feat(sliceHelper): add helper for slicing imageMapper with clip planes

To deprecate vtkInteractorStyleMPRSlice I add a helper using two
clip planes instead. The included example is similar to
vtkInteractorStyleMPRSlice example.

re #1872

Author: DrewLazzeriKitware

Examples/Volume/MPRSlice/index.js

@@ -0,0 +1,60 @@
+import 'vtk.js/Sources/favicon';
+/* eslint-disable */
+
+import 'vtk.js/Sources/Rendering/Profiles/Volume';
+
+// Force DataAccessHelper to have access to various data source
+import 'vtk.js/Sources/IO/Core/DataAccessHelper/HtmlDataAccessHelper';
+import 'vtk.js/Sources/IO/Core/DataAccessHelper/HttpDataAccessHelper';
+import 'vtk.js/Sources/IO/Core/DataAccessHelper/JSZipDataAccessHelper';
+
+import vtkHttpDataSetReader from 'vtk.js/Sources/IO/Core/HttpDataSetReader';
+import vtkFullScreenRenderWindow from 'vtk.js/Sources/Rendering/Misc/FullScreenRenderWindow';
+import vtkVolume from 'vtk.js/Sources/Rendering/Core/Volume';
+import vtkVolumeMapper from 'vtk.js/Sources/Rendering/Core/VolumeMapper';
+
+// ----------------------------------------------------------------------------
+// Standard rendering code setup
+// ----------------------------------------------------------------------------
+
+const fullScreenRenderer = vtkFullScreenRenderWindow.newInstance({
+  background: [0, 0, 0],
+});
+const renderer = fullScreenRenderer.getRenderer();
+const renderWindow = fullScreenRenderer.getRenderWindow();
+
+global.fullScreen = fullScreenRenderer;
+global.renderWindow = renderWindow;
+
+// ----------------------------------------------------------------------------
+// Example code
+// ----------------------------------------------------------------------------
+
+const reader = vtkHttpDataSetReader.newInstance({ fetchGzip: true });
+const actor = vtkVolume.newInstance();
+const mapper = vtkVolumeMapper.newInstance();
+mapper.setSampleDistance(1.1);
+actor.setMapper(mapper);
+mapper.setInputConnection(reader.getOutputPort());
+
+const mprSlice = vtkVolumeMapper.vtkSliceHelper.newInstance();
+mprSlice.setMapper(mapper);
+
+reader.setUrl(`${__BASE_PATH__}/data/volume/headsq.vti`).then(() => {
+  reader.loadData().then(() => {
+    const data = reader.getOutputData();
+    renderer.addVolume(actor);
+    const [xMin, xMax, yMin, yMax, zMin, zMax] = data.getBounds();
+    mprSlice.setOrigin((xMin + xMax) / 2, (yMin + yMax) / 2, (zMin + zMax) / 2);
+
+    renderer.resetCamera();
+    renderWindow.render();
+  });
+});
+
+// Set MPR slice to follow camera orientation
+const camera = renderer.getActiveCamera();
+camera.onModified(() => {
+  const direction = camera.getDirectionOfProjection();
+  mprSlice.setNormal(direction);
+});

Sources/Rendering/Core/VolumeMapper/SliceHelper.js

@@ -0,0 +1,82 @@
+import macro from 'vtk.js/Sources/macros';
+import * as vtkMath from 'vtk.js/Sources/Common/Core/Math';
+import vtkPlane from 'vtk.js/Sources/Common/DataModel/Plane';
+
+function vtkSliceHelper(publicAPI, model) {
+  model.classHierarchy.push('vtkSliceHelper');
+
+  model.clipPlane1 = vtkPlane.newInstance();
+  model.clipPlane2 = vtkPlane.newInstance();
+
+  const superClass = { ...publicAPI };
+
+  function update() {
+    const n1 = model.clipPlane1.getNormalByReference();
+    n1[0] = model.normal[0];
+    n1[1] = model.normal[1];
+    n1[2] = model.normal[2];
+
+    const n2 = model.clipPlane2.getNormalByReference();
+    n2[0] = -model.normal[0];
+    n2[1] = -model.normal[1];
+    n2[2] = -model.normal[2];
+
+    vtkMath.multiplyAccumulate(
+      model.origin,
+      model.normal,
+      -model.thickness / 2,
+      model.clipPlane1.getOriginByReference()
+    );
+
+    vtkMath.multiplyAccumulate(
+      model.origin,
+      model.normal,
+      model.thickness / 2,
+      model.clipPlane2.getOriginByReference()
+    );
+
+    model.clipPlane1.modified();
+    model.clipPlane2.modified();
+  }
+
+  const subscription = publicAPI.onModified(update);
+  publicAPI.delete = () => {
+    superClass.delete();
+    subscription.unsubscribe();
+  };
+
+  publicAPI.setMapper = (mapper) => {
+    mapper.addClippingPlane(model.clipPlane1);
+    mapper.addClippingPlane(model.clipPlane2);
+  };
+}
+
+// ----------------------------------------------------------------------------
+// Object factory
+// ----------------------------------------------------------------------------
+
+const DEFAULT_VALUES = {
+  thickness: 3,
+  origin: [0, 0, 0],
+  normal: [1, 0, 0],
+};
+
+export function extend(publicAPI, model, initialValues = {}) {
+  Object.assign(model, DEFAULT_VALUES, initialValues);
+
+  // Build VTK API
+  macro.obj(publicAPI, model);
+  macro.setGet(publicAPI, model, ['thickness']);
+  macro.setGetArray(publicAPI, model, ['origin', 'normal'], 3);
+
+  // Object methods
+  vtkSliceHelper(publicAPI, model);
+}
+
+// ----------------------------------------------------------------------------
+
+export const newInstance = macro.newInstance(extend, 'vtkSliceHelper');
+
+// ----------------------------------------------------------------------------
+
+export default { newInstance, extend };

Sources/Rendering/Core/VolumeMapper/index.js

@@ -2,6 +2,7 @@ import macro from 'vtk.js/Sources/macros';
 import * as vtkMath from 'vtk.js/Sources/Common/Core/Math';
 import Constants from 'vtk.js/Sources/Rendering/Core/VolumeMapper/Constants';
 import vtkAbstractMapper from 'vtk.js/Sources/Rendering/Core/AbstractMapper';
+import vtkSliceHelper from 'vtk.js/Sources/Rendering/Core/VolumeMapper/SliceHelper';
 
 const { BlendMode, FilterMode } = Constants;
 
@@ -126,4 +127,4 @@ export const newInstance = macro.newInstance(extend, 'vtkVolumeMapper');
 
 // ----------------------------------------------------------------------------
 
-export default { newInstance, extend };
+export default { newInstance, extend, vtkSliceHelper };

Sources/Rendering/Core/index.js

@@ -79,6 +79,7 @@ export default {
   vtkRenderWindowInteractor,
   vtkScalarBarActor,
   vtkSkybox,
+  vtkSliceHelper: vtkVolumeMapper.vtkSliceHelper,
   vtkSphereMapper,
   vtkStickMapper,
   vtkTexture,