refactor(viewOrientation): use a matrix

Replace getLPSDirections with getSparseOrthogonalMatrix
Replace the array of vectors with a matrix

Author: bruyeret

src/components/core/VtkView/constants.js

@@ -35,8 +35,4 @@ export const DEFAULT_LPS_VIEW_TYPES = {
   [VIEW_TYPE_VALUES.z]: 'Axial',
 };
 
-export const DEFAULT_VIEW_ORIENTATION = [
-  [1, 0, 0],
-  [0, 1, 0],
-  [0, 0, 1],
-];
+export const DEFAULT_VIEW_ORIENTATION = [1, 0, 0, 0, 1, 0, 0, 0, 1];

src/store/views.js

@@ -1,6 +1,9 @@
 import Vue from 'vue';
 import vtkWidgetManager from '@kitware/vtk.js/Widgets/Core/WidgetManager';
 import WidgetManagerConstants from '@kitware/vtk.js/Widgets/Core/WidgetManager/Constants';
+import { getSparseOrthogonalMatrix } from '@kitware/vtk.js/Common/Core/Math';
+
+import { mat3 } from 'gl-matrix';
 
 import {
   DEFAULT_VIEW_TYPE,
@@ -15,7 +18,6 @@ import { DEFAULT_BACKGROUND } from 'paraview-glance/src/components/core/VtkView/
 import {
   remapIdValues,
   wrapMutationAsAction,
-  getLPSDirections,
   updateViewOrientationFromBasisAndAxis,
 } from 'paraview-glance/src/utils';
 
@@ -40,7 +42,7 @@ export default ({ proxyManager }) => ({
     maxTextureLODSize: 50000, // Units are in KiB
     viewOrder: Object.values(VIEW_TYPE_VALUES),
     visibleCount: 1,
-    // a basis in column-major order (list of 3 vectors): number[3][3]
+    // a column-major matrix
     viewOrientation: DEFAULT_VIEW_ORIENTATION,
     // for each view type, the corresponding text to display { viewType: text }
     viewTypes: DEFAULT_VIEW_TYPES,
@@ -225,20 +227,32 @@ export default ({ proxyManager }) => ({
         const masterSource = proxyManager.getProxyById(state.masterSourceId);
         if (masterSource?.getDataset().isA('vtkImageData')) {
           // lps mode with a master volume
+          // directionMatrix is a column major index to world matrix
           const directionMatrix = masterSource.getDataset().getDirection();
-          const lpsDirections = getLPSDirections(directionMatrix);
-          const axisToXYZ = ['x', 'y', 'z'];
+          const sparseDirectionMatrix =
+            getSparseOrthogonalMatrix(directionMatrix);
+
+          const lpsToXyz = {};
+          for (let row = 0; row < 3; ++row) {
+            for (let col = 0; col < 3; ++col) {
+              const index = row + 3 * col;
+              if (sparseDirectionMatrix[index] !== 0) {
+                lpsToXyz['lps'[row]] = 'xyz'[col];
+              }
+            }
+          }
           const viewTypes = {
             [VIEW_TYPE_VALUES.default]: '3D',
-            [VIEW_TYPE_VALUES[axisToXYZ[lpsDirections.l.axis]]]: 'Sagittal',
-            [VIEW_TYPE_VALUES[axisToXYZ[lpsDirections.p.axis]]]: 'Coronal',
-            [VIEW_TYPE_VALUES[axisToXYZ[lpsDirections.s.axis]]]: 'Axial',
+            [VIEW_TYPE_VALUES[lpsToXyz.l]]: 'Sagittal',
+            [VIEW_TYPE_VALUES[lpsToXyz.p]]: 'Coronal',
+            [VIEW_TYPE_VALUES[lpsToXyz.s]]: 'Axial',
           };
-          const viewOrientation = [
-            lpsDirections.l.vector,
-            lpsDirections.p.vector,
-            lpsDirections.s.vector,
-          ];
+
+          // viewOrientation = directionMatrix * transpose(sparseDirectionMatrix)
+          const viewOrientation = Array(3);
+          mat3.transpose(viewOrientation, sparseDirectionMatrix);
+          mat3.mul(viewOrientation, directionMatrix, viewOrientation);
+
           dispatch('setViewTypes', viewTypes);
           dispatch('setViewOrientation', {
             orientation: viewOrientation,

src/utils.js

@@ -115,58 +115,6 @@ export function getCropFilter(pxm, proxy) {
   return volRep.getCropFilter();
 }
 
-/**
- * Function adapted from getLPSDirections lps.ts from VolView.
- * Associates the column vectors of a 3x3 matrix with the LPS axes.
- *
- * For each of the LPS axes, this function returns the associated column index (0, 1, 2)
- * in the provided 3x3 column-major matrix and the corresponding positive vector.
- *
- * Approach:
- *   - find the max of the direction matrix, ignoring columns and rows marked as done
- *   - assign the column vector of that max value to the row axis
- *   - mark that row and column as done
- *   - continue until all rows and columns are done
- */
-export function getLPSDirections(directionMatrix) {
-  const axisToLPS = ['l', 'p', 's'];
-  const lpsDirs = {};
-  // Track the rows and columns that have yet to be assigned.
-  const availableCols = [0, 1, 2];
-  const availableRows = [0, 1, 2];
-
-  for (let i = 0; i < 3; i++) {
-    let bestValue = 0;
-    let bestValueLoc = [0, 0]; // col, row
-    let removeIndices = [0, 0]; // indices into availableCols/Rows for deletion
-
-    availableCols.forEach((col, colIdx) => {
-      availableRows.forEach((row, rowIdx) => {
-        const value = directionMatrix[col * 3 + row];
-        if (Math.abs(value) > Math.abs(bestValue)) {
-          bestValue = value;
-          bestValueLoc = [col, row];
-          removeIndices = [colIdx, rowIdx];
-        }
-      });
-    });
-
-    // the row index corresponds to the index of the LPS axis
-    const [col, axis] = bestValueLoc;
-    const axisVector = directionMatrix.slice(col * 3, (col + 1) * 3);
-    const vecSign = Math.sign(bestValue);
-    const posVector = vec3.scale(Array(3), axisVector, vecSign);
-    lpsDirs[axisToLPS[axis]] = {
-      axis: col,
-      vector: posVector,
-    };
-    availableCols.splice(removeIndices[0], 1);
-    availableRows.splice(removeIndices[1], 1);
-  }
-
-  return lpsDirs;
-}
-
 /**
  * Associate a key of VIEW_TYPE_VALUES to axis index and orientation
  * for forward and upward vectors.
@@ -201,7 +149,7 @@ const MODE_TO_AXES = {
 /**
  * Update the camera view using the given arguments:
  *  - view which is a vtkViewProxy
- *  - basis, a list of 3 vec3 defining a basis
+ *  - basis, a column major matrix defining a basis
  *  - mode, a key of VIEW_TYPE_VALUES
  *  - an optional number of animateSteps
  *
@@ -221,12 +169,12 @@ export function updateViewOrientationFromBasisAndAxis(
     MODE_TO_AXES[mode];
   const forwardVector = vec3.scale(
     Array(3),
-    basis[forwardAxis],
+    basis.slice(forwardAxis * 3, forwardAxis * 3 + 3),
     forwardOrientation
   );
   const upwardVector = vec3.scale(
     Array(3),
-    basis[upwardAxis],
+    basis.slice(upwardAxis * 3, upwardAxis * 3 + 3),
     upwardOrientation
   );
 
@@ -268,6 +216,5 @@ export default {
   remapIdList,
   createRepresentationInAllViews,
   getCropFilter,
-  getLPSDirections,
   updateViewOrientationFromBasisAndAxis,
 };