Add direct cutting-plane control to GLVis scripts

[arotem3]

Motivation

Today, the only way to position the 3D cutting plane from a GLVis script is to replay raw keystrokes via keys. Even a modest plane orientation requires several keystrokes:

keys xxxxxyyyyyyyyi

(5 x presses to rotate phi by 25°, 8 y presses to rotate theta by 40°, then i to enable the plane). Each individual keystroke triggers a full cutting-plane geometry recomputation, not just the final one. On a large mesh that's a lot of wasted computation just to reach a state that could be stated directly in one line.

What this adds

A single script command:

cutting_plane <phi> <theta> <translation> <kind:optional> <alg:optional>

which sets the plane's orientation (degrees), translation, kind (cut-through-elements / solid-cut-behind / off), and algorithm (accurate / fast) directly, in one shot reproducing exactly what the equivalent keystroke sequence would have produced, without the redundant intermediate recomputations. kind defaults to 1 (cut through elements) so the plane is visible immediately; alg is optional and leaves the current value unchanged when omitted.

Implementation

• Plane::SetPlane : new direct setter on the existing Plane class (previously only relative Increase/Decrease mutators existed).
• VisualizationSceneScalarData::SetCuttingPlane : empty-default virtual hook (2D scenes no-op safely).
  VisualizationSceneSolution3d::SetCuttingPlane — override combining plane move + kind + algorithm changes, mirroring the existing key-handler logic.
• cutting_plane registered in the script command table.

[Copilot]

Pull request overview

This PR adds a new cutting_plane GLVis script command to set cutting-plane orientation, translation, kind, and algorithm directly in one call, avoiding the expensive step-by-step recomputation caused by replaying multiple keystrokes.

Changes:

• Introduces Plane::SetPlane() to set cutting-plane orientation/position directly.
• Adds a virtual VisualizationSceneScalarData::SetCuttingPlane() hook and implements it for VisualizationSceneSolution3d.
• Registers and parses a new cutting_plane command in the script controller (degrees in scripts, converted to radians internally).

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
lib/vssolution3d.hpp	Declares VisualizationSceneSolution3d::SetCuttingPlane(...) override.
lib/vssolution3d.cpp	Implements SetCuttingPlane(...) to update plane, kind, algorithm, and trigger recomputation.
lib/vsdata.hpp	Adds Plane::SetPlane(...) and a default no-op SetCuttingPlane(...) hook in the base scene class.
lib/vsdata.cpp	Implements Plane::SetPlane(...) using stored bounding-box center + translation along the plane normal.
lib/script_controller.cpp	Adds the cutting_plane script command, parses optional args, and calls vs->SetCuttingPlane(...).

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[najlkin]

Btw, do not mind the failing CI on mac, it is happening on master as well (https://github.com/GLVis/glvis/actions/runs/29534330078/job/87741910839) 🫣 .

[arotem3]

@najlkin or @camierjs , I am not familiar enough with the GLVis flow control to resolve this copilot comment. Could you please help with this?

[najlkin]

Please use doxygen style. We do not publish it anymore on the webpage, but you can still build it locally.

[najlkin]

Suggested change

	virtual void SetCuttingPlane(double phi, double theta, double translation,
	int kind, int algo) { }
	virtual void SetCuttingPlane(double phi, double theta, double translation,
	int kind = -1, int algo = -1) { }

[najlkin]

Suggested change

	void SetCuttingPlane(double phi, double theta, double translation,
	int kind, int algo) override;
	void SetCuttingPlane(double phi, double theta, double translation,
	int kind = -1, int algo = -1) override;

[najlkin]

Suggested change

	if (algo != -1 && (algo < 0 || algo > 1))
	if (algo < -1 || algo > 1)

[najlkin]

Fix this message please to include -1.

[najlkin]

Suggested change

	(*this)[Command::CuttingPlane] = {"cutting_plane", "<phi> <theta> <translation> <kind:optional, default 1> <alg:optional>", "Set the cutting plane orientation (degrees), translation, kind, and algorithm."};
	(*this)[Command::CuttingPlane] = {"cutting_plane", "<phi> <theta> <translation> [<kind> [<alg>]]", "Set the cutting plane orientation (degrees), translation, kind (default: 1), and algorithm."};