is there a way I can do that directly within the node tree, by e.g. passing a vector list as input to the Points Positions node ?

Answer 1

One way to bring an arbitrary list of positions into geometry nodes is to encode the positions into a texture.

testList.txt:

0.5 0.5 0.5
0 0 0
1 1 1 
1 0 0
0 1 0
0 0 1
-0.5 -0.5 -0.5
-0.8 -0.8 -0.8

EncodeVectorList.py:

import bpy
import csv

filepath = bpy.path.abspath("//testList.txt")

results = []
with open(filepath) as csvfile:
    reader = csv.reader(csvfile, delimiter=' ', quoting=csv.QUOTE_NONNUMERIC) # change contents to floats
    for row in reader: # each row is a list
        results.append(row)

# The 8 here is the number of points
img = bpy.data.images.new("testImg", 8, 1, alpha=False, float_buffer=True, is_data=True)

# Adds an unused alpha channel for formatting reasons and flattens the list
img.pixels = [item for sublist in [color + [1.0] for color in results] for item in sublist]

For Blender at least, colors are stored as floats, so any position values should be valid.

Node setup and result:

Make sure to set interpolation to closest on the Image Texture node.