Drawing points and lines with COMPAS for Blender

Hi,

I’m really excited to start learning COMPAS and though the best way to get my head around was to port a couple of sketches I did in Processing.

To get me started I would like to know how to draw some points and lines in Blender, play with it, connect them, etc…

I see COMPAS has different classes named compas_blender.utilities. draw_points, compas_blender.utilities. draw_pointcloud or VolMeshArtist. draw_points. Could someone kindly explain:

  • if they are appropriate to draw points (in Blender)
  • how they differ
  • how to use them

I tried the following (extracting vertices from a .obj and display them as points):

import compas

from compas_blender import utilities
from compas_blender.artists import NetworkArtist
from compas.datastructures import Network



# make a network from sample data

network = Network.from_obj(compas.get("C:/Users/solub/Desktop/rocket.obj"))

xyz   = network.get_vertices_attributes(('x', 'y', 'z'))


utilities.draw_points(d)

… but got a AttributeError: 'int' object has no attribute 'get' . Does this mean I have to store the vertices in a dictionnary or convert the list array to another data type ?

Hi @solub,

If you already have your geometry in a Datastructure like the Network in your example, it would be easiest to draw vertices using the NetworkArtist:

import compas

from compas.datastructures import Network
from compas_blender.artists import NetworkArtist
from compas_blender.utilities import clear_layer


network = Network.from_obj(compas.get('grid_irregular.obj'))

artist = NetworkArtist(network=network, layer='Collection')

clear_layer(layer='Collection')

artist.draw_vertices(radius=0.1)
artist.draw_vertexlabels()

Blender doesnt have a Point type of object, so I plot the closest thing I could find, an Empty object, which you can change its size with the radius argument. The code above would produce the following:

You are on the right track with the draw_points() function, you need to give it a list of point dict data, for example:

import compas

from compas.datastructures import Network
from compas_blender.utilities import clear_layer
from compas_blender.utilities import draw_points


network = Network.from_obj(compas.get('grid_irregular.obj'))

xyz = network.get_vertices_attributes('xyz')

clear_layer(layer='Collection')

points = [{'pos': i, 'radius': 0.1} for i in xyz]

draw_points(points=points)

If you use draw_pointcloud(points=points) instead (without radius which isn’t needed), you will get a bunch of Mesh objects with just one vertex, which will plot quite efficiently even for many thousands of points as Blender renders meshes efficiently. Your points then appear as a single vertex Mesh for each point.

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Thank you so much for the swift and comprehensive reply. That helps a lot.

Very welcome. You could join all the mesh points in the last example with CTRL+J if you wanted one mesh.

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