DOCS: Add custom volume rendering example

Author: Thibault-Pelletier

Docs/examples.md

@@ -10,3 +10,17 @@
 :language: python
 :linenos:
 ```
+
+### Volume Rendering Pipeline
+
+![Volume Rendering Example](images/volume_rendering_example.jpg)
+
+```{literalinclude} ../Examples/Python/CustomVR/CustomVR.py
+:language: python
+:linenos:
+```
+
+```{literalinclude} ../Examples/Python/CustomVR/CustomVRLib/CustomVRPipeline.py
+:language: python
+:linenos:
+```

Docs/images/volume_rendering_example.jpg

@@ -1,6 +1,6 @@
 # Welcome to the Slicer Layer Displayable Manager's documentation!
 
-![Welcome to Slicer Layer DM](https://raw.githubusercontent.com/KitwareMedical/SlicerLayerDisplayableManager/main/Doc/LayerDisplayableManager.png)
+![Welcome to Slicer Layer DM](https://raw.githubusercontent.com/KitwareMedical/SlicerLayerDisplayableManager/main/Docs/LayerDisplayableManager.png)
 
 
 Slicer Layer DM is a [3D Slicer](https://github.com/Slicer/Slicer/) extension simplifying the creation of new display

Docs/index.md

@@ -0,0 +1,94 @@
+"""
+This example shows how to create a custom volume rendering for a volume node using the SlicerLayerDisplayableManager
+extension.
+
+It goes over the following concepts:
+    - Creates a VR display pipeline on a selected volume node in the scene
+    - Register the pipeline creation mechanism
+
+Usage:
+    This example is implemented as a scripted module and can be added as such to Slicer.
+    Due to import order considerations, the pipeline code is lazy loaded from the CustomVRLib python package.
+"""
+
+import qt
+import slicer
+from slicer.ScriptedLoadableModule import ScriptedLoadableModule, ScriptedLoadableModuleWidget
+
+
+class CustomVR(ScriptedLoadableModule):
+    def __init__(self, parent):
+        ScriptedLoadableModule.__init__(self, parent)
+        self.parent.title = "Custom VR Pipeline Example"
+        self.parent.categories = ["qSlicerAbstractCoreModule", "Examples"]
+        self.parent.dependencies = []
+        self.parent.contributors = []
+        self.parent.helpText = ""
+        self.parent.acknowledgementText = ""
+
+
+class CustomVRWidget(ScriptedLoadableModuleWidget):
+    """
+    In this example, we will display a custom volume rendering and use VTK compute shader for processing the volume.
+    To avoid initialization problems, the pipeline registration is done lazily during the setup.
+    """
+
+    def setup(self) -> None:
+        from CustomVRLib import registerPipeline
+
+        registerPipeline()
+        ScriptedLoadableModuleWidget.setup(self)
+
+        widget = qt.QWidget()
+        layout = qt.QVBoxLayout(widget)
+
+        # Configure volume selector node
+        self._volumeNodeSelector = slicer.qMRMLNodeComboBox(widget)
+        self._volumeNodeSelector.nodeTypes = ["vtkMRMLVolumeNode"]
+        self._volumeNodeSelector.selectNodeUponCreation = True
+        self._volumeNodeSelector.addEnabled = False
+        self._volumeNodeSelector.removeEnabled = False
+        self._volumeNodeSelector.showHidden = False
+        self._volumeNodeSelector.renameEnabled = True
+        self._volumeNodeSelector.setMRMLScene(slicer.mrmlScene)
+        layout.addWidget(self._volumeNodeSelector)
+
+        # Configure toggle button
+        toggleDisplayButton = qt.QPushButton("Toggle display")
+        toggleDisplayButton.clicked.connect(self._toggleVolumeDisplay)
+        layout.addWidget(toggleDisplayButton)
+        layout.addStretch()
+
+        self.layout.addWidget(widget)
+
+    def _toggleVolumeDisplay(self, *_):
+        from CustomVRLib import CustomVRPipeline
+
+        volumeNode = self._volumeNodeSelector.currentNode()
+        if not volumeNode:
+            return
+
+        wasVisible = CustomVRPipeline.GetVRNodeVisibility(volumeNode, slicer.mrmlScene)
+        vrNode = CustomVRPipeline.CreateVRNode(volumeNode, slicer.mrmlScene)
+        CustomVRPipeline.SetVRNodeVisible(vrNode, not wasVisible)
+
+    def onReload(self):
+        """
+        Customization of reload to allow reloading of the CustomVRLib files.
+        """
+        import importlib
+
+        packageName = "CustomVRLib"
+        submodules = ["CustomVRPipeline"]
+
+        # Reload the package
+        module = importlib.import_module(packageName)
+        importlib.reload(module)
+
+        # Reload submodules
+        for sub in submodules:
+            fullName = f"{packageName}.{sub}"
+            submodule = importlib.import_module(fullName)
+            importlib.reload(submodule)
+
+        ScriptedLoadableModuleWidget.onReload(self)