# Convert curve to mesh with specified resolution via API

I am looking for a way to convert a curve into a mesh with specified resolution via Python API. For example, a 100 m curve should be turned into a mesh where vertices are placed every 1 m along the curve, irrespective of the number or position of the original curve segments/control points. The type of the curve is not important, let's say it is a Nurbs path.

If there is no simple way to achieve that, is it possible to get coordinates of a point at a specified distance or percentage of length along the curve? (From here it should be possible to achieve the desired result using calc_length).

I am aware of tricks with constraints and animation, but perhaps it could be done in a more direct manner.

• check out this answer here: blender.stackexchange.com/questions/93391/… this should help Commented Mar 29, 2023 at 19:08
• What if the length of the curve is not divisible by specified length? Geometry Nodes have an option to do that (and dynamically creating a geonodes tree might be more performant than doing it in Python if the curve is to be divided to a lot of segments or if there's a lot of curves). Commented Mar 29, 2023 at 19:15
• The divisibility of the length of the curve is of no importance in my task. I can choose the length of the segment based on the total length, the requirement is only that the points are evenly spaced (which wouldn't be the case if I simply subdivided the segments of the original curve). And even this requirement can be relaxed a bit, i.e. if I have, say, 9 segments of 1 m each and the tenth is 0.95 m. I don't expect the number of segments to exceed 1-1.5 thousand, or let's say 10 thousand in the most extreme cases, and the number of curves is in single figures at most. Commented Mar 30, 2023 at 5:48
• Space operator from looptools github.com/sobotka/blender-addons/blob/master/mesh_looptools.py Commented Mar 30, 2023 at 14:37

This can be done in Geometry nodes easily:

You can create this geometry nodes tree and use it in Python, or you can create it dynamically in Python. I think it's reasonable, because finding out the position of the points is a computationally expensive process (basically trial-and-error), which multiplied by thousands of segments probably would end up too expensive in Python - meaning that the overhead of evaluating the depsgraph and the object is likely worth it.

from bpy import context as C, data as D

ob = C.object
mod = ob.modifiers.new(name="Temp geonodes modifier", type='NODES')
tree = D.node_groups.new("Temp geonodes tree", 'GeometryNodeTree')
tree.inputs.new('NodeSocketGeometry', 'Geometry')
tree.outputs.new('NodeSocketGeometry', 'Geometry')

node_in = tree.nodes.new(type='NodeGroupInput')
node_ctp = tree.nodes.new(type='GeometryNodeCurveToPoints')
node_ctp.mode = 'LENGTH'
node_ctp.inputs['Length'].default_value = 0.2
node_ptv = tree.nodes.new(type='GeometryNodePointsToVertices')
node_out = tree.nodes.new(type='NodeGroupOutput')

mod.node_group = tree
dg = C.evaluated_depsgraph_get()
ev = C.object.evaluated_get(dg)
me = ev.to_mesh()
print("Coordinates:", *[v.co for v in me.vertices], sep="\n")
ob.modifiers.remove(mod)
D.node_groups.remove(tree)

• Yes, I will have to construct depsgraph for other purposes anyway. As for the solution with geometry nodes, I am not yet sufficiently familiar with this feature, will have to look at it in more detail. Have always been more at home with plain old programming. Thanks! Commented Mar 30, 2023 at 12:21
• Using geonodes in Python is interesting, because Python is slow, while the implementation of geonodes is in C++. Commented Mar 30, 2023 at 12:25