Button Click System

Source: client/engine/systems/systems_functions/ButtonClickSystem.cpp

Purpose: Detect mouse hover and click on clickable entities, fire their callbacks, and update their visual color state.

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Components Used

Component	Access	Description
HitBox	Read	Size and scaling behavior
Clickable	Read/Write	Hover/click state, colors, callback
Drawable	Write	Sprite color updated
Transform	Read	Position, scale, origin

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Dependencies

Dependency	Type	Description
GameWorld	Reference	Access to InputManager and window
InputManager	Via GameWorld	Mouse button state queries

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Behavior

1. Focus Check: Returns immediately if the window doesn't have focus
2. Mouse Button Query: Uses InputManager::IsMouseButtonPressed() for backend-agnostic mouse state
3. Hit Detection: For each clickable entity:
   • Converts mouse position to world coords via window_.mapPixelToCoords
   • Builds the clickable rectangle considering transform scale and origin
   • Sets isHovered when pointer is inside the rectangle
4. Click Detection: Fires on button release after being pressed on the same entity
5. Visual Feedback: Updates drawable.color based on state priority: clickColor > hoverColor > idleColor

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Function Signature

void ButtonClickSystem(Engine::registry &reg, GameWorld &game_world,
    Engine::sparse_array<Component::HitBox> &hit_boxes,
    Engine::sparse_array<Component::Clickable> &clickables,
    Engine::sparse_array<Component::Drawable> &drawables,
    Engine::sparse_array<Component::Transform> &transforms);

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Implementation Notes

The system uses the InputManager abstraction for mouse queries:

// Query mouse button through InputManager (backend-agnostic)
const bool is_left_pressed =
    game_world.input_manager_->IsMouseButtonPressed(
        Engine::Input::MouseButton::Left);

This ensures the button click system works regardless of the underlying input backend (SFML, SDL, etc.).

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Notes

• Backend Agnostic: Uses InputManager for mouse state, not sf::Mouse directly
• Click fires on release: Not on press, for better UX
• Colors applied directly: No shader required for visual feedback

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Related Documentation

• Input Abstraction Layer - Mouse button abstraction
• Input System - Keyboard input handling