ButtonExample

Button.hpp

#pragma once
#ifndef BUTTON_HPP
#define BUTTON_HPP

#include <UtH/Engine/GameObject.hpp>
#include <functional> // Needed for std::function

namespace uth
{
    // RenderTarget forward declaration. If we only use pointers and/or references to a class in a header,
    // we won't need the full definition (No need to include the file). 
    class RenderTarget;
    class Texture;
}

namespace ns
{
    class Button : public uth::GameObject
    {
    public:

        // Button requires knowledge of the render target this button is used with to transform
        // mouse coordinates to world coordinates.
        Button(const uth::RenderTarget& target, uth::Texture* texture);

        void update(float dt) override;

        void setCallback(std::function<void()> callback);

    private:

        const uth::RenderTarget& m_target;
        std::function<void()> m_callback;

    };
}

#endif // BUTTON_HPP

Button.cpp

#include <Button.hpp>
#include <UtH/Platform/Input.hpp>
#include <UtH/Renderer/RenderTarget.hpp>
#include <UtH/Engine/Sprite.hpp>


using namespace ns;

Button::Button(const uth::RenderTarget& target, uth::Texture* texture)
    : GameObject(),
      m_target(target)
{
    // Create a new Sprite component with the loaded texture.
    this->AddComponent(new uth::Sprite(texture));
}

void Button::update(float)
{
    // First check if a click happened.
    if (uthInput.Mouse.IsButtonPressed(uth::Mouse::LEFT))
    {
        // Transform the mouse position into world coordinates.
        auto clickPos = m_target.PixelToCoords(uthInput.Mouse.Position());

        // Check if the mouse position is inside the bounds of this object.
        // Also check callback validity (has it been set?).
        if (transform.GetBounds().contains(clickPos) && m_callback)
            m_callback();
    }
}

void Button::setCallback(std::function<void()> callback)
{
    m_callback = callback;
}