added files

include/Camera.hpp

@@ -0,0 +1,62 @@
+#pragma once
+
+#include <glm/glm.hpp>
+
+namespace planetarium {
+
+// -----------------------------------------------------------------------
+// Camera
+//
+// A custom orbital ("arcball") camera. It orbits a focus point at a
+// controllable yaw/pitch/distance, with all parameters critically-damped
+// toward their target values every frame so camera moves - including
+// "focus on selected planet" - feel like smooth, cinematic transitions
+// rather than instant snaps.
+// -----------------------------------------------------------------------
+class Camera {
+public:
+    Camera();
+
+    // Input handlers - called directly from Engine's GLFW callbacks.
+    void onMouseDrag(float deltaX, float deltaY);
+    void onMousePan(float deltaX, float deltaY);
+    void onScroll(float deltaY);
+    void reset();
+
+    // Smoothly re-targets the orbit focus to a world-space point (e.g. a
+    // selected planet's position) and optionally suggests a nice viewing
+    // distance for that object's scale.
+    void focusOn(const glm::vec3& worldPoint, float suggestedDistance);
+
+    // Advances the smoothing/interpolation. Must be called once per frame
+    // with the frame's delta time in seconds.
+    void update(float deltaTime);
+
+    glm::mat4 viewMatrix() const;
+    glm::vec3 position() const { return currentPosition_; }
+    glm::vec3 focusPoint() const { return currentFocus_; }
+
+    float distance() const { return currentDistance_; }
+
+private:
+    // Target (goal) state, set instantly by input; current state chases
+    // it every update() call using exponential smoothing.
+    float targetYaw_ = -0.6f;
+    float targetPitch_ = 0.45f;
+    float targetDistance_ = 18.0f;
+    glm::vec3 targetFocus_{0.0f};
+
+    float currentYaw_ = -0.6f;
+    float currentPitch_ = 0.45f;
+    float currentDistance_ = 18.0f;
+    glm::vec3 currentFocus_{0.0f};
+    glm::vec3 currentPosition_{0.0f};
+
+    static constexpr float kMinPitch = -1.45f;
+    static constexpr float kMaxPitch = 1.45f;
+    static constexpr float kMinDistance = 2.0f;
+    static constexpr float kMaxDistance = 400.0f;
+    static constexpr float kSmoothingSpeed = 6.0f;
+};
+
+}  // namespace planetarium