# Attach arrow to mesh
**URL:** https://discourse.paraview.org/t/attach-arrow-to-mesh/2691
**Category:** ParaView Support
**Created:** [October 4, 2019, 2:32pm UTC](https://discourse.paraview.org/t/attach-arrow-to-mesh/2691 "2019-10-04T14:32:46Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@eelcovanvliet](https://discourse.paraview.org/u/eelcovanvliet)
#### Post date: [October 4, 2019, 2:32pm UTC](https://discourse.paraview.org/t/attach-arrow-to-mesh/2691/1 "2019-10-04T14:32:46Z")
Hi all,
I have a mesh data set that I can deform using Warp by Vector filter. I also have another data set containing a single force vector (at location [0,0,0], with components [fx(t),fy(t),fz(t)]. I can use Transform filter to move that vector about, but I really want to attach it to a point of the mesh (or something to that effect). Any suggestions?
Kind regards, Eelco
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [October 7, 2019, 3:10am UTC](https://discourse.paraview.org/t/attach-arrow-to-mesh/2691/2 "2019-10-07T03:10:17Z")
Not very clear. Maybe you are looking for RessampleWithDataset filter ? Or Glyph ?
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### Author:  [@eelcovanvliet](https://discourse.paraview.org/u/eelcovanvliet)
#### Post date: [October 9, 2019, 1:36pm UTC](https://discourse.paraview.org/t/attach-arrow-to-mesh/2691/3 "2019-10-09T13:36:07Z")
Sorry for the belated response.
I added some files in an attempt to clarify my question. The mesh consist of just a few random elements due to confidentiality, but i’ll do for now.
“eturret” is a dataset containing the mesh and has attributes displacement and deformation. Only Deformation has values, the displacement is all zero for now.
“mooring” is a dataset containing the data of a force vector.
I use Glyph to create an arrow for the mooring dataset. But I want to move (attach) the base of that arrow to a point on the mesh. _Any_ point really. And I want it to follow that point, even if I apply the Warp by Vector filter to the mesh.
Hopefully this clarifies a little!
[eturret.h5](https://discourse.paraview.org/uploads/short-url/gUh87OcK9TGXWzP234kt5sZ8pa6.h5) (129.9 KB) [eturret.xmf](https://discourse.paraview.org/uploads/short-url/2LBvuWpZfOe9TTgPtVKYld16l7t.xmf) (45.1 KB) [mooring.h5](https://discourse.paraview.org/uploads/short-url/e60lFxuEdGaGlHSIqUSTLEhiO0T.h5) (41.2 KB) [mooring.xmf](https://discourse.paraview.org/uploads/short-url/xN23q8eATCmlQmy22ti2StFegWI.xmf) (35.3 KB) [test.pvsm](https://discourse.paraview.org/uploads/short-url/wDOW8wRsBJjVEaEP9aBKeVZJdLN.pvsm) (564.2 KB)
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [October 10, 2019, 2:00am UTC](https://discourse.paraview.org/t/attach-arrow-to-mesh/2691/4 "2019-10-10T02:00:21Z")
There is not direct way to do that.
But there is the “specific” way and the “convoluted” way.
For the specific way, you will need to implement a simple programmable filter that will take two inputs, the mesh and the mooring, and copy the mooring vector into each points of the mesh. You can then use a glyph without any issue. You still need to implement it in python. Let me know if you need help.
[https://www.paraview.org/Wiki/Python\_Programmable\_Filter](https://www.paraview.org/Wiki/Python_Programmable_Filter)
The convoluted way is a bit more tricky but does not require any python. Here it is :
[testConvoluted.pvsm](https://discourse.paraview.org/uploads/short-url/9ONvE6JuN8Lwv8T8oB9qkNtJ9w6.pvsm) (834.6 KB)
The idea of this is that we consider your Arrow Glyph as a source input for a Glyph with custom source applied on the mesh. The problem is that your mooring is not located in the origin on the space, so I had to translate it. If the translation is constant with all your moorings or if this translation can be removed in post-process, this solution might be acceptable.
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### Author:  [@eelcovanvliet](https://discourse.paraview.org/u/eelcovanvliet)
#### Post date: [October 25, 2019, 12:47pm UTC](https://discourse.paraview.org/t/attach-arrow-to-mesh/2691/5 "2019-10-25T12:47:03Z")
I managed to get it working using the programmable filter. The script will attach the vector to the nearest node wrt to the coordinates you put in manually. Here’s how I went about it:
1. Put the mesh, the **warped** mesh and the mooring (vector) in a GroupDataSet
2. Push the GroupDataSet through a programmable filter with the code below.
```auto
import numpy as np
# Input coordinates. The script will find the nearest node in the mesh.
x,y,z = 0,0,-1e3
input = self.GetInputDataObject(0, 0)
iter = input.NewIterator()
iter.UnRegister(None)
iter.InitTraversal()
# Warped mesh data set
curInput1 = iter.GetCurrentDataObject()
iter.GoToNextItem()
# Vector data set
curInput2 = iter.GetCurrentDataObject()
iter.GoToNextItem()
# Mesh data set
curInput3 = iter.GetCurrentDataObject()
# initialize currOutput
curOutput = curInput2.NewInstance()
curOutput.UnRegister(None)
curOutput.ShallowCopy(curInput2)
# create output and attach curOutput
output = self.GetOutputDataObject(0)
output.CopyStructure(input)
output.SetDataSet(iter, curOutput)
loc = []
NrOfPt = curInput3.GetNumberOfPoints()
for i in range(0,NrOfPt):
loc.append(curInput3.GetPoint(i))
loc = np.asarray(loc)
loc[:,0]-=x
loc[:,1]-=y
loc[:,2]-=z
lsq = lambda x: x[:,0]**2+x[:,1]**2+x[:,2]**2
NodeNr = np.argmin(lsq(loc))
# Set currOutput to the node
loc = curInput1.GetPoint(NodeNr)
newPoints = vtk.vtkPoints()
newPoints.InsertPoint(0,loc[0],loc[1],loc[2])
curOutput.SetPoints(newPoints)
```
1. Create an arrow glyph.
DRAWBACK:
Slow. Every time step the nearest node is calculated (which is always the same). It would be better to do this calculation independent of time, but I don’t know how to do that yet. Any advice is welcome!
KR, Eelco