refactor: Factorize computation of the hash for volumes

Author: bruyeret

Sources/Rendering/OpenGL/ImageCPRMapper/index.js

@@ -12,7 +12,10 @@ import vtkReplacementShaderMapper from 'vtk.js/Sources/Rendering/OpenGL/Replacem
 import vtkShaderProgram from 'vtk.js/Sources/Rendering/OpenGL/ShaderProgram';
 import vtkViewNode from 'vtk.js/Sources/Rendering/SceneGraph/ViewNode';
 
-import { getTransferFunctionHash } from 'vtk.js/Sources/Rendering/OpenGL/RenderWindow/resourceSharingHelper';
+import {
+  getTransferFunctionHash,
+  getImageDataHash,
+} from 'vtk.js/Sources/Rendering/OpenGL/RenderWindow/resourceSharingHelper';
 
 import vtkPolyDataVS from 'vtk.js/Sources/Rendering/OpenGL/glsl/vtkPolyDataVS.glsl';
 import vtkPolyDataFS from 'vtk.js/Sources/Rendering/OpenGL/glsl/vtkPolyDataFS.glsl';
@@ -192,7 +195,7 @@ function vtkOpenGLImageCPRMapper(publicAPI, model) {
     }
     const cachedScalarsEntry =
       model._openGLRenderWindow.getGraphicsResourceForObject(scalars);
-    const volumeTextureHash = `${image.getMTime()}A${scalars.getMTime()}`;
+    const volumeTextureHash = getImageDataHash(image, scalars);
     const reBuildTex =
       !cachedScalarsEntry?.oglObject?.getHandle() ||
       cachedScalarsEntry?.hash !== volumeTextureHash;

Sources/Rendering/OpenGL/ImageResliceMapper/index.js

@@ -16,7 +16,10 @@ import vtkShaderProgram from 'vtk.js/Sources/Rendering/OpenGL/ShaderProgram';
 import vtkTransform from 'vtk.js/Sources/Common/Transform/Transform';
 import vtkViewNode from 'vtk.js/Sources/Rendering/SceneGraph/ViewNode';
 
-import { getTransferFunctionHash } from 'vtk.js/Sources/Rendering/OpenGL/RenderWindow/resourceSharingHelper';
+import {
+  getTransferFunctionHash,
+  getImageDataHash,
+} from 'vtk.js/Sources/Rendering/OpenGL/RenderWindow/resourceSharingHelper';
 
 import vtkImageResliceMapperVS from 'vtk.js/Sources/Rendering/OpenGL/glsl/vtkImageResliceMapperVS.glsl';
 import vtkImageResliceMapperFS from 'vtk.js/Sources/Rendering/OpenGL/glsl/vtkImageResliceMapperFS.glsl';
@@ -225,7 +228,7 @@ function vtkOpenGLImageResliceMapper(publicAPI, model) {
     }
 
     const numComp = scalars.getNumberOfComponents();
-    let toString = `${image.getMTime()}A${scalars.getMTime()}`;
+    let toString = getImageDataHash(image, scalars);
 
     const tex = model._openGLRenderWindow.getGraphicsResourceForObject(scalars);
     const reBuildTex = !tex?.oglObject?.getHandle() || tex?.hash !== toString;

Sources/Rendering/OpenGL/RenderWindow/resourceSharingHelper.d.ts

@@ -1,3 +1,5 @@
+import vtkImageData from '../../../Common/DataModel/ImageData';
+import vtkDataArray from '../../../Common/Core/DataArray';
 import { vtkObject } from "../../../interfaces";
 
 /**
@@ -9,6 +11,14 @@ import { vtkObject } from "../../../interfaces";
  */
 export function getTransferFunctionHash(transferFunction: vtkObject | undefined, useIndependentComponents: boolean, numberOfComponents: number): string;
 
+/**
+ * Compute and return a hash than can be used for caching resources
+ *
+ * @param image The image data that contains the scalars
+ * @param scalars The scalars used for rendering
+ */
+export function getImageDataHash(image: vtkImageData, scalars: vtkDataArray): string;
+
 declare const defaultExport: {
   getTransferFunctionHash: typeof getTransferFunctionHash;
 };

Sources/Rendering/OpenGL/RenderWindow/resourceSharingHelper.js

@@ -10,4 +10,8 @@ export function getTransferFunctionHash(
     : '0';
 }
 
-export default { getTransferFunctionHash };
+export function getImageDataHash(image, scalars) {
+  return `${image.getMTime()}A${scalars.getMTime()}`;
+}
+
+export default { getTransferFunctionHash, getImageDataHash };

Sources/Rendering/OpenGL/VolumeMapper/index.js

@@ -24,7 +24,10 @@ import {
 } from 'vtk.js/Sources/Rendering/Core/VolumeProperty/Constants';
 import { BlendMode } from 'vtk.js/Sources/Rendering/Core/VolumeMapper/Constants';
 
-import { getTransferFunctionHash } from 'vtk.js/Sources/Rendering/OpenGL/RenderWindow/resourceSharingHelper';
+import {
+  getTransferFunctionHash,
+  getImageDataHash,
+} from 'vtk.js/Sources/Rendering/OpenGL/RenderWindow/resourceSharingHelper';
 
 import vtkVolumeVS from 'vtk.js/Sources/Rendering/OpenGL/glsl/vtkVolumeVS.glsl';
 import vtkVolumeFS from 'vtk.js/Sources/Rendering/OpenGL/glsl/vtkVolumeFS.glsl';
@@ -1704,7 +1707,7 @@ function vtkOpenGLVolumeMapper(publicAPI, model) {
 
     const tex = model._openGLRenderWindow.getGraphicsResourceForObject(scalars);
     // rebuild the scalarTexture if the data has changed
-    toString = `${image.getMTime()}A${scalars.getMTime()}`;
+    toString = getImageDataHash(image, scalars);
     const reBuildTex = !tex?.oglObject?.getHandle() || tex?.hash !== toString;
     if (reBuildTex) {
       model.scalarTexture = vtkOpenGLTexture.newInstance();