Selection Manager

Selection Manager

Centralized editor object selection and picking pipeline with single, multi, marquee, and GPU-based selection modes.

Source: SparkEditor/Source/Panels/SelectionManager.h

Overview

The Selection Manager is the single source of truth for which entities are selected in the editor. All panels -- Hierarchy, Inspector, Scene View, Property Grid -- observe selection changes through registered callbacks rather than polling, ensuring consistent state across the entire editor UI.

The system supports multiple selection paradigms: single-click replaces the selection, Ctrl+click adds or toggles individual entities, and marquee (box) selection captures all entities within a screen-space rectangle. GPU picking integrates with an ID render pass where each entity is drawn with a unique color; the clicked pixel's entity ID is fed back through SetPickResult. All selection operations respect the active filter and entity lock state.

Selection groups allow saving and restoring named sets of entities, useful for repeatedly working with the same objects. Entity locking prevents accidental selection of background geometry or locked layers. The callback system uses incrementing IDs so listeners can unregister cleanly.

Key Classes

Class / Struct	Description
SelectionManager	Singleton managing current selection state, marquee, filtering, groups, and callbacks
SelectionChangedEvent	Event payload listing added, removed, and current entities
SelectionFilter	Enum of preset filters: All, StaticMeshOnly, LightsOnly, CamerasOnly, PhysicsOnly, AIOnly, Custom
MarqueeRect	Screen-space rectangle with normalized bounds and point containment test
SelectionGroup	Named collection of entity IDs for save/restore
ScreenPosition	2D screen coordinate for entity picking

Usage

auto& sel = SparkEditor::SelectionManager::GetInstance();
sel.Initialize();

// Listen for selection changes (e.g., from Inspector panel)
auto cbId = sel.OnSelectionChanged([](const SparkEditor::SelectionChangedEvent& e) {
    for (auto id : e.added)
        RefreshInspector(id);
});

// Single select
sel.Select(entityId);

// Multi-select (Ctrl+Click)
sel.AddToSelection(entity2);
sel.ToggleSelection(entity3);

// Marquee selection (mouse drag in scene view)
sel.BeginMarquee(mouseStartX, mouseStartY);
sel.UpdateMarquee(mouseCurX, mouseCurY);
sel.EndMarquee(visibleEntityScreenPositions, /*additive=*/false);

// GPU picking from ID render pass
sel.SetPickResult(entityAtPixel, /*additive=*/holdingCtrl);

// Filter to lights only
sel.SetFilter(SparkEditor::SelectionFilter::LightsOnly);

// Lock background geometry
sel.LockEntity(groundPlaneId);

// Save/restore selection groups
sel.SaveSelectionGroup("BuildingInterior");
sel.RestoreSelectionGroup("BuildingInterior");

// Cleanup
sel.RemoveCallback(cbId);

API Reference

Selection Operations

Method	Return	Description
Select(entityId)	void	Select a single entity, clearing previous selection
AddToSelection(entityId)	void	Add an entity to the current selection
RemoveFromSelection(entityId)	void	Remove an entity from the selection
ToggleSelection(entityId)	void	Toggle an entity's selected state
ClearSelection()	void	Deselect all entities
SelectMultiple(entities)	void	Replace selection with a list of entities

Query

Method	Return	Description
IsSelected(entityId)	bool	Check if an entity is currently selected
GetSelectionCount()	size_t	Number of selected entities
GetSelection()	const vector<EntityId>&	Ordered list of selected entity IDs
GetPrimarySelection()	EntityId	The most recently clicked entity
HasSelection()	bool	Whether anything is selected

Marquee and Picking

Method	Return	Description
BeginMarquee(x, y)	void	Start a marquee rectangle at screen position
UpdateMarquee(x, y)	void	Update the marquee corner as the mouse moves
EndMarquee(positions, additive)	void	Finalize marquee and select contained entities
SetPickResult(entityId, additive)	void	Feed GPU pick result into the selection system

Filtering and Locking

Method	Return	Description
SetFilter(filter)	void	Set a selection filter preset
SetCustomFilter(callback)	void	Set a custom filter function
ClearFilter()	void	Remove all filters
LockEntity(id)	void	Prevent an entity from being selected
UnlockEntity(id)	void	Allow a locked entity to be selected again

Groups and Callbacks

Method	Return	Description
SaveSelectionGroup(name)	void	Save current selection as a named group
RestoreSelectionGroup(name)	void	Restore a saved selection group
DeleteSelectionGroup(name)	void	Delete a named group
OnSelectionChanged(callback)	uint32_t	Register a change listener, returns callback ID
RemoveCallback(callbackId)	void	Unregister a change listener

Related Systems

• Editor Panels -- all panels observe selection via callbacks
• Scene Hierarchy -- tree view drives and reflects selection
• Inspector Panel -- displays properties of selected entities
• Editor Automation -- automation commands can manipulate selection