Added GenerateModelsFromLabels and some minor fixes

src/PythonicAPI.md

@@ -235,6 +235,7 @@ This section includes ?vtkUnstructuredGrid?.
 
 | Example Name | Description | Image |
 | -------------- | ------------- | ------- |
+[GenerateModelsFromLabels](/PythonicAPI/Medical/GenerateModelsFromLabels) | Create models from labeled volume data.
 [MedicalDemo1](/PythonicAPI/Medical/MedicalDemo1) | Create a skin surface from volume data.
 
 ### Surface reconstruction

src/PythonicAPI/Medical/GenerateCubesFromLabels.md

+### Description
+
+Sometimes it is helpful to view the results of a segmentation without any post processing. This example converts the point data from a labeled volume into cell data. The surfaces are displayed as vtkPolydata. If you want to created smoothed polydata models from your segmented volumes, see the example [GenerateModelsFromLabels](../GenerateModelsFromLabels). The input volume must be in [MetaIO format](http://www.vtk.org/Wiki/MetaIO/Documentation).
+
+``` text
+ Usage: GenerateCubesFromLabels InputVolume.mhd StartLabel EndLabel
+      where
+        InputVolume is a meta file containing a 3 volume of discrete labels.
+        StartLabel is the first label to be processed
+        EndLabel is the last label to be processed
+        NOTE: There can be gaps in the labeling. If a label does not exist in the volume, it will be skipped.
+```
+
+!!! note
+    This original source code for this example is [here](https://gitlab.kitware.com/vtk/vtk/blob/395857190c8453508d283958383bc38c9c2999bf/Examples/Medical/Cxx/GenerateCubesFromLabels.cxx).

src/PythonicAPI/Medical/GenerateCubesFromLabels.py

+#!/usr/bin/env python3
+
+from dataclasses import dataclass
+
+# noinspection PyUnresolvedReferences
+import vtkmodules.vtkInteractionStyle
+# noinspection PyUnresolvedReferences
+import vtkmodules.vtkRenderingOpenGL2
+from vtkmodules.vtkCommonColor import vtkNamedColors
+from vtkmodules.vtkCommonDataModel import (
+    vtkDataObject,
+    vtkDataSetAttributes
+)
+from vtkmodules.vtkCommonTransforms import vtkTransform
+from vtkmodules.vtkFiltersCore import vtkThreshold
+from vtkmodules.vtkFiltersGeneral import vtkTransformFilter
+from vtkmodules.vtkFiltersGeometry import vtkGeometryFilter
+from vtkmodules.vtkIOImage import vtkMetaImageReader
+from vtkmodules.vtkImagingCore import vtkImageWrapPad
+from vtkmodules.vtkInteractionWidgets import vtkCameraOrientationWidget
+from vtkmodules.vtkRenderingCore import (
+    vtkActor,
+    vtkPolyDataMapper,
+    vtkRenderWindow,
+    vtkRenderWindowInteractor,
+    vtkRenderer
+)
+
+
+def main():
+    colors = vtkNamedColors()
+
+    file_name, start_label, end_label = get_program_parameters()
+    if start_label > end_label:
+        end_label, start_label = start_label, end_label
+
+    # Generate cubes from labels
+    # 1) Read the meta file
+    # 2) Convert point data to cell data
+    # 3) Convert to geometry and display
+
+    reader = vtkMetaImageReader(file_name=file_name)
+    reader.update()
+
+    # Pad the volume so that we can change the point data into cell
+    # data.
+    extent = reader.output.extent
+    padded_extent = (extent[0], extent[1] + 1, extent[2], extent[3] + 1, extent[4], extent[5] + 1)
+    pad = vtkImageWrapPad(output_whole_extent=padded_extent)
+    (reader >> pad).update()
+
+    # Copy the scalar point data of the volume into the scalar cell data
+    pad.output.cell_data.SetScalars(reader.output.point_data.scalars)
+
+    selector = vtkThreshold(input_array_to_process=(0, 0, 0,
+                                                    vtkDataObject.FIELD_ASSOCIATION_CELLS,
+                                                    vtkDataSetAttributes.SCALARS),
+                            lower_threshold=start_label, upper_threshold=end_label)
+
+    # Shift the geometry by 1/2
+    transform = vtkTransform()
+    transform.Translate(-0.5, -0.5, -0.5)
+
+    transform_model = vtkTransformFilter(transform=transform)
+
+    geometry = vtkGeometryFilter()
+
+    mapper = vtkPolyDataMapper(scalar_range=(start_label, end_label),
+                               scalar_mode=Mapper.ScalarMode.VTK_SCALAR_MODE_USE_CELL_DATA,
+                               color_mode=Mapper.ColorMode.VTK_COLOR_MODE_MAP_SCALARS)
+    pad >> selector >> transform_model >> geometry >> mapper
+
+    actor = vtkActor(mapper=mapper)
+
+    renderer = vtkRenderer(background=colors.GetColor3d('DarkSlateBlue'))
+    render_window = vtkRenderWindow(size=(640, 480), window_name='GenerateCubesFromLabels')
+    render_window.AddRenderer(renderer)
+
+    render_window_interactor = vtkRenderWindowInteractor()
+    render_window_interactor.render_window = render_window
+
+    renderer.AddActor(actor)
+
+    render_window.Render()
+
+    camera = renderer.GetActiveCamera()
+    camera.position = (130.171200, 942.438334, -262.344068)
+    camera.focal_point = (279.491372, 262.325784, 172.209964)
+    camera.view_up = (0.235239, -0.486113, -0.841639)
+    camera.distance = 820.784260
+    camera.clipping_range = (224.710879, 1514.926115)
+
+    omw = vtkCameraOrientationWidget(parent_renderer=renderer)
+    # Enable the widget.
+    omw.On()
+
+    render_window_interactor.Start()
+
+
+def get_program_parameters():
+    import argparse
+    description = 'Convert the point data from a labeled volume into cell data.'
+    epilogue = '''
+ The surfaces are displayed as vtkPolydata.
+     '''
+    parser = argparse.ArgumentParser(description=description, epilog=epilogue,
+                                     formatter_class=argparse.RawDescriptionHelpFormatter)
+    parser.add_argument('filename', help='Input volume e.g. Frog/frogtissue.mhd.')
+    parser.add_argument('startlabel', type=int, help='The starting label in the input volume, e,g, 1.')
+    parser.add_argument('endlabel', type=int, help='The ending label in the input volume e.g. 29')
+    args = parser.parse_args()
+    return args.filename, args.startlabel, args.endlabel
+
+
+@dataclass(frozen=True)
+class Mapper:
+    @dataclass(frozen=True)
+    class ColorMode:
+        VTK_COLOR_MODE_DEFAULT: int = 0
+        VTK_COLOR_MODE_MAP_SCALARS: int = 1
+        VTK_COLOR_MODE_DIRECT_SCALARS: int = 2
+
+    @dataclass(frozen=True)
+    class ResolveCoincidentTopology:
+        VTK_RESOLVE_OFF: int = 0
+        VTK_RESOLVE_POLYGON_OFFSET: int = 1
+        VTK_RESOLVE_SHIFT_ZBUFFER: int = 2
+
+    @dataclass(frozen=True)
+    class ScalarMode:
+        VTK_SCALAR_MODE_DEFAULT: int = 0
+        VTK_SCALAR_MODE_USE_POINT_DATA: int = 1
+        VTK_SCALAR_MODE_USE_CELL_DATA: int = 2
+        VTK_SCALAR_MODE_USE_POINT_FIELD_DATA: int = 3
+        VTK_SCALAR_MODE_USE_CELL_FIELD_DATA: int = 4
+        VTK_SCALAR_MODE_USE_FIELD_DATA: int = 5
+
+
+if __name__ == '__main__':
+    main()

src/PythonicAPI/Snippets.md

@@ -7,7 +7,7 @@ Snippets are chunks of code that can be cut (*snipped*) and pasted into examples
 
 | Snippet | Description | |
 | -------------- | ------------- | ------- |
-[CameraPosition](/PythonicAPI/Snippets/CameraPosition.md) | Read all VTK polydata file types.
+[CameraPosition](/PythonicAPI/Snippets/CameraPosition.md) | Get the camera position and focal point.
 [CheckVTKVersion](/PythonicAPI/Snippets/CheckVTKVersion.md) | Check the VTK version returning `True` if the requested VTK version is >= the current version.
 [DrawViewportBorder](/PythonicAPI/Snippets/DrawViewportBorder.md) | Draw a border around a renderer's viewport.
 [GetProgramParameters](/PythonicAPI/Snippets/GetProgramParameters.md) | Get the program parameters.

src/PythonicAPI/Snippets/CameraPosition.md

@@ -21,7 +21,7 @@ def camera_modified_callback(caller, event):
     res += f'\tcamera.position = ({", ".join(map("{0:0.6f}".format, caller.position))})\n'
     res += f'\tcamera.focal_point = ({", ".join(map("{0:0.6f}".format, caller.focal_point))})\n'
     res += f'\tcamera.view_up = ({", ".join(map("{0:0.6f}".format, caller.view_up))})\n'
-    res += f'\tcamera.distance = ({"{0:0.6f}".format(caller.GetDistance())})\n'
+    res += f'\tcamera.distance = {"{0:0.6f}".format(caller.GetDistance())}\n'
     res += f'\tcamera.clipping_range = ({", ".join(map("{0:0.6f}".format, caller.clipping_range))})\n'
     print(res)