1
$\begingroup$

Current very slow method (code reduced):

    obj = bpy.context.active_object
    vgroups = obj.vertex_groups.new(name="test_layer")

    for loop in obj.data.loops:
        vindex = obj.data.loops[loop.index].vertex_index
        vgroups.add([vindex], value, "REPLACE")

Performance is tested on 1024 x 1024 grid and takes minutes to complete for several weight layers.

My goal is not to assign the same weight value, but different values for each vertex.

I believe I am looking for something like below, which does not exist.

active_object.vertex_groups[group_name].foreach_set()

$\endgroup$
2
  • 1
    $\begingroup$ As noted in answer below, loop over verts not loops. 8 verts in cube, 24 loops. Also content that loop is obj.data.loops[loop.index] in code above. $\endgroup$ – batFINGER Dec 7 '20 at 14:35
  • $\begingroup$ @batFINGER that is a good point, I did not think about that and will rewrite to use vertex index instead. I was using loops to get UV data for that vertex, but maybe even that is not necessary. $\endgroup$ – VSB Dec 7 '20 at 15:01
0
$\begingroup$

Usage of loops here is not clear.

You can:

import bpy

obj = bpy.context.active_object
vgroup = obj.vertex_groups.new(name="test_layer")

value = 0.5

for i in range(len(obj.data.vertices)):
    vgroup.add( [i], value, 'REPLACE')

We add vertices to a group, using their indexes.

The documentation is here:

add(index, weight, type)

Add vertices to the group

Parameters
        index (int array of 1 items in [-inf, inf]) – Index List
        weight (float in [0, 1]) – Vertex weight
        type (enum in ['REPLACE', 'ADD', 'SUBTRACT']) –
        Vertex assign mode
            REPLACE Replace, Replace.
            ADD Add, Add.
            SUBTRACT Subtract, Subtract.
$\endgroup$
9
  • $\begingroup$ I am using loops due to other processes in the function. The method you provided is the same one I use and is very slow. For example to batch set vertex colors this should work active_object.data.vertex_colors[0].data.foreach_set(new_color_set) $\endgroup$ – VSB Dec 6 '20 at 22:23
  • $\begingroup$ OK. I tested what I propose on over a million of vertices, it is nearly instant (maybe 1s). $\endgroup$ – lemon Dec 7 '20 at 7:07
  • $\begingroup$ If you use data.loops and want to 'replace' the weight, you're just doing it several times. Why are you talking about vertex colors now? $\endgroup$ – lemon Dec 7 '20 at 7:36
  • $\begingroup$ No need for loop with constant value (value = 0.5 as coded above) vg.add(range(len(obj.data.vertices)), value, 'REPLACE') $\endgroup$ – batFINGER Dec 7 '20 at 14:31
  • $\begingroup$ @batFINGER. Sure but he ask for several values. "My goal is not to assign the same weight value, but different values for each vertex." $\endgroup$ – lemon Dec 7 '20 at 14:34

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.