BackgroundImage
VTKExamples/Python//BackgroundImage
Description
This example displays an image as the "background" of a scene, and renders a superquadric in front of it.
The example accepts a jpeg file on the command line to use as a background image. If there is no file, it generates a simple background.
Code
BackgroundImage.py
#!/usr/bin/env python
"""
based on:
- http://www.vtk.org/Wiki/VTK/Examples/Cxx/Images/BackgroundImage
tested with:
- VTK 6.3, Python 2.7
- VTK 7.0, Python 3.5
>>> python background_image.py image_filename.jpg
"""
from __future__ import print_function
import sys
from vtk import (
vtkJPEGReader, vtkImageCanvasSource2D, vtkImageActor, vtkPolyDataMapper,
vtkRenderer, vtkRenderWindow, vtkRenderWindowInteractor, vtkSuperquadricSource,
vtkActor, VTK_MAJOR_VERSION
)
def main(argv):
# Verify input arguments
if len(argv) > 1:
# Read the image
jpeg_reader = vtkJPEGReader()
if not jpeg_reader.CanReadFile(argv[1]):
print("Error reading file %s" % argv[1])
return
jpeg_reader.SetFileName(argv[1])
jpeg_reader.Update()
image_data = jpeg_reader.GetOutput()
else:
canvas_source = vtkImageCanvasSource2D()
canvas_source.SetExtent(0, 100, 0, 100, 0, 0)
canvas_source.SetScalarTypeToUnsignedChar()
canvas_source.SetNumberOfScalarComponents(3)
canvas_source.SetDrawColor(127, 127, 100)
canvas_source.FillBox(0, 100, 0, 100)
canvas_source.SetDrawColor(100, 255, 255)
canvas_source.FillTriangle(10, 10, 25, 10, 25, 25)
canvas_source.SetDrawColor(255, 100, 255)
canvas_source.FillTube(75, 75, 0, 75, 5.0)
canvas_source.Update()
image_data = canvas_source.GetOutput()
# Create an image actor to display the image
image_actor = vtkImageActor()
if VTK_MAJOR_VERSION <= 5:
image_actor.SetInput(image_data)
else:
image_actor.SetInputData(image_data)
# Create a renderer to display the image in the background
background_renderer = vtkRenderer()
# Create a superquadric
superquadric_source = vtkSuperquadricSource()
superquadric_source.SetPhiRoundness(1.1)
superquadric_source.SetThetaRoundness(.2)
# Create a mapper and actor
superquadric_mapper = vtkPolyDataMapper()
superquadric_mapper.SetInputConnection(superquadric_source.GetOutputPort())
superquadric_actor = vtkActor()
superquadric_actor.SetMapper(superquadric_mapper)
scene_renderer = vtkRenderer()
render_window = vtkRenderWindow()
# Set up the render window and renderers such that there is
# a background layer and a foreground layer
background_renderer.SetLayer(0)
background_renderer.InteractiveOff()
scene_renderer.SetLayer(1)
render_window.SetNumberOfLayers(2)
render_window.AddRenderer(background_renderer)
render_window.AddRenderer(scene_renderer)
render_window_interactor = vtkRenderWindowInteractor()
render_window_interactor.SetRenderWindow(render_window)
# Add actors to the renderers
scene_renderer.AddActor(superquadric_actor)
background_renderer.AddActor(image_actor)
# Render once to figure out where the background camera will be
render_window.Render()
# Set up the background camera to fill the renderer with the image
origin = image_data.GetOrigin()
spacing = image_data.GetSpacing()
extent = image_data.GetExtent()
camera = background_renderer.GetActiveCamera()
camera.ParallelProjectionOn()
xc = origin[0] + 0.5*(extent[0] + extent[1]) * spacing[0]
yc = origin[1] + 0.5*(extent[2] + extent[3]) * spacing[1]
# xd = (extent[1] - extent[0] + 1) * spacing[0]
yd = (extent[3] - extent[2] + 1) * spacing[1]
d = camera.GetDistance()
camera.SetParallelScale(0.5 * yd)
camera.SetFocalPoint(xc, yc, 0.0)
camera.SetPosition(xc, yc, d)
# Render again to set the correct view
render_window.Render()
# Interact with the window
render_window_interactor.Start()
if __name__ == '__main__':
main(sys.argv)