Polygon

VTKExamples/Python/GeometricObjects/Polygon


Description

The polygon is a primary two-dimensional cell. The polygon is defined by an ordered list of three or more points lying in a plane. The polygon normal is implicitly defined by a counterclockwise ordering of its points using the right-hand rule.

The polygon may be nonconvex, but may not have internal loops, and it cannot self-intersect. The polygon has n edges, where n is the number of points in the polygon.

Code

Polygon.py

#!/usr/bin/env python

import vtk

def main():
    colors = vtk.vtkNamedColors()

    # Setup four points
    points = vtk.vtkPoints()
    points.InsertNextPoint(0.0, 0.0, 0.0)
    points.InsertNextPoint(1.0, 0.0, 0.0)
    points.InsertNextPoint(1.0, 1.0, 0.0)
    points.InsertNextPoint(0.0, 1.0, 0.0)

    # Create the polygon
    polygon = vtk.vtkPolygon()
    polygon.GetPointIds().SetNumberOfIds(4)  # make a quad
    polygon.GetPointIds().SetId(0, 0)
    polygon.GetPointIds().SetId(1, 1)
    polygon.GetPointIds().SetId(2, 2)
    polygon.GetPointIds().SetId(3, 3)

    # Add the polygon to a list of polygons
    polygons = vtk.vtkCellArray()
    polygons.InsertNextCell(polygon)

    # Create a PolyData
    polygonPolyData = vtk.vtkPolyData()
    polygonPolyData.SetPoints(points)
    polygonPolyData.SetPolys(polygons)

    # Create a mapper and actor
    mapper = vtk.vtkPolyDataMapper()
    if vtk.VTK_MAJOR_VERSION <= 5:
        mapper.SetInput(polygonPolyData)
    else:
        mapper.SetInputData(polygonPolyData)

    actor = vtk.vtkActor()
    actor.SetMapper(mapper)
    actor.GetProperty().SetColor(colors.GetColor3d("Silver"))

    # Visualize
    renderer = vtk.vtkRenderer()
    renderWindow = vtk.vtkRenderWindow()
    renderWindow.SetWindowName("Polygon")
    renderWindow.AddRenderer(renderer)
    renderWindowInteractor = vtk.vtkRenderWindowInteractor()
    renderWindowInteractor.SetRenderWindow(renderWindow)

    renderer.AddActor(actor)
    renderer.SetBackground(colors.GetColor3d("Salmon"))
    renderWindow.Render()
    renderWindowInteractor.Start()


if __name__ == '__main__':
    main()