Shift + Left Mouse Button camera panning is laggy, and does not work when F3D is embedded into a custom GUI

[CV-Tan]

Description

I noticed an issue with camera panning behavior in F3D, especially when embedding F3D into a custom GUI application.

• When using Shift + Left Mouse Button to pan the camera, the movement is very laggy / stuttery.
• When using Middle Mouse Button (press and drag) to pan the camera, the movement is smooth and responsive.
• When integrating libf3d into a custom GUI application (e.g. using an external OpenGL context), Shift + Left Mouse Button panning does not work at all, while middle mouse panning still works correctly.

This makes camera interaction inconsistent and difficult to use in embedded scenarios.

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Expected Behavior

• Camera panning using Shift + Left Mouse Button should be smooth and responsive.
• The behavior should be consistent between:
  • standalone F3D usage
  • embedded / integrated usage inside a custom GUI
• Shift + Left Mouse Button panning should work correctly when mouse and modifier events are forwarded from the host application.

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Actual Behavior

• Shift + Left Mouse Button panning is significantly laggier than middle mouse panning.
• When F3D is embedded into a custom GUI, Shift + Left Mouse Button panning does not trigger camera translation at all.
• Middle mouse panning works correctly in all cases.

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Environment

• F3D version: v3.4.0-RC1
• Platform: Windows
• Integration: Embedded into a custom GUI application
• Rendering backend: OpenGL (external context)

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Additional Notes

• Mouse move and button events are forwarded correctly (rotation and middle mouse panning work as expected).
• Modifier keys (Shift) are correctly detected by the host application.
• The issue seems specific to how Shift + Left Mouse Button interactions are handled in embedded/integrated scenarios.

[mwestphal]

Thanks for opening this issue @CV-Tan

Shift + Left Mouse Button panning is significantly laggier than middle mouse panning.

I do not reproduce this behavior, do you have a specific dataset to reproduce are any dataset from our testing data shows it (https://github.com/f3d-app/f3d/tree/master/testing/data) ?

into a custom GUI application

Which framework are you using ?

[CV-Tan]

Thanks for the quick response.

Dataset

Please try reproducing the issue using the dataset I uploaded in this issue.
With this dataset, Shift + Left Mouse Button panning is noticeably laggier than middle mouse panning on my side.

Reproduction with custom GUI integration (Qt example)

In addition, there is a related issue that can be reproduced using a custom GUI integration, without any additional user code:

• Use the Qt example from the F3D repository (examples/qt)
• Shift + Left Mouse Button panning does not work at all
• Middle mouse panning works as expected

This indicates that the issue is related to GUI framework integration / event handling, and can be reproduced directly using the official Qt example from the F3D repository.

Please let me know if you need more details or a more specific reproduction setup.

testCloudData.zip

[mwestphal]

With this dataset, Shift + Left Mouse Button panning is noticeably laggier than middle mouse panning on my side.

Not laggy at all here, and no difference.

Ill test on Windows when I can, do you have a GPU on your machine ?

Use the Qt example from the F3D repository (examples/qt)
Shift + Left Mouse Button panning does not work at all

I confirm that behavior, but I think maybe its just modifiers missing from the examples, wdyt @Meakk @noclone ?

[noclone]

I can't reproduce the lag, but some modifiers were indeed missing from the integration examples. Fix incoming #2781

[CV-Tan]

https://github.com/user-attachments/assets/d9520883-a2c8-4059-b8ee-d60e42634d21
I have uploaded a short video demonstrating the issue.

The video shows Shift + Left Mouse Button camera panning exhibiting noticeable lag during continuous dragging on Windows 10.
This was recorded using the same dataset and application setup described above.

If needed, I can also provide a comparison video with middle mouse panning.

[mwestphal]

Windows 10.

Windows 10 is not supported anymore (by F3D and Microsoft).
If we can't reproduce on Windows 11, there is nothing we can do.

In any case, I clearly see the lag in the video, Ill try to repro.

[mwestphal]

@CV-Tan the examples in master now support the modifiers as expected.

[mwestphal]

I confirm the lag with the Shift + Left mouse button on Windows.