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engines/ags/engine/game/viewport.h

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+//=============================================================================
+//
+// Definition for the game viewports and cameras.
+//
+//=============================================================================
+
+#ifndef AGS_ENGINE_GAME_VIEWPORT_H
+#define AGS_ENGINE_GAME_VIEWPORT_H
+
+#include "common/std/memory.h"
+#include "common/std/vector.h"
+#include "ags/shared/util/geometry.h"
+#include "ags/shared/util/scaling.h"
+
+namespace AGS3 {
+
+class Camera;
+class Viewport;
+
+typedef std::shared_ptr<Camera> PCamera;
+typedef std::shared_ptr<Viewport> PViewport;
+typedef std::weak_ptr<Camera> CameraRef;
+typedef std::weak_ptr<Viewport> ViewportRef;
+
+// TODO: move to utility header
+// From https://stackoverflow.com/questions/45507041/how-to-check-if-weak-ptr-is-empty-non-assigned
+// Tests that weak_ptr is empty (was not initialized with valid reference)
+template <typename T>
+bool is_uninitialized(std::weak_ptr<T> const &weak) {
+	using wt = std::weak_ptr<T>;
+	return !weak.owner_before(wt{}) &&!wt{} .owner_before(weak);
+}
+
+
+// Camera defines a "looking eye" inside the room, its position and size.
+// It does not render anywhere on its own, instead it is linked to a viewport
+// and latter draws what that camera sees.
+// One camera may be linked to multiple viewports.
+// Camera does not move on its own, this is performed by separate behavior
+// algorithm. But it provides "lock" property that tells if its position is
+// currently owned by user script.
+class Camera {
+public:
+	// Gets camera ID (serves as an index)
+	inline int GetID() const {
+		return _id;
+	}
+	// Sets new camera ID
+	void SetID(int id);
+	// Returns Room camera position and size inside the room (in room coordinates)
+	const Rect &GetRect() const;
+	// Sets explicit room camera's orthographic size
+	void SetSize(const Size sz);
+	// Puts room camera to the new location in the room
+	void SetAt(int x, int y);
+	// Tells if camera is currently locked at custom position
+	bool IsLocked() const;
+	// Locks room camera at its current position
+	void Lock();
+	// Similar to SetAt, but also locks camera preventing it from following player character
+	void LockAt(int x, int y);
+	// Releases camera lock, letting it follow player character
+	void Release();
+
+	// Link this camera to a new viewport; this does not unlink any linked ones
+	void LinkToViewport(ViewportRef viewport);
+	// Unlinks this camera from a given viewport; does nothing if link did not exist
+	void UnlinkFromViewport(int id);
+	// Get the array of linked viewport references
+	const std::vector<ViewportRef> &GetLinkedViewports() const;
+
+	// Tell if this camera has changed recently
+	inline bool HasChangedPosition() const {
+		return _hasChangedPosition;
+	}
+	inline bool HasChangedSize() const {
+		return _hasChangedSize;
+	}
+	// Clears the changed flags
+	void ClearChangedFlags() {
+		_hasChangedPosition = false;
+		_hasChangedSize = false;
+	}
+
+private:
+	int _id = -1;
+	// Actual position and orthographic size
+	Rect _position;
+	// Locked or following player automatically
+	bool _locked = false;
+	// Linked viewport refs, used to notify viewports of camera changes
+	std::vector<ViewportRef> _viewportRefs;
+	// Flags that tell whether this camera's position on screen has changed recently
+	bool _hasChangedPosition = false;
+	bool _hasChangedSize = false;
+};
+
+
+// A result of coordinate conversion between screen and the room,
+// tells which viewport was used to pass the "touch" through.
+typedef std::pair<Point, int> VpPoint;
+
+
+// Viewport class defines a rectangular area on game screen where the contents
+// of a Camera are rendered.
+// Viewport may have one linked camera at a time.
+class Viewport {
+public:
+	// Gets viewport ID (serves as an index)
+	inline int GetID() const {
+		return _id;
+	}
+	// Sets new viewport ID
+	void SetID(int id);
+	// Returns viewport's position on screen
+	inline const Rect &GetRect() const {
+		return _position;
+	}
+	// Returns viewport's room-to-screen transformation
+	inline const AGS::Shared::PlaneScaling &GetTransform() const {
+		return _transform;
+	}
+	// Set viewport's rectangle on screen
+	void SetRect(const Rect &rc);
+	// Sets viewport size
+	void SetSize(const Size sz);
+	// Sets viewport's position on screen
+	void SetAt(int x, int y);
+
+	// Tells whether viewport content is rendered on screen
+	bool IsVisible() const {
+		return _visible;
+	}
+	// Changes viewport visibility
+	void SetVisible(bool on);
+	// Gets the order viewport is displayed on screen
+	int GetZOrder() const {
+		return _zorder;
+	}
+	// Sets the viewport's z-order on screen
+	void SetZOrder(int zorder);
+
+	// Calculates room-to-viewport coordinate conversion.
+	void AdjustTransformation();
+	// Returns linked camera
+	PCamera GetCamera() const;
+	// Links new camera to this viewport, overriding existing link;
+	// pass nullptr to leave viewport without a camera link
+	void LinkCamera(PCamera cam);
+
+	// TODO: provide a Transform object here that does these conversions instead
+	// Converts room coordinates to the game screen coordinates through this viewport;
+	// if clipping is on, the function will fail for room coordinates outside of camera
+	VpPoint RoomToScreen(int roomx, int roomy, bool clip = false) const;
+	// Converts game screen coordinates to the room coordinates through this viewport;
+	// if clipping is on, the function will fail for screen coordinates outside of viewport;
+	// convert_cam_to_data parameter converts camera "game" coordinates to "data" units (legacy mode)
+	VpPoint ScreenToRoom(int scrx, int scry, bool clip = false, bool convert_cam_to_data = false) const;
+
+	// Following functions tell if this viewport has changed recently
+	inline bool HasChangedPosition() const {
+		return _hasChangedPosition;
+	}
+	inline bool HasChangedSize() const {
+		return _hasChangedSize;
+	}
+	inline bool HasChangedVisible() const {
+		return _hasChangedVisible;
+	}
+	inline void SetChangedVisible() {
+		_hasChangedVisible = true;
+	}
+	// Clears the changed flags
+	inline void ClearChangedFlags() {
+		_hasChangedPosition = false;
+		_hasChangedSize = false;
+		_hasChangedVisible = false;
+	}
+
+private:
+	// Parameterized implementation of screen-to-room coordinate conversion
+	VpPoint ScreenToRoomImpl(int scrx, int scry, bool clip, bool convert_cam_to_data);
+
+	int _id = -1;
+	// Position of the viewport on screen
+	Rect _position;
+	// TODO: Camera reference (when supporting multiple cameras)
+	// Coordinate transform between camera and viewport
+	// TODO: need to add rotate conversion to let script API support that;
+	// (maybe use full 3D matrix for that)
+	AGS::Shared::PlaneScaling _transform;
+	// Linked camera reference
+	CameraRef _camera;
+	bool _visible = true;
+	int _zorder = 0;
+	// Flags that tell whether this viewport's position on screen has changed recently
+	bool _hasChangedPosition = false;
+	bool _hasChangedOffscreen = false;
+	bool _hasChangedSize = false;
+	bool _hasChangedVisible = false;
+};
+
+} // namespace AGS3
+
+#endif // AGS_ENGINE_AC_VIEWPORT_H