fix(webgpu): Fix support of WebGPU render backend

[finetjul]

Context

Running the LineWidget example with WebGPU backend generated an error because WidgetManager requires onWindowResizeEvent public function.
Moreover in many places getOpenGLRenderWindow() was still called (even in a WebGPU context)

Results

Expose onWindowResizeEvent and trigger it when the size of the window is modified.
Rename getOpenGLRenderWindow() into getApiSpecificRenderWindow()

Changes

• Documentation and TypeScript definitions were updated to match those changes

PR and Code Checklist

• semantic-release commit messages
• Run npm run reformat to have correctly formatted code

Testing

• This change adds or fixes unit tests
• Tested environment:
  • vtk.js: master
  • OS: Windows 11
  • Browser: Chrome Canary

[finetjul]

@floryst there is still an error when mousing over the render window. There are many calls to getSelectedDataForXY, eventually model._capturedBuffers is null and model._capturedBuffers.generateSelection() fails.

You must have had that error that would explain why you added the check callID !== model._currentUpdateSelectionCallID.
Any chance you know what is missing here ?

[floryst]

captureBuffers is the issue here. The first call to captureBuffers sets _captureInProgress to true. Subsequent calls (e.g. mouse movement) will see that _captureInProgress == true, so they return early. Importantly, they return when there are no captured buffers.

A quick fix would be the following implementation. I don't know if there are any unintended effects, however. For instance, I don't know if we would need to worry if x1, y1, x2, y2 don't correspond to the current captureInProgress.

@@ -202,22 +202,23 @@ function vtkWidgetManager(publicAPI, model) {
 
   async function captureBuffers(x1, y1, x2, y2) {
     if (model._captureInProgress) {
+      await model._captureInProgress;
       return;
     }
-    model._captureInProgress = true;
     renderPickingBuffer();
 
     model._capturedBuffers = null;
-    model._capturedBuffers = await model._selector.getSourceDataAsync(
+    model._captureInProgress = model._selector.getSourceDataAsync(
       model._renderer,
       x1,
       y1,
       x2,
       y2
     );
+    model._capturedBuffers = await model._captureInProgress;
     model.previousSelectedData = null;
+    model._captureInProgress = null;
     renderFrontBuffer();
-    model._captureInProgress = false;
   }

I did try it out with WebGPU + Chrome Canary, and I don't see anymore getSelection errors. However, the LineWidget cannot be interacted with once placed, and the spheres are not correctly colored. I haven't investigated that bit yet.

[finetjul]

Thanks for your tweak, I added it to the PR.

In WebGPU, there are many rendering warnings which might be related:

In WebGL, it is working the same way as the existing example.

[floryst]

LGTM after the RenderWindow conflict is resolved. Seems like there's more work to do with the WebGPU implementation.

[floryst]

@finetjul I was going to fix the conflicts and realized that model._onSizeChanged is not wired up anywhere. Is there a pathway for invoking the window resize event now that publicAPI.setSize() no longer directly invokes the event?

[floryst]

I'm partially reverting this such that setSize directly invokes the window resize event in both the OpenGL and WebGPU RenderWindows. The changes are all internal, so if you want to continue with the idea you had for _onSizeChanged, you can do that without a breaking change.

[finetjul]

_onSizeChanged was being called since this following commit
63787d5

TBH, I do not remember anything from this current PR though...

[floryst]

Ah, that's good to know. I forgot about that change. We should document it somewhere.