fix(SphereMapper): clear stale VBO shift scale

When `useShiftAndScale` flips from true to false, the mapper previously left
the VBO holding the previous frame's shift/scale state. The freshly packed
VBO data then used identity coordinates while the inverse shift/scale matrix
still applied -- a coordinate mismatch.

Pass `null, null` to `setCoordShiftAndScale` when shift/scale is no longer
needed so the VBO state is cleared.

Author: PaulHax

Sources/Rendering/Core/SphereMapper/test/testSphereMapperShiftScale.js

@@ -0,0 +1,85 @@
+import test from 'tape';
+import testUtils from 'vtk.js/Sources/Testing/testUtils';
+
+import 'vtk.js/Sources/Rendering/Misc/RenderingAPIs';
+import vtkActor from 'vtk.js/Sources/Rendering/Core/Actor';
+import vtkPolyData from 'vtk.js/Sources/Common/DataModel/PolyData';
+import vtkRenderWindow from 'vtk.js/Sources/Rendering/Core/RenderWindow';
+import vtkRenderer from 'vtk.js/Sources/Rendering/Core/Renderer';
+import vtkSphereMapper from 'vtk.js/Sources/Rendering/Core/SphereMapper';
+
+function makePolyDataFromPoints(coords) {
+  const polyData = vtkPolyData.newInstance();
+  polyData.getPoints().setData(Float32Array.from(coords), 3);
+  return polyData;
+}
+
+function updatePoints(polyData, coords) {
+  polyData.getPoints().setData(Float32Array.from(coords), 3);
+  polyData.getPoints().modified();
+  polyData.modified();
+}
+
+function getActivePrimitiveCABOs(openGLRenderWindow, mapper) {
+  const openGLMapper = openGLRenderWindow.getViewNodeFor(mapper);
+  const primitives = openGLMapper.getReferenceByName('primitives');
+  return primitives
+    .map((primitive) => primitive.getCABO())
+    .filter((cabo) => cabo.getElementCount() > 0);
+}
+
+test.onlyIfWebGL(
+  'Test vtkSphereMapper clears VBO shift/scale after shifted points',
+  (t) => {
+    const gc = testUtils.createGarbageCollector(t);
+
+    const container = document.querySelector('body');
+    const renderWindowContainer = gc.registerDOMElement(
+      document.createElement('div')
+    );
+    container.appendChild(renderWindowContainer);
+
+    const renderWindow = gc.registerResource(vtkRenderWindow.newInstance());
+    const renderer = gc.registerResource(vtkRenderer.newInstance());
+    renderWindow.addRenderer(renderer);
+
+    const polyData = gc.registerResource(
+      makePolyDataFromPoints([10000000, 0, 0, 10000001, 0, 0])
+    );
+    const mapper = gc.registerResource(vtkSphereMapper.newInstance());
+    const actor = gc.registerResource(vtkActor.newInstance());
+
+    mapper.setInputData(polyData);
+    mapper.setScalarVisibility(false);
+
+    actor.setMapper(mapper);
+    renderer.addActor(actor);
+
+    const openGLRenderWindow = gc.registerResource(
+      renderWindow.newAPISpecificView()
+    );
+    openGLRenderWindow.setContainer(renderWindowContainer);
+    renderWindow.addView(openGLRenderWindow);
+    openGLRenderWindow.setSize(1, 1);
+
+    renderWindow.render();
+
+    const shiftedCABOs = getActivePrimitiveCABOs(openGLRenderWindow, mapper);
+    t.ok(shiftedCABOs.length > 0, 'sphere VBOs were built');
+    t.ok(
+      shiftedCABOs.some((cabo) => cabo.getCoordShiftAndScaleEnabled()),
+      'far points enable shift/scale on VBOs'
+    );
+
+    updatePoints(polyData, [-0.5, 0, 0, 0.5, 0, 0]);
+    renderWindow.render();
+
+    const unshiftedCABOs = getActivePrimitiveCABOs(openGLRenderWindow, mapper);
+    t.ok(
+      unshiftedCABOs.every((cabo) => !cabo.getCoordShiftAndScaleEnabled()),
+      'VBO shift/scale is cleared once points no longer use it'
+    );
+
+    gc.releaseResources();
+  }
+);

Sources/Rendering/OpenGL/SphereMapper/index.js

@@ -296,9 +296,10 @@ function vtkOpenGLSphereMapper(publicAPI, model) {
 
     const { useShiftAndScale, coordShift, coordScale } =
       computeCoordShiftAndScale(points);
-    if (useShiftAndScale) {
-      vbo.setCoordShiftAndScale(coordShift, coordScale);
-    }
+    vbo.setCoordShiftAndScale(
+      useShiftAndScale ? coordShift : null,
+      useShiftAndScale ? coordScale : null
+    );
 
     //
     // Generate points and point data for sides