Camera2D.h

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// SPDX-FileCopyrightText: 2026 Valentin Eloy
// SPDX-License-Identifier: GPL-3.0-or-later
 
#pragma once
 
#include <DirectXMath.h>
 
#include "Core/Math/Rect.h"
#include "Core/Math/Vector2.h"

 
namespace hmi {

inline constexpr float LANDING_SHAKE_AMPLITUDE_PIXELS = 2.0f;
inline constexpr float DEATH_SHAKE_AMPLITUDE_PIXELS = 3.0f;
inline constexpr float SCREEN_SHAKE_DURATION = 0.2f;

struct ScreenShakeState {
    float amplitudePixels = 0.0f;
    float elapsed = 0.0f;
    float duration = 0.0f;
};

void triggerScreenShake(ScreenShakeState& state, float amplitudePixels, float duration) noexcept;

void advanceScreenShake(ScreenShakeState& state, float fixedDelta) noexcept;

[[nodiscard]] core::Vector2 screenShakeOffset(const ScreenShakeState& state) noexcept;

class Camera2D {
public:
    static constexpr float PIXELS_PER_UNIT = 16.0f;

    Camera2D(int viewportWidth, int viewportHeight);

    void setViewportSize(int viewportWidth, int viewportHeight);

    void setCenter(const core::Vector2& worldCenter);

    void setZoom(float zoom);

    void setShakeOffsetPixels(const core::Vector2& offsetPixels) {
        _shakeOffsetPixels = offsetPixels;
    }

    [[nodiscard]] const core::Vector2& center() const noexcept {
        return _center;
    }

    [[nodiscard]] float zoom() const noexcept {
        return _zoom;
    }

    [[nodiscard]] DirectX::XMFLOAT4X4 projectionMatrix() const;

    [[nodiscard]] core::Vector2 worldToScreen(const core::Vector2& world) const;

    [[nodiscard]] core::Vector2 screenToWorld(const core::Vector2& screen) const;

    [[nodiscard]] core::Rect visibleBounds() const;

    [[nodiscard]] static float fitZoom(float availableWidth, float availableHeight,
                                       float contentWidth, float contentHeight,
                                       float margin = 1.0f);
 
private:
    [[nodiscard]] float scale() const;
 
    int _viewportWidth;
    int _viewportHeight;
    core::Vector2 _center{};
    float _zoom = 1.0f;
    core::Vector2 _shakeOffsetPixels{};
};
 
}  // namespace hmi