# Difference between revisions of "VTK/Examples/Python/GeometricObjects/ParametricObjectsDemo"

< VTK‎ | Examples‎ | Python

## Description

See Parametric Equations for Surfaces by Andrew Maclean for an excellent description of these beautiful parametric surfaces.

This example also demonstrates how to manipulate lists of VTK objects using lists. Notice how parameters of the various Parametric Objects are accessed and set in the parametricObjects list.

## ParametricObjectsDemo.py

```#!/usr/bin/env python

import vtk
import random

class ParametricObjects():

def ParametricObjects(self):

parametricObjects = list()
parametricObjects.append(vtk.vtkParametricBoy())
parametricObjects.append(vtk.vtkParametricConicSpiral())
parametricObjects.append(vtk.vtkParametricCrossCap())
parametricObjects.append(vtk.vtkParametricDini())

parametricObjects.append(vtk.vtkParametricEllipsoid())
parametricObjects.append(vtk.vtkParametricEnneper())
parametricObjects.append(vtk.vtkParametricFigure8Klein())
parametricObjects.append(vtk.vtkParametricKlein())

parametricObjects.append(vtk.vtkParametricMobius())
parametricObjects[-1].SetMinimumV(-0.5)
parametricObjects[-1].SetMaximumV(0.5)
parametricObjects.append(vtk.vtkParametricRandomHills())
parametricObjects[-1].AllowRandomGenerationOff()
parametricObjects.append(vtk.vtkParametricRoman())
parametricObjects.append(vtk.vtkParametricSuperEllipsoid())
parametricObjects[-1].SetN1(0.5)
parametricObjects[-1].SetN2(0.1)

parametricObjects.append(vtk.vtkParametricSuperToroid())
parametricObjects[-1].SetN1(0.2)
parametricObjects[-1].SetN2(3.0)
parametricObjects.append(vtk.vtkParametricTorus())
parametricObjects.append(vtk.vtkParametricSpline())
# Add some points to the parametric spline.
inputPoints = vtk.vtkPoints()
vtk.vtkMath.RandomSeed(8775070)
for i in range(10):
x = vtk.vtkMath.Random(0.0,1.0)
y = vtk.vtkMath.Random(0.0,1.0)
z = vtk.vtkMath.Random(0.0,1.0)
inputPoints.InsertNextPoint(x, y, z)
parametricObjects[-1].SetPoints(inputPoints)

# There are only 15 objects.
parametricFunctionSources = list()
renderers = list()
mappers = list()
actors = list()
textmappers = list()
textactors = list()

# Create a common text property.
textProperty = vtk.vtkTextProperty()
textProperty.SetFontSize(10)
textProperty.SetJustificationToCentered()

# Create a parametric function source, renderer, mapper
# and actor for each object.
for idx, item in enumerate(parametricObjects):
parametricFunctionSources.append(vtk.vtkParametricFunctionSource())
parametricFunctionSources[idx].SetParametricFunction(item)
parametricFunctionSources[idx].Update()

mappers.append(vtk.vtkPolyDataMapper())
mappers[idx].SetInputConnection(parametricFunctionSources[idx].GetOutputPort())

actors.append(vtk.vtkActor())
actors[idx].SetMapper(mappers[idx])

textmappers.append(vtk.vtkTextMapper())
textmappers[idx].SetInput(item.GetClassName())
textmappers[idx].SetTextProperty(textProperty)

textactors.append(vtk.vtkActor2D())
textactors[idx].SetMapper(textmappers[idx])
textactors[idx].SetPosition(100, 16)

renderers.append(vtk.vtkRenderer())

gridDimensions = 4

for idx in range(len(parametricObjects)):
if idx < gridDimensions * gridDimensions:
renderers.append(vtk.vtkRenderer)

rendererSize = 200

# Create the RenderWindow
#
renderWindow = vtk.vtkRenderWindow()
renderWindow.SetSize(rendererSize * gridDimensions, rendererSize * gridDimensions)

# Add and position the renders to the render window.
viewport = list()
for row in range(gridDimensions):
for col in range(gridDimensions):
idx = row * gridDimensions + col

viewport[:] = []
viewport.append(float(col) * rendererSize / (gridDimensions * rendererSize))
viewport.append(float(gridDimensions - (row+1)) * rendererSize / (gridDimensions * rendererSize))
viewport.append(float(col+1)*rendererSize / (gridDimensions * rendererSize))
viewport.append(float(gridDimensions - row) * rendererSize / (gridDimensions * rendererSize))

if idx > (len(parametricObjects) - 1):
continue

renderers[idx].SetViewport(viewport)

renderers[idx].SetBackground(0.2,0.3,0.4)
renderers[idx].ResetCamera()
renderers[idx].GetActiveCamera().Azimuth(30)
renderers[idx].GetActiveCamera().Elevation(-30)
renderers[idx].GetActiveCamera().Zoom(0.9)
renderers[idx].ResetCameraClippingRange()

interactor = vtk.vtkRenderWindowInteractor()
interactor.SetRenderWindow(renderWindow)

renderWindow.Render()

interactor.Start()

if __name__ == "__main__":
po = ParametricObjects()
po.ParametricObjects()
```