Add points and lines using Python VTK callback function with timer

line.py

#!/usr/bin/env python

# TODO:
# - Starting point!
# - Use Queue with multi-threading

import vtk
from datetime import datetime
import paho.mqtt.client as mqtt

class vtkTimerCallback():
    def __init__(self, pts, lines):
        self.timer_count = 0
        self.pts = pts
        self.lines = lines
        self.p2 = [] # Need to lock?
        self.changed = False
        
        self.client = mqtt.Client()
        self.client.on_connect = self.on_connect
        self.client.on_message = self.on_message
        self.client.connect_async("localhost", 1883, 60)

    def on_connect(self, client, userdata, flags, rc):
        print("MQTT connected with result code "+str(rc))
        client.subscribe("hello/world")

    def on_message(self, client, userdata, msg):
        t = datetime.utcnow().isoformat()
        data = msg.payload.split(' ')
        x = float(data[0])
        y = float(data[1])
        z = float(data[2])
        self.p2 = [x, y, z]
        self.changed = True
        
    def execute(self, obj, event):
        self.actor.GetProperty().SetColor(1,1,0)

        self.changed = False
        self.client.loop_start()
        self.client.loop_stop()
        
        if self.changed == True and self.p2:
            print self.changed, self.p2
            m = self.actor.GetMapper()
            linesPolyData = m.GetInput()
            l = linesPolyData.GetLines()
            number_of_lines = int(l.GetNumberOfCells())
            
            self.pts.InsertNextPoint(self.p2)

            print self.p2, number_of_lines
            line2 = vtk.vtkLine()
            line2.GetPointIds().SetId(0, number_of_lines)
            line2.GetPointIds().SetId(1, number_of_lines+1)
            self.lines.InsertNextCell(line2)

            linesPolyData.SetPoints(self.pts)
            linesPolyData.SetLines(self.lines)
        else:
            print "Else"
            
        self.actor.GetProperty().SetColor(0,1,1)

        iren = obj
        iren.GetRenderWindow().Render()
        self.timer_count += 1
    
def main():
    origin = [0.0, 0.0, 0.0]
    p0 = [1.0, 0.0, 0.0]
    p1 = [0.0, 1.0, 0.0]

    pts = vtk.vtkPoints()
    pts.InsertNextPoint(origin)
    pts.InsertNextPoint(p0)
    pts.InsertNextPoint(p1)
 
    line0 = vtk.vtkLine()
    line0.GetPointIds().SetId(0,0) # the second 0 is the index of the Origin in the vtkPoints
    line0.GetPointIds().SetId(1,1) # the second 1 is the index of P0 in the vtkPoints

    line1 = vtk.vtkLine()
    line1.GetPointIds().SetId(0,0) # the second 0 is the index of the Origin in the vtkPoints
    line1.GetPointIds().SetId(1,2) # 2 is the index of P1 in the vtkPoints

    lines = vtk.vtkCellArray()
    lines.InsertNextCell(line0)
    lines.InsertNextCell(line1)
 
    linesPolyData = vtk.vtkPolyData()

    linesPolyData.SetPoints(pts)
    linesPolyData.SetLines(lines)

    mapper = vtk.vtkPolyDataMapper()
    mapper.SetInputData(linesPolyData)
 
    actor = vtk.vtkActor()
    actor.SetMapper(mapper)
 
    renderer = vtk.vtkRenderer()
    renderWindow = vtk.vtkRenderWindow()
    renderWindow.AddRenderer(renderer)
    renderWindowInteractor = vtk.vtkRenderWindowInteractor()
    renderWindowInteractor.SetRenderWindow(renderWindow)
    renderer.AddActor(actor)
 
    renderWindow.Render()

    cb = vtkTimerCallback(pts, lines)
    cb.actor = actor
    renderWindowInteractor.AddObserver('TimerEvent', cb.execute)
    timerId = renderWindowInteractor.CreateRepeatingTimer(2000);

    renderWindowInteractor.Start()

if __name__ == '__main__':
    main()