Add a force nearest option for each component of a volume

Sources/Rendering/Core/VolumeMapper/example/controller.html

@@ -10,4 +10,5 @@
   </fieldset>
   <select id='volume' style="margin: 5px;"></select>
   <select id='preset' style="margin: 5px; display: none;"></select>
+  <div id="forceNearest"></div>
 </form>

Sources/Rendering/Core/VolumeMapper/example/index.js

@@ -49,6 +49,7 @@ const reader = vtkHttpDataSetReader.newInstance({ fetchGzip: true });
 const volumeOptions = {};
 const volumeSelectElem = document.getElementById('volume');
 const presetSelectElem = document.getElementById('preset');
+const forceNearestElem = document.getElementById('forceNearest');
 
 const actor = vtkVolume.newInstance();
 const mapper = vtkVolumeMapper.newInstance();
@@ -144,6 +145,14 @@ if (light.getPositional()) {
   renderer.addActor(lca);
 }
 
+{
+  const optionElem = document.createElement('option');
+  optionElem.label = 'Default';
+  optionElem.value = '';
+  presetSelectElem.appendChild(optionElem);
+  presetSelectElem.value = optionElem.value;
+}
+
 Object.keys(ColorMixPreset).forEach((key) => {
   if (key === 'CUSTOM') {
     // Don't enable custom mode
@@ -157,27 +166,41 @@ Object.keys(ColorMixPreset).forEach((key) => {
   presetSelectElem.appendChild(optionElem);
 });
 
-{
-  const optionElem = document.createElement('option');
-  optionElem.label = 'Default';
-  optionElem.value = '';
-  presetSelectElem.appendChild(optionElem);
-}
-
 const setColorMixPreset = (presetKey) => {
   const preset = presetKey ? ColorMixPreset[presetKey] : null;
   actor.getProperty().setColorMixPreset(preset);
   presetSelectElem.value = presetKey;
 };
 
+function updateForceNearestElem(comp) {
+  forceNearestElem.replaceChildren();
+  for (let c = 0; c < comp; ++c) {
+    const checkboxElem = document.createElement('input');
+    checkboxElem.type = 'checkbox';
+    checkboxElem.checked = actor.getProperty().getForceNearestInterpolation(c);
+    checkboxElem.addEventListener('change', () => {
+      actor.getProperty().setForceNearestInterpolation(c, checkboxElem.checked);
+      renderWindow.render();
+    });
+    forceNearestElem.appendChild(checkboxElem);
+    const labelElem = document.createElement('label');
+    labelElem.innerText = `Force linear interpolation for component ${c}`;
+    forceNearestElem.appendChild(labelElem);
+    forceNearestElem.appendChild(document.createElement('br'));
+  }
+}
+
+updateForceNearestElem(1);
+
 volumeSelectElem.addEventListener('change', () => {
   const { comp, data } = volumeOptions[volumeSelectElem.value];
-  setColorMixPreset('');
   if (comp === 1) {
+    setColorMixPreset('');
     presetSelectElem.style.display = 'none';
   } else {
     presetSelectElem.style.display = 'block';
   }
+  updateForceNearestElem(comp);
   const array = mapper.getInputData().getPointData().getArray(0);
   array.setData(data);
   array.setNumberOfComponents(comp);
@@ -200,21 +223,29 @@ reader.setUrl(`${__BASE_PATH__}/data/volume/LIDC2.vti`).then(() => {
     const baseComp = 1;
     const baseData = array.getData();
     const newComp = 2;
-    const newData = new Float32Array(newComp * baseData.length);
+    const cubeData = new Float32Array(newComp * baseData.length);
+    const sphereData = new Float32Array(newComp * baseData.length);
     const dims = imageData.getDimensions();
     for (let z = 0; z < dims[2]; ++z) {
       for (let y = 0; y < dims[1]; ++y) {
         for (let x = 0; x < dims[0]; ++x) {
           const iTuple = x + dims[0] * (y + dims[1] * z);
-          newData[iTuple * newComp + 0] = baseData[iTuple];
-          const isInMask =
+          const isInCube =
             x >= 0.3 * dims[0] &&
             x <= 0.7 * dims[0] &&
             y >= 0.3 * dims[1] &&
             y <= 0.7 * dims[1] &&
             z >= 0.3 * dims[2] &&
             z <= 0.7 * dims[2];
-          newData[iTuple * newComp + 1] = isInMask ? 1 : 0;
+          cubeData[iTuple * newComp + 0] = baseData[iTuple];
+          cubeData[iTuple * newComp + 1] = isInCube ? 1 : 0;
+          const isInSphere =
+            (x / dims[0] - 0.5) ** 2 +
+              (y / dims[1] - 0.5) ** 2 +
+              (z / dims[2] - 0.5) ** 2 <
+            0.2 ** 2;
+          sphereData[iTuple * newComp + 0] = baseData[iTuple];
+          sphereData[iTuple * newComp + 1] = isInSphere ? 1 : 0;
         }
       }
     }
@@ -223,9 +254,13 @@ reader.setUrl(`${__BASE_PATH__}/data/volume/LIDC2.vti`).then(() => {
       comp: baseComp,
       data: baseData,
     };
-    volumeOptions['Labelmap volume'] = {
+    volumeOptions['Sphere labelmap volume'] = {
+      comp: newComp,
+      data: sphereData,
+    };
+    volumeOptions['Cube labelmap volume'] = {
       comp: newComp,
-      data: newData,
+      data: cubeData,
     };
 
     Object.keys(volumeOptions).forEach((key) => {

Sources/Rendering/Core/VolumeProperty/index.d.ts

@@ -135,6 +135,12 @@ export interface vtkVolumeProperty extends vtkObject {
 	 */
 	getUseGradientOpacity(index: number): boolean;
 
+	/**
+	 * @see setForceNearestInterpolation
+	 * @param {Number} index
+	 */
+	getForceNearestInterpolation(index: number): boolean;
+
 	/**
 	 *
 	 */
@@ -315,6 +321,15 @@ export interface vtkVolumeProperty extends vtkObject {
 	 */
 	setComponentWeight(index: number, value: number): boolean;
 
+	/**
+	 * Force the nearest neighbor interpolation of one or more of the components
+	 * The interpolation for the rest of the volume is set using `setInterpolationType`
+	 * @see setInterpolationType
+	 * @param {Number} index
+	 * @param {Boolean} value
+	 */
+	setForceNearestInterpolation(index: number, value: boolean): boolean;
+
 	/**
 	 * Get the scalar component weights.
 	 * @param {Number} index 

Sources/Rendering/Core/VolumeProperty/index.js

@@ -211,6 +211,7 @@ function vtkVolumeProperty(publicAPI, model) {
     'gradientOpacityMaximumValue',
     'gradientOpacityMaximumOpacity',
     'opacityMode',
+    'forceNearestInterpolation',
   ];
   sets.forEach((val) => {
     const cap = macro.capitalize(val);
@@ -232,6 +233,7 @@ function vtkVolumeProperty(publicAPI, model) {
     'gradientOpacityMaximumValue',
     'gradientOpacityMaximumOpacity',
     'opacityMode',
+    'forceNearestInterpolation',
   ];
   gets.forEach((val) => {
     const cap = macro.capitalize(val);
@@ -283,6 +285,7 @@ export function extend(publicAPI, model, initialValues = {}) {
         useGradientOpacity: false,
 
         componentWeight: 1.0,
+        forceNearestInterpolation: false,
       });
     }
   }