diff --git a/src/Cxx.md b/src/Cxx.md
index 4fd5234af374445477f9789896946bf4e5caf912..3a9d28a6b7ef37bbfa9374a8c370457732ae8e4c 100644
--- a/src/Cxx.md
+++ b/src/Cxx.md
@@ -783,6 +783,7 @@ This section includes vtkImageData vtkStructuredGrid and vtkRectilinearGrid.
[Rainbow](/Cxx/Rendering/Rainbow)| vtkLookupTable | Use and manipulation of vtkLookupTables.
[SpecularSpheres](/Cxx/Rendering/SpecularSpheres)| vtkProperty |Demonstrates the effect of specular lighting on spheres.
[StippledLine](/Cxx/Rendering/StippledLine)| vtkTexture | Draw a stippled line.
+[WalkCow](/Cxx/Rendering/WalkCow) | vtkBYUReader renWin::EraseOff() vtkActor | This generates Figs. 3-31, 3-32, 3-33 found in VTKTextbook.pdf.
## Lighting
diff --git a/src/Cxx/Rendering/CMakeLists.txt b/src/Cxx/Rendering/CMakeLists.txt
index c9e9d4226635ba33191d6fc7a25a953c6f45cf22..59f5694c81538a50390dfabe1deb8cd5342648ec 100644
--- a/src/Cxx/Rendering/CMakeLists.txt
+++ b/src/Cxx/Rendering/CMakeLists.txt
@@ -29,6 +29,7 @@ SET(KIT Rendering)
SET(NEEDS_ARGS
Rainbow
Rotations
+ WalkCow
)
SET(DATA ${WikiExamples_SOURCE_DIR}/src/Testing/Data)
SET(TEMP ${WikiExamples_BINARY_DIR}/Testing/Temporary)
@@ -39,6 +40,9 @@ ADD_TEST(${KIT}-Rotations ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${KIT}CxxTests
ADD_TEST(${KIT}-Rainbow ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${KIT}CxxTests
TestRainbow ${DATA}/combxyz.bin ${DATA}/combq.bin)
+ADD_TEST(${KIT}-WalkCow ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${KIT}CxxTests
+ TestWalkCow ${DATA}/cow.g)
+
INCLUDE(${WikiExamples_SOURCE_DIR}/CMake/ExamplesTesting.cmake)
endif()
diff --git a/src/Cxx/Rendering/WalkCow.cxx b/src/Cxx/Rendering/WalkCow.cxx
new file mode 100644
index 0000000000000000000000000000000000000000..09e35a43e7300e6a8f8f84b1dab42ef31f10b4d7
--- /dev/null
+++ b/src/Cxx/Rendering/WalkCow.cxx
@@ -0,0 +1,480 @@
+// Translated from walkCow.tcl
+
+#include <vtkActor.h>
+#include <vtkAxes.h>
+#include <vtkBYUReader.h>
+#include <vtkCallbackCommand.h>
+#include <vtkCamera.h>
+#include <vtkNamedColors.h>
+#include <vtkPNGWriter.h>
+#include <vtkPolyDataMapper.h>
+#include <vtkProperty.h>
+#include <vtkRenderWindow.h>
+#include <vtkRenderWindowInteractor.h>
+#include <vtkRenderer.h>
+#include <vtkSmartPointer.h>
+#include <vtkTransform.h>
+#include <vtkWindowToImageFilter.h>
+
+#include <algorithm>
+#include <vector>
+
+namespace
+{
+/*
+These Rotate* and Walk functions create a scene where multiple
+ views of the object exist.
+
+ They all operate in a similar manner, namely:
+ 1) Accept vtkActor, vtkRenderer, vtkRenderWindow as parameters.
+ 2) Position the object.
+ 3) Position the observer with the focal point sent to the centre
+ of the object.
+ 4) Render and set EraseOff() in the render window.
+ Note that:
+ EraseOff() has to be called after a Render() call
+ to work in the desired way.
+ 5) Then rotate or walk the object around the scene.
+ 6) Write out the scene using Screenshot().
+ 6) Set EraseOff() in the render window.
+ 7) Reset the object position.
+
+*/
+void Rotate_X(vtkActor* cowActor, vtkRenderer* ren, vtkRenderWindow* renWin);
+void Rotate_Y(vtkActor* cowActor, vtkRenderer* ren, vtkRenderWindow* renWin);
+void Rotate_Z(vtkActor* cowActor, vtkRenderer* ren, vtkRenderWindow* renWin);
+void Rotate_XY(vtkActor* cowActor, vtkRenderer* ren, vtkRenderWindow* renWin);
+void Rotate_V_0(vtkActor* cowActor, vtkRenderer* ren, vtkRenderWindow* renWin);
+void Rotate_V_V(vtkActor* cowActor, vtkRenderer* ren, vtkRenderWindow* renWin);
+void Walk(vtkActor* cowActor, vtkRenderer* ren, vtkRenderWindow* renWin);
+
+/*
+// Used to estimate positions similar to the book illustrations.
+static void CameraModifiedCallback(vtkObject* caller,
+ long unsigned int vtkNotUsed(eventId),
+ void* vtkNotUsed(clientData),
+ void* vtkNotUsed(callData));
+*/
+
+// Save a screenshot.
+void Screenshot(std::string fileName, vtkRenderWindow* renWin);
+}
+
+int main(int argc, char* argv[])
+{
+ auto Scale = [](std::vector<double>& v, double scale) {
+ std::transform(std::begin(v), std::end(v), std::begin(v),
+ [=](double const& n) { return n / scale; });
+ return;
+ };
+
+ if (argc != 2)
+ {
+ std::cout << "usage: ./WalkCow filename" << std::endl;
+ std::cout << "where: filename is the file cow.g" << std::endl;
+ return EXIT_FAILURE;
+ }
+
+ std::string fileName = argv[1];
+ vtkSmartPointer<vtkNamedColors> colors =
+ vtkSmartPointer<vtkNamedColors>::New();
+ // Set the background color. Match those in VTKTextbook.pdf.
+ auto scale = 256.0;
+ std::vector<double> bkg1 = {60, 93, 144};
+ std::vector<double> bkg2 = {25, 51, 102};
+ Scale(bkg1, scale);
+ colors->SetColor("BkgColor1", bkg1[0], bkg1[1], bkg1[2]);
+ Scale(bkg2, scale);
+ colors->SetColor("BkgColor2", bkg2[0], bkg2[1], bkg2[2]);
+
+ vtkSmartPointer<vtkRenderer> ren = vtkSmartPointer<vtkRenderer>::New();
+ vtkSmartPointer<vtkRenderWindow> renWin =
+ vtkSmartPointer<vtkRenderWindow>::New();
+ renWin->AddRenderer(ren);
+
+ vtkSmartPointer<vtkRenderWindowInteractor> iren =
+ vtkSmartPointer<vtkRenderWindowInteractor>::New();
+ iren->SetRenderWindow(renWin);
+
+ // The cow pipeline.
+ vtkSmartPointer<vtkBYUReader> cow = vtkSmartPointer<vtkBYUReader>::New();
+ cow->SetGeometryFileName(fileName.c_str());
+ cow->Update();
+
+ vtkSmartPointer<vtkPolyDataMapper> cowMapper =
+ vtkSmartPointer<vtkPolyDataMapper>::New();
+ cowMapper->SetInputConnection(cow->GetOutputPort());
+ cowMapper->ScalarVisibilityOff();
+
+ vtkSmartPointer<vtkActor> cowActor = vtkSmartPointer<vtkActor>::New();
+ cowActor->SetMapper(cowMapper);
+ cowActor->GetProperty()->SetColor(colors->GetColor3d("Wheat").GetData());
+
+ ren->AddActor(cowActor);
+
+ // Axes pipeline.
+ vtkSmartPointer<vtkAxes> cowAxesSource = vtkSmartPointer<vtkAxes>::New();
+ cowAxesSource->SetScaleFactor(10.0);
+ cowAxesSource->SetOrigin(0, 0, 0);
+
+ vtkSmartPointer<vtkPolyDataMapper> cowAxesMapper =
+ vtkSmartPointer<vtkPolyDataMapper>::New();
+ cowAxesMapper->SetInputConnection(cowAxesSource->GetOutputPort());
+
+ vtkSmartPointer<vtkActor> cowAxes = vtkSmartPointer<vtkActor>::New();
+ cowAxes->SetMapper(cowAxesMapper);
+ cowAxes->VisibilityOff();
+
+ ren->AddActor(cowAxes);
+
+ ren->SetBackground(colors->GetColor3d("BkgColor1").GetData());
+ renWin->SetSize(600, 480);
+
+ iren->Initialize();
+ cowAxes->VisibilityOn();
+ renWin->Render();
+
+ // Activate this if you want to see the Position and Focal point.
+ // vtkSmartPointer<vtkCallbackCommand> modifiedCallback =
+ // vtkSmartPointer<vtkCallbackCommand>::New();
+ // modifiedCallback->SetCallback(CameraModifiedCallback);
+ // ren->GetActiveCamera()->AddObserver(vtkCommand::ModifiedEvent,
+ // modifiedCallback);
+
+ // These four rotations use the same camera position.
+ Rotate_X(cowActor, ren, renWin);
+ Rotate_Y(cowActor, ren, renWin);
+ Rotate_Z(cowActor, ren, renWin);
+ Rotate_XY(cowActor, ren, renWin);
+
+ ren->SetBackground(colors->GetColor3d("BkgColor2").GetData());
+ Rotate_V_0(cowActor, ren, renWin);
+ Rotate_V_V(cowActor, ren, renWin);
+ // Walk() needs to go after Rotate_V_0() or Rotate_V_V().
+ Walk(cowActor, ren, renWin);
+
+ // Interact with data.
+ // Keep the last rendered image.
+ renWin->EraseOff();
+ iren->Start();
+ return EXIT_SUCCESS;
+}
+
+namespace
+{
+
+void Rotate_X(vtkActor* cowActor, vtkRenderer* ren, vtkRenderWindow* renWin)
+{
+ // Six rotations about the x axis.
+ ren->ResetCamera();
+ ren->ResetCameraClippingRange();
+ cowActor->SetOrientation(0.0, 0.0, 0.0);
+ cowActor->SetOrigin(0.0, 0.0, 0);
+ cowActor->SetPosition(0, 0, 0);
+ // Get the focal point.
+ double* bounds = cowActor->GetBounds();
+ double fp[3];
+ for (int i = 0; i < 3; ++i)
+ {
+ fp[i] = (bounds[i * 2 + 1] + bounds[i * 2]) / 2.0;
+ }
+ // This closely matches the original illustration.
+ ren->GetActiveCamera()->SetPosition(2, 25, 0);
+ ren->GetActiveCamera()->SetFocalPoint(fp);
+ ren->GetActiveCamera()->SetViewUp(0, 0, -1);
+ ren->ResetCameraClippingRange();
+ renWin->Render();
+ renWin->Render();
+ renWin->EraseOff();
+ for (int idx = 0; idx < 6; idx++)
+ {
+ cowActor->RotateX(60);
+ renWin->Render();
+ renWin->Render();
+ }
+ Screenshot("Fig3-31a.png", renWin);
+ renWin->EraseOn();
+}
+
+void Rotate_Y(vtkActor* cowActor, vtkRenderer* ren, vtkRenderWindow* renWin)
+{
+ // Six rotations about the y axis.
+ ren->ResetCamera();
+ ren->ResetCameraClippingRange();
+ cowActor->SetOrientation(0.0, 0.0, 0.0);
+ cowActor->SetOrigin(0.0, 0.0, 0);
+ cowActor->SetPosition(0, 0, 0);
+ // Get the focal point.
+ double* bounds = cowActor->GetBounds();
+ double fp[3];
+ for (int i = 0; i < 3; ++i)
+ {
+ fp[i] = (bounds[i * 2 + 1] + bounds[i * 2]) / 2.0;
+ }
+ // This closely matches the original illustration.
+ ren->GetActiveCamera()->SetPosition(2, 0, 25);
+ ren->GetActiveCamera()->SetFocalPoint(fp);
+ ren->GetActiveCamera()->SetViewUp(0, 1, 0);
+ ren->ResetCameraClippingRange();
+ renWin->Render();
+ renWin->Render();
+ renWin->EraseOff();
+ for (int idx = 0; idx < 6; idx++)
+ {
+ cowActor->RotateY(60);
+ renWin->Render();
+ renWin->Render();
+ }
+ Screenshot("Fig3-31b.png", renWin);
+ renWin->EraseOn();
+}
+
+void Rotate_Z(vtkActor* cowActor, vtkRenderer* ren, vtkRenderWindow* renWin)
+{
+ // Six rotations about the z axis.
+ ren->ResetCamera();
+ ren->ResetCameraClippingRange();
+ cowActor->SetOrientation(0.0, 0.0, 0.0);
+ cowActor->SetOrigin(0.0, 0.0, 0);
+ cowActor->SetPosition(0, 0, 0);
+ // Get the focal point.
+ double* bounds = cowActor->GetBounds();
+ double fp[3];
+ for (int i = 0; i < 3; ++i)
+ {
+ fp[i] = (bounds[i * 2 + 1] + bounds[i * 2]) / 2.0;
+ }
+ // This closely matches the original illustration.
+ ren->GetActiveCamera()->SetPosition(2, 0, 25);
+ ren->GetActiveCamera()->SetFocalPoint(fp);
+ ren->GetActiveCamera()->SetViewUp(0, 1, 0);
+ ren->ResetCameraClippingRange();
+ renWin->Render();
+ renWin->Render();
+ renWin->EraseOff();
+ for (int idx = 0; idx < 6; idx++)
+ {
+ cowActor->RotateZ(60);
+ renWin->Render();
+ renWin->Render();
+ }
+ Screenshot("Fig3-31c.png", renWin);
+ renWin->EraseOn();
+}
+
+void Rotate_XY(vtkActor* cowActor, vtkRenderer* ren, vtkRenderWindow* renWin)
+{
+ // First a rotation about the x axis, then six rotations about the y axis.
+ ren->ResetCamera();
+ ren->ResetCameraClippingRange();
+ cowActor->SetOrientation(0.0, 0.0, 0.0);
+ cowActor->SetOrigin(0.0, 0.0, 0);
+ cowActor->SetPosition(0, 0, 0);
+ // Get the focal point.
+ double* bounds = cowActor->GetBounds();
+ double fp[3];
+ for (int i = 0; i < 3; ++i)
+ {
+ fp[i] = (bounds[i * 2 + 1] + bounds[i * 2]) / 2.0;
+ }
+ // This closely matches the original illustration.
+ ren->GetActiveCamera()->SetPosition(2, 0, 25);
+ ren->GetActiveCamera()->SetFocalPoint(fp);
+ ren->GetActiveCamera()->SetViewUp(0, 1, 0);
+ ren->ResetCameraClippingRange();
+ renWin->Render();
+ renWin->Render();
+ renWin->EraseOff();
+ cowActor->RotateX(60);
+ for (int idx = 0; idx < 6; idx++)
+ {
+ cowActor->RotateY(60);
+ renWin->Render();
+ renWin->Render();
+ }
+ cowActor->RotateX(-60);
+ Screenshot("Fig3-31d.png", renWin);
+ renWin->EraseOn();
+}
+
+void Rotate_V_0(vtkActor* cowActor, vtkRenderer* ren, vtkRenderWindow* renWin)
+{
+ // The cow rotating about a vector passing through her nose.
+ // With the origin at (0, 0, 0).
+ ren->ResetCamera();
+ ren->ResetCameraClippingRange();
+ cowActor->SetOrientation(0.0, 0.0, 0.0);
+ cowActor->SetOrigin(0.0, 0.0, 0);
+ cowActor->SetPosition(0, 0, 0);
+ // Get the focal point.
+ double* bounds = cowActor->GetBounds();
+ double fp[3];
+ for (int i = 0; i < 3; ++i)
+ {
+ fp[i] = (bounds[i * 2 + 1] + bounds[i * 2]) / 2.0;
+ }
+ vtkSmartPointer<vtkTransform> cowPos = vtkSmartPointer<vtkTransform>::New();
+ cowPos->Identity();
+ cowPos->SetMatrix(cowActor->GetMatrix());
+ vtkSmartPointer<vtkTransform> cowTransform =
+ vtkSmartPointer<vtkTransform>::New();
+ cowTransform->Identity();
+ cowActor->SetUserMatrix(cowTransform->GetMatrix());
+ // This closely matches the original illustration.
+ ren->GetActiveCamera()->SetPosition(16, 9, -12);
+ ren->GetActiveCamera()->SetFocalPoint(fp);
+ ren->ResetCameraClippingRange();
+ renWin->Render();
+ renWin->Render();
+ renWin->EraseOff();
+ for (int idx = 0; idx < 6; idx++)
+ {
+ cowActor->RotateWXYZ(60, 2.19574, -1.42455, -0.0331036);
+ renWin->Render();
+ renWin->Render();
+ }
+ Screenshot("Fig3-33a.png", renWin);
+ renWin->EraseOn();
+ // Put the cow back on the origin.
+ for (int idx = 0; idx < 6; idx++)
+ {
+ cowActor->RotateWXYZ(-60, 2.19574, -1.42455, -0.0331036);
+ }
+ cowActor->SetUserMatrix(cowPos->GetMatrix());
+ ren->GetActiveCamera()->SetPosition(0, 0, 1);
+ ren->GetActiveCamera()->SetViewUp(0, 1, 0);
+ ren->ResetCamera();
+}
+
+void Rotate_V_V(vtkActor* cowActor, vtkRenderer* ren, vtkRenderWindow* renWin)
+{
+ // The cow rotating about a vector passing through her nose.
+ // With the origin at (6.11414, 1.27386, 0.015175).
+ ren->ResetCamera();
+ ren->ResetCameraClippingRange();
+ cowActor->SetOrientation(0.0, 0.0, 0.0);
+ cowActor->SetOrigin(0.0, 0.0, 0);
+ cowActor->SetPosition(0, 0, 0);
+ // Get the focal point.
+ double* bounds = cowActor->GetBounds();
+ double fp[3];
+ for (int i = 0; i < 3; ++i)
+ {
+ fp[i] = (bounds[i * 2 + 1] + bounds[i * 2]) / 2.0;
+ }
+ vtkSmartPointer<vtkTransform> cowPos = vtkSmartPointer<vtkTransform>::New();
+ cowPos->Identity();
+ cowPos->SetMatrix(cowActor->GetMatrix());
+ cowActor->SetOrigin(6.11414, 1.27386, 0.015175); // The cow's nose
+ vtkSmartPointer<vtkTransform> cowTransform =
+ vtkSmartPointer<vtkTransform>::New();
+ cowTransform->Identity();
+ cowActor->SetUserMatrix(cowTransform->GetMatrix());
+ // This closely matches the original illustration.
+ ren->GetActiveCamera()->SetPosition(31, 23, -21);
+ ren->GetActiveCamera()->SetFocalPoint(fp);
+ ren->ResetCameraClippingRange();
+ renWin->Render();
+ renWin->Render();
+ renWin->EraseOff();
+ for (int idx = 0; idx < 6; idx++)
+ {
+ cowActor->RotateWXYZ(60, 2.19574, -1.42455, -0.0331036);
+ renWin->Render();
+ renWin->Render();
+ }
+ Screenshot("Fig3-33b.png", renWin);
+ renWin->EraseOn();
+ // Put the cow back on the origin.
+ for (int idx = 0; idx < 6; idx++)
+ {
+ cowActor->RotateWXYZ(-60, 2.19574, -1.42455, -0.0331036);
+ }
+ cowActor->SetUserMatrix(cowPos->GetMatrix());
+}
+
+void Walk(vtkActor* cowActor, vtkRenderer* ren, vtkRenderWindow* renWin)
+{
+ // The cow "walking" around the global origin
+ vtkSmartPointer<vtkTransform> cowPos = vtkSmartPointer<vtkTransform>::New();
+ cowPos->Identity();
+ cowPos->SetMatrix(cowActor->GetMatrix());
+ cowActor->SetOrientation(0.0, 0.0, 0.0);
+ cowActor->SetOrigin(0.0, 0.0, 0.0);
+ // Get the focal point.
+ double* bounds = cowActor->GetBounds();
+ double fp[3];
+ for (int i = 0; i < 3; ++i)
+ {
+ fp[i] = (bounds[i * 2 + 1] + bounds[i * 2]) / 2.0;
+ }
+ vtkSmartPointer<vtkTransform> cowTransform =
+ vtkSmartPointer<vtkTransform>::New();
+ cowTransform->Identity();
+ cowTransform->Translate(0, 0, 5);
+ cowActor->SetUserMatrix(cowTransform->GetMatrix());
+ // This closely matches the original illustration.
+ ren->GetActiveCamera()->SetPosition(1, 24, 16);
+ ren->GetActiveCamera()->SetFocalPoint(fp);
+ ren->GetActiveCamera()->SetViewUp(0, 0, -1);
+ ren->ResetCameraClippingRange();
+ renWin->Render();
+ renWin->Render();
+ renWin->EraseOff();
+ for (int idx = 0; idx < 6; idx++)
+ {
+ cowTransform->Identity();
+ cowTransform->RotateY(idx * 60);
+ cowTransform->Translate(0, 0, 5);
+ cowActor->SetUserMatrix(cowTransform->GetMatrix());
+ renWin->Render();
+ renWin->Render();
+ }
+ Screenshot("Fig3-32.png", renWin);
+ renWin->EraseOn();
+ // Walkies are over, put the cow back on the origin.
+ // cowActor->SetUserMatrix(cowPos->GetMatrix());
+}
+
+/*
+static void CameraModifiedCallback(vtkObject* caller,
+ long unsigned int vtkNotUsed(eventId),
+ void* vtkNotUsed(clientData),
+ void* vtkNotUsed(callData))
+{
+ std::cout << caller->GetClassName() << " modified" << std::endl;
+ vtkCamera* camera = static_cast<vtkCamera*>(caller);
+ // Print the interesting stuff.
+ std::cout << "\tPosition: " << camera->GetPosition()[0] << ", "
+ << camera->GetPosition()[1] << ", " << camera->GetPosition()[2]
+ << std::endl;
+ std::cout << "\tFocal point: " << camera->GetFocalPoint()[0] << ", "
+ << camera->GetFocalPoint()[1] << ", " << camera->GetFocalPoint()[2]
+ << std::endl;
+}
+*/
+
+void Screenshot(std::string fileName, vtkRenderWindow* renWin)
+{
+ vtkSmartPointer<vtkWindowToImageFilter> windowToImageFilter =
+ vtkSmartPointer<vtkWindowToImageFilter>::New();
+ windowToImageFilter->SetInput(renWin);
+#if VTK_MAJOR_VERSION > 8 || VTK_MAJOR_VERSION == 8 && VTK_MINOR_VERSION >= 1
+ windowToImageFilter->SetScale(1); // image quality
+#else
+ windowToImageFilter->SetMagnification(1); // image quality
+#endif
+ // We are not recording the alpha (transparency) channel.
+ // windowToImageFilter->SetInputBufferTypeToRGBA();
+ windowToImageFilter->SetInputBufferTypeToRGB();
+ // Read from the front buffer.
+ windowToImageFilter->ReadFrontBufferOff();
+ windowToImageFilter->Update();
+
+ vtkSmartPointer<vtkPNGWriter> writer = vtkSmartPointer<vtkPNGWriter>::New();
+ writer->SetFileName(fileName.c_str());
+ writer->SetInputConnection(windowToImageFilter->GetOutputPort());
+ writer->Write();
+}
+
+}
diff --git a/src/Cxx/Rendering/WalkCow.md b/src/Cxx/Rendering/WalkCow.md
new file mode 100644
index 0000000000000000000000000000000000000000..3221ab11c88b9e2bc0edfe3d1bbf5378a4294b72
--- /dev/null
+++ b/src/Cxx/Rendering/WalkCow.md
@@ -0,0 +1,2 @@
+### Description
+This generates Fig 3-31: Rotations of a cow about her axes.; Fig. 3-32: The cow "walking" around the global origin; Fig. 3-33: The cow rotating about a vector passing through her nose found in VTKTextbook.pdf.
diff --git a/src/Python.md b/src/Python.md
index a917604269f3831550771d19ba632d93e47ad2a3..732544f083cbbade4f65becd413bf910b59ffb9d 100644
--- a/src/Python.md
+++ b/src/Python.md
@@ -161,6 +161,11 @@ This section includes examples of manipulating meshes.
[Variant](/Python/Variant) | vtkVariant |
vtkVersion |
+## Rendering
+| Example Name | Classes Demonstrated | Description | Image |
+|--------------|----------------------|-------------|-------|
+[WalkCow](/Python/Rendering/WalkCow) | vtkBYUReader renWin::EraseOff() vtkActor | This generates Figs. 3-31, 3-32, 3-33 found in VTKTextbook.pdf.
+
## Visualization
| Example Name | Classes Demonstrated | Description | Image |
diff --git a/src/Python/Rendering/WalkCow.md b/src/Python/Rendering/WalkCow.md
new file mode 100644
index 0000000000000000000000000000000000000000..3221ab11c88b9e2bc0edfe3d1bbf5378a4294b72
--- /dev/null
+++ b/src/Python/Rendering/WalkCow.md
@@ -0,0 +1,2 @@
+### Description
+This generates Fig 3-31: Rotations of a cow about her axes.; Fig. 3-32: The cow "walking" around the global origin; Fig. 3-33: The cow rotating about a vector passing through her nose found in VTKTextbook.pdf.
diff --git a/src/Python/Rendering/WalkCow.py b/src/Python/Rendering/WalkCow.py
new file mode 100644
index 0000000000000000000000000000000000000000..f6b2cb6d4447cc68bcb343097be0a996209a5189
--- /dev/null
+++ b/src/Python/Rendering/WalkCow.py
@@ -0,0 +1,393 @@
+#!/usr/local/bin/python
+
+# Translated from walkCow.tcl
+
+import vtk
+
+
+def main():
+ file_name = get_program_parameters()
+
+ colors = vtk.vtkNamedColors()
+ # Set the background color. Match those in VTKTextbook.pdf.
+ bkg1 = map(lambda x: x / 256.0, [60, 93, 144])
+ bkg2 = map(lambda x: x / 256.0, [25, 51, 102])
+ colors.SetColor("BkgColor1", *bkg1)
+ colors.SetColor("BkgColor2", *bkg2)
+
+ ren = vtk.vtkRenderer()
+ renWin = vtk.vtkRenderWindow()
+ renWin.AddRenderer(ren)
+
+ iren = vtk.vtkRenderWindowInteractor()
+ iren.SetRenderWindow(renWin)
+
+ # The cow pipeline.
+ cow = vtk.vtkBYUReader()
+ cow.SetGeometryFileName(file_name)
+ cow.Update()
+
+ cowMapper = vtk.vtkPolyDataMapper()
+ cowMapper.SetInputConnection(cow.GetOutputPort())
+ cowMapper.ScalarVisibilityOff()
+
+ cowActor = vtk.vtkActor()
+ cowActor.SetMapper(cowMapper)
+ cowActor.GetProperty().SetColor(colors.GetColor3d("Wheat"))
+
+ ren.AddActor(cowActor)
+
+ # Axes pipeline.
+ cowAxesSource = vtk.vtkAxes()
+ cowAxesSource.SetScaleFactor(10.0)
+ cowAxesSource.SetOrigin(0, 0, 0)
+
+ cowAxesMapper = vtk.vtkPolyDataMapper()
+ cowAxesMapper.SetInputConnection(cowAxesSource.GetOutputPort())
+
+ cowAxes = vtk.vtkActor()
+ cowAxes.SetMapper(cowAxesMapper)
+ cowAxes.VisibilityOff()
+
+ ren.AddActor(cowAxes)
+
+ ren.SetBackground(colors.GetColor3d("BkgColor1"))
+ renWin.SetSize(600, 480)
+
+ iren.Initialize()
+ cowAxes.VisibilityOn()
+ renWin.Render()
+
+ # A general comment:
+ # EraseOff() has to be called after a Render() call to work in the desired way.
+
+ # Activate this if you want to see the Position and Focal point.
+ # ren.GetActiveCamera().AddObserver('ModifiedEvent', CameraModifiedCallback)
+
+ # These four walks use the same camera position.
+ Rotate_X(cowActor, ren, renWin)
+ Rotate_Y(cowActor, ren, renWin)
+ Rotate_Z(cowActor, ren, renWin)
+ Rotate_XY(cowActor, ren, renWin)
+
+ ren.SetBackground(colors.GetColor3d("BkgColor2"))
+ Rotate_V_0(cowActor, ren, renWin)
+ Rotate_V_V(cowActor, ren, renWin)
+ # Walk() needs to go after Rotate_V_0() or Rotate_V_V().
+ Walk(cowActor, ren, renWin)
+
+ # Interact with data.
+ renWin.EraseOff()
+ iren.Start()
+
+
+def get_program_parameters():
+ import argparse
+ description = 'Produce figures: 3-31, 3-32, 3-33 from the VTK Textbook.'
+ epilogue = '''
+ Produce figures 3-31, 3-32, 3-33 from the VTK Textbook.
+ It is a translation of the original WalkCow.tcl with a few additional enhancements.
+ '''
+ parser = argparse.ArgumentParser(description=description, epilog=epilogue)
+ parser.add_argument('filename', help='The file cow.g.')
+ args = parser.parse_args()
+ return args.filename
+
+
+"""
+ These Rotate* and Walk functions create a scene where multiple
+ views of the object exist.
+
+ They all operate in a similar manner, namely:
+ 1) Accept vtkActor, vtkRenderer, vtkRenderWindow as parameters.
+ 2) Position the object.
+ 3) Position the observer with the focal point sent to the centre
+ of the object.
+ 4) Render and set EraseOff() in the render window.
+ Note that:
+ EraseOff() has to be called after a Render() call
+ to work in the desired way.
+ 5) Then rotate or Walk the object around the scene.
+ 6) Write out the scene using Screenshot().
+ 6) Set EraseOff() in the render window.
+ 7) Reset the object position.
+
+"""
+
+
+def Rotate_X(cowActor, ren, renWin):
+ # Six rotations about the x axis.
+ ren.ResetCamera()
+ ren.ResetCameraClippingRange()
+ cowActor.SetOrientation(0.0, 0.0, 0.0)
+ cowActor.SetOrigin(0.0, 0.0, 0)
+ cowActor.SetPosition(0, 0, 0)
+ # Get the focal point.
+ bounds = cowActor.GetBounds()
+ fp = [0.0] * 3
+ for i in range(0, 3):
+ fp[i] = (bounds[i * 2 + 1] + bounds[i * 2]) / 2.0
+ # This closely matches the original illustration.
+ ren.GetActiveCamera().SetPosition(2, 25, 0)
+ ren.GetActiveCamera().SetFocalPoint(fp)
+ ren.GetActiveCamera().SetViewUp(0, 0, -1)
+ ren.ResetCameraClippingRange()
+ renWin.Render()
+ renWin.Render()
+ renWin.EraseOff()
+ for idx in range(0, 6):
+ cowActor.RotateX(60)
+ renWin.Render()
+ renWin.Render()
+ Screenshot("Fig3-31a.png", renWin)
+ renWin.EraseOn()
+
+
+def Rotate_Y(cowActor, ren, renWin):
+ # Six rotations about the y axis.
+ ren.ResetCamera()
+ ren.ResetCameraClippingRange()
+ cowActor.SetOrientation(0.0, 0.0, 0.0)
+ cowActor.SetOrigin(0.0, 0.0, 0)
+ cowActor.SetPosition(0, 0, 0)
+ # Get the focal point.
+ bounds = cowActor.GetBounds()
+ fp = [0.0] * 3
+ for i in range(0, 3):
+ fp[i] = (bounds[i * 2 + 1] + bounds[i * 2]) / 2.0
+ # This closely matches the original illustration.
+ ren.GetActiveCamera().SetPosition(2, 0, 25)
+ ren.GetActiveCamera().SetFocalPoint(fp)
+ ren.GetActiveCamera().SetViewUp(0, 1, 0)
+ ren.ResetCameraClippingRange()
+ renWin.Render()
+ renWin.Render()
+ renWin.EraseOff()
+ for idx in range(0, 6):
+ cowActor.RotateY(60)
+ renWin.Render()
+ renWin.Render()
+ Screenshot("Fig3-31b.png", renWin)
+ renWin.EraseOn()
+
+
+def Rotate_Z(cowActor, ren, renWin):
+ # Six rotations about the z axis.
+ ren.ResetCamera()
+ ren.ResetCameraClippingRange()
+ cowActor.SetOrientation(0.0, 0.0, 0.0)
+ cowActor.SetOrigin(0.0, 0.0, 0)
+ cowActor.SetPosition(0, 0, 0)
+ # Get the focal point.
+ bounds = cowActor.GetBounds()
+ fp = [0.0] * 3
+ for i in range(0, 3):
+ fp[i] = (bounds[i * 2 + 1] + bounds[i * 2]) / 2.0
+ # This closely matches the original illustration.
+ # ren.GetActiveCamera().SetPosition(2, 0, 25)
+ ren.GetActiveCamera().SetPosition(2, 0, 25)
+ ren.GetActiveCamera().SetFocalPoint(fp)
+ ren.GetActiveCamera().SetViewUp(0, 1, 0)
+ ren.ResetCameraClippingRange()
+ renWin.Render()
+ renWin.Render()
+ renWin.EraseOff()
+ for idx in range(0, 6):
+ cowActor.RotateZ(60)
+ renWin.Render()
+ renWin.Render()
+ Screenshot("Fig3-31c.png", renWin)
+ renWin.EraseOn()
+
+
+def Rotate_XY(cowActor, ren, renWin):
+ # First a rotation about the x axis, then six rotations about the y axis.
+ ren.ResetCamera()
+ ren.ResetCameraClippingRange()
+ cowActor.SetOrientation(0.0, 0.0, 0.0)
+ cowActor.SetOrigin(0.0, 0.0, 0)
+ cowActor.SetPosition(0, 0, 0)
+ # Get the focal point.
+ bounds = cowActor.GetBounds()
+ fp = [0.0] * 3
+ for i in range(0, 3):
+ fp[i] = (bounds[i * 2 + 1] + bounds[i * 2]) / 2.0
+ # This closely matches the original illustration.
+ # ren.GetActiveCamera().SetPosition(2, 0, 24)
+ ren.GetActiveCamera().SetPosition(2, 0, 25)
+ ren.GetActiveCamera().SetFocalPoint(fp)
+ ren.GetActiveCamera().SetViewUp(0, 1, 0)
+ ren.ResetCameraClippingRange()
+ renWin.Render()
+ renWin.Render()
+ renWin.EraseOff()
+ cowActor.RotateX(60)
+ for idx in range(0, 6):
+ cowActor.RotateY(60)
+ renWin.Render()
+ renWin.Render()
+ cowActor.RotateX(-60)
+ Screenshot("Fig3-31d.png", renWin)
+ renWin.EraseOn()
+
+
+def Rotate_V_0(cowActor, ren, renWin):
+ # The cow rotating about a vector passing through her nose.
+ # With the origin at (0, 0, 0).
+ ren.ResetCamera()
+ ren.ResetCameraClippingRange()
+ cowActor.SetOrientation(0.0, 0.0, 0.0)
+ cowActor.SetOrigin(0.0, 0.0, 0)
+ cowActor.SetPosition(0, 0, 0)
+ # Get the focal point.
+ bounds = cowActor.GetBounds()
+ fp = [0.0] * 3
+ for i in range(0, 3):
+ fp[i] = (bounds[i * 2 + 1] + bounds[i * 2]) / 2.0
+ cowPos = vtk.vtkTransform()
+ cowPos.Identity()
+ cowPos.SetMatrix(cowActor.GetMatrix())
+ cowTransform = vtk.vtkTransform()
+ cowTransform.Identity()
+ cowActor.SetUserMatrix(cowTransform.GetMatrix())
+ # This closely matches the original illustration.
+ ren.GetActiveCamera().SetPosition(16, 9, -12)
+ ren.GetActiveCamera().SetFocalPoint(fp)
+ ren.ResetCameraClippingRange()
+ renWin.Render()
+ renWin.Render()
+ renWin.EraseOff()
+ for idx in range(0, 6):
+ cowActor.RotateWXYZ(60, 2.19574, -1.42455, -0.0331036)
+ renWin.Render()
+ renWin.Render()
+ Screenshot("Fig3-33a.png", renWin)
+ renWin.EraseOn()
+ # Put the cow back on the origin.
+ for idx in range(0, 6):
+ cowActor.RotateWXYZ(-60, 2.19574, -1.42455, -0.0331036)
+ cowActor.SetUserMatrix(cowPos.GetMatrix())
+ ren.GetActiveCamera().SetPosition(0, 0, 1)
+ ren.GetActiveCamera().SetViewUp(0, 1, 0)
+ ren.ResetCamera()
+
+
+def Rotate_V_V(cowActor, ren, renWin):
+ # The cow rotating about a vector passing through her nose.
+ # With the origin at (6.11414, 1.27386, 0.015175).
+ ren.ResetCamera()
+ ren.ResetCameraClippingRange()
+ cowActor.SetOrientation(0.0, 0.0, 0.0)
+ cowActor.SetOrigin(0.0, 0.0, 0)
+ cowActor.SetPosition(0, 0, 0)
+ # Get the focal point.
+ bounds = cowActor.GetBounds()
+ fp = [0.0] * 3
+ for i in range(0, 3):
+ fp[i] = (bounds[i * 2 + 1] + bounds[i * 2]) / 2.0
+ cowPos = vtk.vtkTransform()
+ cowPos.Identity()
+ cowPos.SetMatrix(cowActor.GetMatrix())
+ cowActor.SetOrigin(6.11414, 1.27386, 0.015175) # The cow's nose
+ cowTransform = vtk.vtkTransform()
+ cowTransform.Identity()
+ cowActor.SetUserMatrix(cowTransform.GetMatrix())
+ # This closely matches the original illustration.
+ ren.GetActiveCamera().SetPosition(31, 23, -21)
+ ren.GetActiveCamera().SetFocalPoint(fp)
+ ren.ResetCameraClippingRange()
+ renWin.Render()
+ renWin.Render()
+ renWin.EraseOff()
+ for idx in range(0, 6):
+ cowActor.RotateWXYZ(60, 2.19574, -1.42455, -0.0331036)
+ renWin.Render()
+ renWin.Render()
+ Screenshot("Fig3-33b.png", renWin)
+ renWin.EraseOn()
+ # Put the cow back on the origin.
+ for idx in range(0, 6):
+ cowActor.RotateWXYZ(-60, 2.19574, -1.42455, -0.0331036)
+ cowActor.SetUserMatrix(cowPos.GetMatrix())
+
+
+def Walk(cowActor, ren, renWin):
+ # The cow "walking" around the global origin
+ cowPos = vtk.vtkTransform()
+ cowPos.Identity()
+ cowPos.SetMatrix(cowActor.GetMatrix())
+ cowActor.SetOrientation(0.0, 0.0, 0.0)
+ cowActor.SetOrigin(0.0, 0.0, 0.0)
+ # Get the focal point.
+ bounds = cowActor.GetBounds()
+ fp = [0.0] * 3
+ for i in range(0, 3):
+ fp[i] = (bounds[i * 2 + 1] + bounds[i * 2]) / 2.0
+ cowTransform = vtk.vtkTransform()
+ cowTransform.Identity()
+ cowTransform.Translate(0, 0, 5)
+ cowActor.SetUserMatrix(cowTransform.GetMatrix())
+ # This closely matches the original illustration.
+ ren.GetActiveCamera().SetPosition(1, 24, 16)
+ ren.GetActiveCamera().SetFocalPoint(fp)
+ ren.GetActiveCamera().SetViewUp(0, 0, -1)
+ ren.ResetCameraClippingRange()
+ renWin.Render()
+ renWin.Render()
+ renWin.EraseOff()
+ for idx in range(1, 7):
+ cowTransform.Identity()
+ cowTransform.RotateY(idx * 60)
+ cowTransform.Translate(0, 0, 5)
+ cowActor.SetUserMatrix(cowTransform.GetMatrix())
+ renWin.Render()
+ renWin.Render()
+ Screenshot("Fig3-32.png", renWin)
+ renWin.EraseOn()
+ # Walkies are over, put the cow back on the origin.
+ # cowActor.SetUserMatrix(cowPos.GetMatrix())
+
+
+def CameraModifiedCallback(caller):
+ """
+ Used to estimate positions similar to the book illustrations.
+ :param caller:
+ :return:
+ """
+ print(caller.GetClassName(), "modified")
+ # Print the interesting stuff.
+ print("\tPosition: ",
+ caller.GetPosition()[0], ", ",
+ caller.GetPosition()[1], ", ",
+ caller.GetPosition()[2])
+ print("\tFocal point: ",
+ caller.GetFocalPoint()[0], ", ",
+ caller.GetFocalPoint()[1], ", ",
+ caller.GetFocalPoint()[2])
+
+
+def Screenshot(fileName, renWin):
+ """
+ Save a screenshot.
+ :param fileName:
+ :param renWin:
+ :return:
+ """
+ windowToImageFilter = vtk.vtkWindowToImageFilter()
+ windowToImageFilter.SetInput(renWin)
+ windowToImageFilter.SetScale(1) # image quality
+ # We are not recording the alpha (transparency) channel.
+ # windowToImageFilter.SetInputBufferTypeToRGBA()
+ windowToImageFilter.SetInputBufferTypeToRGB()
+ # Read from the front buffer.
+ windowToImageFilter.ReadFrontBufferOff()
+ windowToImageFilter.Update()
+
+ writer = vtk.vtkPNGWriter()
+ writer.SetFileName(fileName)
+ writer.SetInputConnection(windowToImageFilter.GetOutputPort())
+ writer.Write()
+
+
+if __name__ == '__main__':
+ main()