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 +1,64 @@
+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';
+import vtkSliceHelper from 'vtk.js/Sources/Rendering/Core/SliceHelper';
+
+// ----------------------------------------------------------------------------
+// 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 = vtkSliceHelper.newInstance({ 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/SliceHelper/index.js

@@ -0,0 +1,82 @@
+import macro from 'vtk.js/Sources/macros';
+import vtkPlane from 'vtk.js/Sources/Common/DataModel/Plane';
+
+function vtkSliceHelper(publicAPI, model) {
+  model.classHierarchy.push('vtkSliceHelper');
+
+  const superClass = { ...publicAPI };
+
+  function update() {
+    const [x, y, z] = model.normal;
+    model.clipPlane1.setNormal([x, y, z]);
+    model.clipPlane2.setNormal([-x, -y, -z]);
+
+    const origin1 = [
+      model.origin[0] - (x * model.thickness) / 2,
+      model.origin[1] - (y * model.thickness) / 2,
+      model.origin[2] - (z * model.thickness) / 2,
+    ];
+    model.clipPlane1.setOrigin(origin1);
+
+    const origin2 = [
+      model.origin[0] + (x * model.thickness) / 2,
+      model.origin[1] + (y * model.thickness) / 2,
+      model.origin[2] + (z * model.thickness) / 2,
+    ];
+    model.clipPlane2.setOrigin(origin2);
+  }
+
+  publicAPI.addMapper = (mapper) => {
+    mapper.addClippingPlane(model.clipPlane1);
+    mapper.addClippingPlane(model.clipPlane2);
+  };
+
+  publicAPI.setThickness = (thickness) => {
+    superClass.setThickness(thickness);
+    update();
+  };
+  publicAPI.setOrigin = (origin) => {
+    superClass.setOrigin(origin);
+    update();
+  };
+  publicAPI.setNormal = (normal) => {
+    superClass.setNormal(normal);
+    update();
+  };
+}
+
+// ----------------------------------------------------------------------------
+// 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);
+
+  model.clipPlane1 = vtkPlane.newInstance();
+  model.clipPlane2 = vtkPlane.newInstance();
+
+  // Build VTK API
+  macro.obj(publicAPI, model);
+  macro.setGet(publicAPI, model, ['thickness', 'origin', 'normal']);
+
+  // Object methods
+  vtkSliceHelper(publicAPI, model);
+
+  if (initialValues.mapper) {
+    publicAPI.addMapper(initialValues.mapper);
+  }
+}
+
+// ----------------------------------------------------------------------------
+
+export const newInstance = macro.newInstance(extend, 'vtkSliceHelper');
+
+// ----------------------------------------------------------------------------
+
+export default { newInstance, extend };