Add Mouse Callback to VisualizerWithKeyCallback

[organic-nailer]

Type

• Bug fix (non-breaking change which fixes an issue): Fixes #
• New feature (non-breaking change which adds functionality). Resolves #
• Breaking change (fix or feature that would cause existing functionality to not work as expected) Resolves #

Motivation and Context

Current Open3D Visualizer provides excellent 3D manipulation capabilities, but there are cases where developers may want to override its behavior. By introducing three additional callback functions for mouse events, developers will be able to handle mouse operations on their side only when necessary.
The addition of mouse operations has also been discussed in some issues: #2610 #4286

Checklist:

• I have run python util/check_style.py --apply to apply Open3D code style
  to my code.
• This PR changes Open3D behavior or adds new functionality.
  • Both C++ (Doxygen) and Python (Sphinx / Google style) documentation is
    updated accordingly.
  • I have added or updated C++ and / or Python unit tests OR included test
    results (e.g. screenshots or numbers) here.
• I will follow up and update the code if CI fails.
• For fork PRs, I have selected Allow edits from maintainers.

Description

I added three callbacks related to mouse event to VisualizerWithKeyCallback.

• MouseMoveCallback
• MouseScrollCallback
• MouseButtonCallback

Usage:

import open3d as o3d

bunny = o3d.data.BunnyMesh()
mesh = o3d.io.read_triangle_mesh(bunny.path)
mesh.compute_vertex_normals()

vis = o3d.visualization.VisualizerWithKeyCallback()

def on_key_action(vis, action, mods):
    print("on_key_action", action, mods)

vis.register_key_action_callback(ord("A"), on_key_action)

def on_mouse_move(vis, x, y):
    print("on_mouse_move", x, y)

def on_mouse_scroll(vis, x, y):
    print("on_mouse_scroll", x, y)

def on_mouse_button(vis, button, action, mods):
    print("on_mouse_button", button, action, mods)

vis.register_mouse_move_callback(on_mouse_move)
vis.register_mouse_scroll_callback(on_mouse_scroll)
vis.register_mouse_button_callback(on_mouse_button)

vis.create_window()
vis.add_geometry(mesh)
vis.run()

Result:

L7PsZ0r5Xotk2nt6.mp4

[update-docs]

Thanks for submitting this pull request! The maintainers of this repository would appreciate if you could update the CHANGELOG.md based on your changes.

[ssheorey]

Looks good in general. Needs testing. Thanks @organic-nailer

[organic-nailer]

Thank you for checking. @ssheorey
How do I add tests? Is there something I can refer to?

[ssheorey]

By testing, I just meant someone other than the PR author trying out the example on a different computer. I've tried it out and it works fine.

I've added your excellent python example to the examples/python/visualization/customized_visualization_key_action.py file and also added C++ docs. Please add Python docs if you get a chance.

[evbernardes]

@organic-nailer this PR just saved me a lot of pain, thank you for this!
If you don't mind it, I have a little question: is it possible to somehow add a callback in register_mouse_button_callback that defaults to the original camera control? Or do I have to re-implement the camera control behavior myself?

For more info, the idea is that depending on the state of an option (set with a keyboard callback) I'll either use my custom function or just use the mouse for camera control as usual.