A semi-automatic way to explode assemblies in ParaView & create simple plots that reveal the hidden parts in your models.

exploding-assemblies-in-paraview.md

Exploding Assemblies in ParaView

Accompanies OnCFD Newsletter #155: "Exploding assemblies in ParaView"

Attached is a minimal Python state file that can be used to re-create the required pipeline.

Needs ParaView v5.11 (or greater).

Save the state file locally, edit it to read one of your own geometry files & open it with File > Load State.

Then cross your fingers & hope for the best 🫣

For more info - see the original article 👋

ParaView_State_ExplodingAssembly.py

# state file generated using paraview version 5.11.1
import paraview
paraview.compatibility.major = 5
paraview.compatibility.minor = 11

#### import the simple module from the paraview
from paraview.simple import *
#### disable automatic camera reset on 'Show'
paraview.simple._DisableFirstRenderCameraReset()

# ----------------------------------------------------------------
# setup the data processing pipelines
#
# Edit the inputGeom to use your own geometry file
# ----------------------------------------------------------------

# create a new 'Wavefront OBJ Reader'
inputGeom = WavefrontOBJReader(registrationName='InputGeom.obj', FileName='/PATH/TO/YOUR_GEOMETRY_FILE_GOES_HERE.obj')

# create a new 'Compute Connected Surface Properties'
computeConnectedSurfaceProperties = ComputeConnectedSurfaceProperties(registrationName='ComputeConnectedSurfaceProperties', Input=inputGeom)

# create a new 'Programmable Filter'
programmableFilter = ProgrammableFilter(registrationName='ProgrammableFilter', Input=computeConnectedSurfaceProperties)
programmableFilter.Script = """

# Using the output of the previous filter 
input0 = inputs[0]

# Grab an object's centroid based on its ID & store it in a new field
data = input0.FieldData["ObjectCentroids"][input0.CellData["ObjectIds"]]

# Append the centroid field as cell data for use later
output.CellData.append(data, "Centroid")

# Append the object ID as cell data for use later
output.CellData.append(input0.CellData["ObjectIds"], "Id")

"""

# create a new 'Cell Data to Point Data'
cellDatatoPointData = CellDatatoPointData(registrationName='CellDatatoPointData', Input=programmableFilter)

# create a modified version of the original 'Centroid' vector
# this version exagerates the explosion in the Y & Z-directions & tones it down in the X-direction
# modify this to suit your requirements
calculator = Calculator(registrationName='Calculator', Input=cellDatatoPointData)
calculator.ResultArrayName = 'ToWarp'
calculator.Function = '(0.75*Centroid_X*iHat)+(1.1*Centroid_Y*jHat)+(2.2*Centroid_Z*kHat)'

# explode our assembly using 'Warp By Vector' & our new/tweaked 'ToWarp' Vector
warpByVector = WarpByVector(registrationName='WarpByVector', Input=calculator)
warpByVector.Vectors = ['POINTS', 'ToWarp']
warpByVector.ScaleFactor = 1.0


# ----------------------------------------------------------------
# setup views used in the visualization
# ----------------------------------------------------------------

# Create a new 'Render View'
renderView1 = CreateView('RenderView')
renderView1.CameraPosition = [-2525, 1327, 440]
renderView1.CameraFocalPoint = [-390, 58, -190]
renderView1.CameraViewUp = [0, 0, 1]
renderView1.CameraFocalDisk = 1.0
renderView1.CameraParallelScale = 663.607

SetActiveView(None)

# ----------------------------------------------------------------
# setup view layouts

# create new layout object 'Layout #1'
layout1 = CreateLayout(name='Layout #1')
layout1.AssignView(0, renderView1)

# restore active view
SetActiveView(renderView1)
# ----------------------------------------------------------------

# ----------------------------------------------------------------
# setup the visualization in view 'renderView1'

# show data from warpByVector
warpByVectorDisplay = Show(warpByVector, renderView1, 'GeometryRepresentation')

# get 2D transfer function for 'Id'
idTF2D = GetTransferFunction2D('Id')

# get color transfer function/color map for 'Id'
idLUT = GetColorTransferFunction('Id')
idLUT.TransferFunction2D = idTF2D
idLUT.RGBPoints = [0.0, 0.231373, 0.298039, 0.752941, 7.5, 0.865003, 0.865003, 0.865003, 15.0, 0.705882, 0.0156863, 0.14902]
idLUT.ScalarRangeInitialized = 1.0

# set some basic display properties
warpByVectorDisplay.Representation = 'Surface'
warpByVectorDisplay.ColorArrayName = ['POINTS', 'Id']
warpByVectorDisplay.LookupTable = idLUT

# ----------------------------------------------------------------
# restore active source
SetActiveSource(warpByVector)

renderView1.ResetCamera(True)
# ----------------------------------------------------------------