COMP: Fix -Wunused-parameter in ctkVTKRenderView::lookFromAxis()

[jcfr]

The fov parameter became obsolete following d620ad9 (BUG: Fix
unexpected camera position change in ctkVTKRenderView::lookFromAxis)

[jcfr]

It looks like we should update the docstring to document the API change introduced in d620ad9 and explain the fov parameter has no effect:

CTK/Libs/Visualization/VTK/Widgets/ctkVTKRenderView.h

Lines 121 to 125 in 08461b3

	/// \brief Change camera to look from a given axis to the focal point
	/// Translate/Rotate the camera to look from a given axis
	/// The Field of View (fov) controls how far from the focal point the
	/// camera must be (final_pos = focal_point + 3*fov).
	void lookFromAxis(const ctkAxesWidget::Axis& axis, double fov = 10.);

@Sunderlandkyl Could you suggest an updated docstring ?

[Sunderlandkyl]

I don't remember making this commit, so I'm not sure what changed.
Maybe @lassoan made the change from the Mac laptop while I was still signed into Git there?

[lassoan]

I've made that change and indeed the FOV parameter is not used anymore. It was not a good idea to force changing the camera distance from the focal point when the user only requested a view direction change.

I think the cleanest solution would be to have two versions of this method:

• void lookFromAxis(const ctkAxesWidget::Axis& axis, double fov); -> deprecated, log a warning message when used, remove it in a few years
• void lookFromAxis(const ctkAxesWidget::Axis& axis);

[jcfr]

Since all comments have been addressed, I plan on merging after the checks are complete and ✔️ .