interpolation node

[ly29]

First and simple, linear interpolation.

[enzyme69]

Very nice!!! Ok, I think I was doing something that need this, I can now proceed.

Smooth vertex/vertices or Average Vertices will complete this :)

[ly29]

Needs some more work before I push... Spline will come a bit later I think.

[zeffii]

I think this is exactly what spline normalize does, in conjunction with this node script

[ly29]

Was playing a bit with numpy and thought this was good application for it.

            for v,t_in in zip(verts,repeat_last(t_ins)):
                pts = np.array(v).T
                tmp = np.apply_along_axis(np.linalg.norm,0,pts[:,:-1]-pts[:,1:])
                t = tmp/tmp.sum()
                t = np.insert(t,0,0)
                t = t.cumsum()
                t_corr = [min(1, max(t, 0)) for t in t_in]
                # this should also be numpy
                out = [np.interp(t_corr, t, pts[i]) for i in range(3)]
                verts_out.append(list(zip(*out)))

[ly29]

Hadn't looked at your code.

[zeffii]

i'm not ashamed to say I have no notion of what that code does without picking it apart line by line :D

[ly29]

As a hint it makes a function f(t)=x,y,z with t= [0,1] based on the distance between input points. Then it evaluates f(t) for the t input values from the interval after making sure they are in the interval.

[nortikin]

yes, based on existing edges - that what we need

[ly29]

Let us explain numpy code to share knowledge. inputs, v is sverchok list of vertices [v0,v1,v2], t_in is a list of points to evaluate in [0,1]

            for v,t_in in zip(verts,repeat_last(t_ins)):
                pts = np.array(v).T #make a np array
                # calc the distance between points
                tmp = np.apply_along_axis(np.linalg.norm,0,pts[:,:-1]-pts[:,1:])
                # resize by inserting 0 and get cumulative sum
                t = np.insert(tmp,0,0).cumsum()
                # normalize t by dividing all values with the sum, t[-1] 
                t = t/t[-1]
                # ensure that all t values to evaled are in [0,1]
                t_corr = [min(1, max(t, 0)) for t in t_in]
                # interpolate X,Y,Z using np.interp
                out = [np.interp(t_corr, t, pts[i]) for i in range(3)]
                verts_out.append(list(zip(*out)))

[ly29]

Spline was tricker than I thought. First attempt has some problem to say the least.

[zeffii]

is that a separate spline segment between each vertex?

[ly29]

it is natural cubic spline based on the points. It should be smooth and pass through each points. Double fail.

[zeffii]

headwrecking as that seems, it looks like an interesting problem to solve. note to self : poly bezier

[ly29]

I taking code from code from numerical recipes in C, since the problem is around the points I suspect numerical error. If increase the number of points it works better, however splines are supposed to be stable even with small inputs. Hmm. 20 input points instead of 10.

[ly29]

But still error around the input points...

[ly29]

It doesn't say that does it? If t is numpy array that we used cumsum() on then t[-1] is max of the orignal array. Then we normalize the values between 0,1 with that line.

>>> t=np.linspace(0,10,6)
>>> t
array([  0.,   2.,   4.,   6.,   8.,  10.])

>>> t=t.cumsum()
>>> t
array([  0.,   2.,   6.,  12.,  20.,  30.])

>>> t/t[-1]
array([ 0.        ,  0.06666667,  0.2       ,  0.4       ,  0.66666667,  1.        ])

[ly29]

Okay I won't have time to finish this soon. Will push the linear code soon and leave spline for a bit later.

[zeffii]

I get this error on startup with now: I'll update My blender build to see if the error goes.

Sverchok_nodes: added to pythonpath :-)
Have a nice day with Sverchok
Traceback (most recent call last):
  File "C:\blender_trunk\2.70\scripts\modules\addon_utils.py", line 299, in enable
    mod = __import__(module_name)
  File "C:\blender_trunk\2.70\scripts\addons\sverchok-master\__init__.py", line 279, in <module>
    import node_Interpolation
  File "C:\blender_trunk\2.70\scripts\addons\sverchok-master\..\sverchok-master\node_Interpolation.py"
, line 4, in <module>
    import numpy as np
  File "C:\blender_trunk\2.70\python\lib\site-packages\numpy\__init__.py", line 153, in <module>
    from . import add_newdocs
  File "C:\blender_trunk\2.70\python\lib\site-packages\numpy\add_newdocs.py", line 13, in <module>
    from numpy.lib import add_newdoc
  File "C:\blender_trunk\2.70\python\lib\site-packages\numpy\lib\__init__.py", line 8, in <module>
    from .type_check import *
  File "C:\blender_trunk\2.70\python\lib\site-packages\numpy\lib\type_check.py", line 11, in <module>
    import numpy.core.numeric as _nx
  File "C:\blender_trunk\2.70\python\lib\site-packages\numpy\core\__init__.py", line 6, in <module>
    from . import multiarray
ImportError: Module use of python33.dll conflicts with this version of Python.

the python version is

PYTHON INTERACTIVE CONSOLE 3.4.0 (default, Apr 30 2014, 14:55:04) [MSC v.1500 32 bit (Intel)]```

[ly29]

That sounds like blender issue numpy.

[zeffii]

it's about time I upgrade to 3.4 locally anyway - cool, local install of Py 3.4 and numpy for that version, then renamed the python folder in blender to _python so blender uses my local python install. Works now.

[zeffii]

Maybe a note to this effect should be added to the readme.md - new section TroubleShooting Installation issues

[ly29]

What blender version does this happen with? Please file bug report if it is an official build. There isn't any reason that shouldn't work, if it is to widespread lets disable interpolation node for now.

[ly29]

So got it working, now, made really stupid indexing mistake earlier. But sadly this code cannot be used with sverchok due to licensing issues. Removed it from github and starting over...

[zeffii]

The openNURBS sdk has a very liberal license

[ly29]

Looptools has python implementation that is gpl I just saw, simpler to copy I imagine.

[zeffii]

going to be awesome. Thanks for this!

[ly29]

The code is certainly less elegant now but that we can work on later. Also should have an option to ensure output point distribution, but then we need to calculate each spline segment length and map input to that.

[ly29]

Todo:

• [ ] Mode to ensure even distribution of output points
• [ ] Cyclic splines
• [ ] Edge input to get order of points from edges.

And add spline code to curve utils.

[nortikin]

https://github.com/nortikin/sverchok/issues/204#issuecomment-44951998 just link for images.

[nortikin]

:-1: POLS 2 EDGS Updated Float Series.001 in:0.0002 Updated Objects_in in:0.0024 Updated Interpolation.001 in:0.0424 Updated List Flip Node in:0.0018 Updated Interpolation in:0.1822 Updated Line Connect in:0.0106 Updated Polygons 2 Edges in:2.1216 Updated Float in:0.0001 Updated Vector Normal in:0.0284 Updated Vectors Move in:0.0196 Updated Viewer Draw in:0.0122 Updated Viewer Draw.001 in:0.0183 Updated Float in:0.0001 Updated Vectors Move in:0.0166 Updated Viewer Draw.001 in:0.0129

[enzyme69]

Why Polygons 2 Edges is gone?

[nortikin]

i just marked it, don't know how underline on github

[ly29]

Hint for pols2edges: Create a set of edges for each object, test for membership in list is a slow operation. This line:

if this not in edgs and this not in object:

    def polstoedgs(self, pols):
        out = []
        for obj in pols:
            object = []
            for pols in obj:
                edgs = []
                for i, ind in enumerate(pols):
                    this = [ind, pols[i-1]]
                    this.sort()
                    if this not in edgs and this not in object: 
                        edgs.append(this)
                object.extend(edgs)
            out.append(object)
        return out

[nortikin]

is there case with collections librery... i will rethink this node.

[ly29]

@nortikin test now I did this:

    def pols_edges(self,obj):
        out = []
        for faces in obj:
            out_edges = set()
            for face in faces:
                for edge in zip(face,face[1:]+[face[0]]):
                    out_edges.add(tuple(sorted(edge)))
            out.append(list(out_edges))
        return out

[ly29]

Old: Updated Cylinder in:0.0177 Updated Polygons 2 Edges in:0.9626 Updated Viewer Draw in:0.0084 New: Updated Cylinder in:0.0174 Updated Polygons 2 Edges in:0.0308 Updated Viewer Draw in:0.0187

So 3% of original time, lets be nice and call a factor of 2 improvements, should also scale much better. Settings for cylinder: Verts: 32, subdivisions 53.

[nortikin]

wow!!! i just thought of set() and this collection functions. yes, this is solution.

[nortikin]

afraid to ask. am i did wrong that asked evaluate point on surface? by uv coordinates to exact point on surface? Because i asked interpolation of developer, and he agreed to make this feature for API. if it is not ok, than we should stop asking. Can we find points by UV coordinates on nurbs?

[ly29]

as you saw we can make spline interpolated surfaces now, but this is an important feature and it should be part of api for nurbs if it isn't already.

[nortikin]

it isn't. yes, anyway it will become part. but we have ours needs.