/****************************************************************************

 Copyright (c) 2018  GeometryFactory Sarl (France).
 Copyright (C) 2002-2014 Gilles Debunne. All rights reserved.

 This file is part of a fork of the QGLViewer library version 2.7.0.

*****************************************************************************/
// $URL: https://github.com/CGAL/cgal/blob/v6.1/GraphicsView/include/CGAL/Qt/camera.h $
// $Id: include/CGAL/Qt/camera.h b26b07a1242 $
// SPDX-License-Identifier: GPL-3.0-only


#ifndef QGLVIEWER_CAMERA_H
#define QGLVIEWER_CAMERA_H
#include <array>
#include <QMap>
#include <CGAL/Qt/vec.h>
#include <CGAL/Qt/quaternion.h>
#include <CGAL/export/Qt.h>
#include <QOpenGLFunctions_2_1>
#include <QOpenGLFunctions>

namespace CGAL{
class QGLViewer;
namespace qglviewer {

class KeyFrameInterpolator;
class Frame;
class ManipulatedCameraFrame;


/*! \brief A perspective or orthographic camera.
  \class Camera camera.h CGAL::QGLViewer/camera.h

  A Camera defines some intrinsic parameters (fieldOfView(), position(),
  viewDirection(), upVector()...) and useful positioning tools that ease its
  placement (showEntireScene(), fitSphere(), lookAt()...). It exports its
  associated OpenGL projection and modelview matrices and can interactively be
  modified using the mouse.

  <h3>Mouse manipulation</h3>

  The position() and orientation() of the Camera are defined by a
  ManipulatedCameraFrame (retrieved using frame()). These methods are just
  convenient wrappers to the equivalent Frame methods. This also means that the
  Camera frame() can be attached to a Frame::referenceFrame() which enables
  complex Camera setups.

  Different displacements can be performed using the mouse. The list of possible
  actions is defined by the CGAL::QGLViewer::MouseAction enum. Use
  CGAL::QGLViewer::setMouseBinding() to attach a specific action to an arbitrary mouse
  button-state key binding. These actions are detailed in the <a
  href="../mouse.html">mouse page</a>.

  The default button binding are: CGAL::QGLViewer::ROTATE (left), CGAL::QGLViewer::ZOOM
  (middle) and CGAL::QGLViewer::TRANSLATE (right). With this configuration, the Camera
  \e observes a scene and rotates around its pivotPoint(). You can switch
  between this mode and a fly mode using the CGAL::QGLViewer::CAMERA_MODE (see
  CGAL::QGLViewer::toggleCameraMode()) keyboard shortcut (default is 'Space').

  <h3>Other functionalities</h3>

  The type() of the Camera can be Camera::ORTHOGRAPHIC or Camera::PERSPECTIVE
  (see Type()). fieldOfView() is meaningless with Camera::ORTHOGRAPHIC.

  The near and far planes of the Camera are fitted to the scene and determined
  from CGAL::QGLViewer::sceneRadius(), CGAL::QGLViewer::sceneCenter() and
  zClippingCoefficient() by the zNear() and zFar() methods. Reasonable values on
  the scene extends hence have to be provided to the CGAL::QGLViewer in order for the
  Camera to correctly display the scene. High level positioning methods also use
  this information (showEntireScene(), centerScene()...).

  A Camera holds KeyFrameInterpolator that can be used to save Camera positions
  and paths. You can interactively addKeyFrameToPath() to a given path using the
  default \c Alt+F[1-12] shortcuts. Use playPath() to make the Camera follow the
  path (default shortcut is F[1-12]). See the <a
  href="../keyboard.html">keyboard page</a> for details on key customization.

  Use cameraCoordinatesOf() and worldCoordinatesOf() to convert to and from the
  Camera frame() coordinate system. projectedCoordinatesOf() and
  unprojectedCoordinatesOf() will convert from screen to 3D coordinates.
  convertClickToLine() is very useful for analytical object selection.



  A Camera can also be used outside of a CGAL::QGLViewer or even without OpenGL for
  its coordinate system conversion capabilities. Note however that some of them
  explicitly rely on the presence of a Z-buffer. \nosubgrouping */
class CGAL_QT_EXPORT Camera : public QObject {
#ifndef DOXYGEN
  friend class ::CGAL::QGLViewer;
#endif

  Q_OBJECT

public:
  Camera(QObject *parent);
  virtual ~Camera();

  Camera(const Camera &camera);
  Camera &operator=(const Camera &camera);

  /*! Enumerates the two possible types of Camera.

  See type() and setType(). This type mainly defines different Camera projection
  matrix (see loadProjectionMatrix()). Many other methods (pointUnderPixel(),
  convertClickToLine(), projectedCoordinatesOf(), pixelGLRatio()...) are
  affected by this Type. */
  enum Type { PERSPECTIVE, ORTHOGRAPHIC };

  /*! @name Position and orientation */
  //@{
public:
  Vec position() const;
  Vec upVector() const;
  Vec viewDirection() const;
  Vec rightVector() const;
  Quaternion orientation() const;

  void setFromModelViewMatrix(const GLdouble *const modelViewMatrix);
  void setFromProjectionMatrix(const qreal matrix[12]);

public Q_SLOTS:
  void setPosition(const Vec &pos);
  void setOrientation(const Quaternion &q);
  void setOrientation(qreal theta, qreal phi);
  void setUpVector(const Vec &up, bool noMove = true);
  void setViewDirection(const Vec &direction);
  //@}

  /*! @name Positioning tools */
  //@{
public Q_SLOTS:
  void lookAt(const Vec &target);
  void showEntireScene();
  void fitSphere(const Vec &center, qreal radius);
  void fitBoundingBox(const Vec &min, const Vec &max);
  void fitScreenRegion(const QRect &rectangle);
  void centerScene();
  void interpolateToZoomOnPixel(const QPoint &pixel);
  void interpolateToFitScene();
  void interpolateTo(const Frame &fr, qreal duration);
  //@}

  /*! @name Frustum */
  //@{
public:
  /*! Returns the Camera::Type of the Camera.

  Set by setType(). Mainly used by loadProjectionMatrix().

  A Camera::PERSPECTIVE Camera uses a classical projection mainly defined by its
  fieldOfView().

  With a Camera::ORTHOGRAPHIC type(), the fieldOfView() is meaningless and the
  width and height of the Camera frustum are inferred from the distance to the
  pivotPoint() using getOrthoWidthHeight().

  Both types use zNear() and zFar() (to define their clipping planes) and
  aspectRatio() (for frustum shape). */
  Type type() const { return type_; }

  /*! Returns the vertical field of view of the Camera (in radians).

  Value is set using setFieldOfView(). Default value is pi/4 radians. This value
  is meaningless if the Camera type() is Camera::ORTHOGRAPHIC.

  The field of view corresponds the one used in \c gluPerspective (see manual).
  It sets the Y (vertical) aperture of the Camera. The X (horizontal) angle is
  inferred from the window aspect ratio (see aspectRatio() and
  horizontalFieldOfView()).

  Use setFOVToFitScene() to adapt the fieldOfView() to a given scene. */
  qreal fieldOfView() const { return fieldOfView_; }

  /*! Returns the horizontal field of view of the Camera (in radians).

  Value is set using setHorizontalFieldOfView() or setFieldOfView(). These
  values are always linked by: \code horizontalFieldOfView() = 2.0 * atan (
  tan(fieldOfView()/2.0) * aspectRatio() ). \endcode */
  qreal horizontalFieldOfView() const;

  /*! Returns the Camera aspect ratio defined by screenWidth() / screenHeight().

  When the Camera is attached to a CGAL::QGLViewer, these values and hence the
  aspectRatio() are automatically fitted to the viewer's window aspect ratio
  using setScreenWidthAndHeight(). */
  qreal aspectRatio() const {
    return screenWidth_ / static_cast<qreal>(screenHeight_);
  }
  /*! Returns the width (in pixels) of the Camera screen.

  Set using setScreenWidthAndHeight(). This value is automatically fitted to the
  CGAL::QGLViewer's window dimensions when the Camera is attached to a CGAL::QGLViewer. See
  also QOpenGLWidget::width() */
  int screenWidth() const { return screenWidth_; }
  /*! Returns the height (in pixels) of the Camera screen.

  Set using setScreenWidthAndHeight(). This value is automatically fitted to the
  CGAL::QGLViewer's window dimensions when the Camera is attached to a CGAL::QGLViewer. See
  also QOpenGLWidget::height() */
  int screenHeight() const { return screenHeight_; }
  qreal devicePixelRatio() const { return devicePixelRatio_; }
  void getViewport(GLint viewport[4]) const;
  qreal pixelGLRatio(const Vec &position) const;

  /*! Returns the coefficient which is used to set zNear() when the Camera is
  inside the sphere defined by sceneCenter() and zClippingCoefficient() *
  sceneRadius().

  In that case, the zNear() value is set to zNearCoefficient() *
  zClippingCoefficient() * sceneRadius(). See the zNear() documentation for
  details.

  Default value is 0.005, which is appropriate for most applications. In case
  you need a high dynamic ZBuffer precision, you can increase this value (~0.1).
  A lower value will prevent clipping of very close objects at the expense of a
  worst Z precision.

  Only meaningful when Camera type is Camera::PERSPECTIVE. */
  qreal zNearCoefficient() const { return zNearCoef_; }
  /*! Returns the coefficient used to position the near and far clipping planes.

  The near (resp. far) clipping plane is positioned at a distance equal to
  zClippingCoefficient() * sceneRadius() in front of (resp. behind) the
  sceneCenter(). This guarantees an optimal use of the z-buffer range and
  minimizes aliasing. See the zNear() and zFar() documentations.

  Default value is square root of 3.0 (so that a cube of size sceneRadius() is
  not clipped).

  However, since the sceneRadius() is used for other purposes (see
  showEntireScene(), flySpeed(),
  ...) and you may want to change this value to define more precisely the
  location of the clipping planes. See also zNearCoefficient().

  For a total control on clipping planes' positions, an other option is to
  overload the zNear() and zFar() methods. See the <a
  href="../examples/standardCamera.html">standardCamera example</a>.

  \attention When CGAL::QGLViewer::cameraPathAreEdited(), this value is set to 5.0 so
  that the Camera paths are not clipped. The previous zClippingCoefficient()
  value is restored back when you leave this mode. */
  qreal zClippingCoefficient() const { return zClippingCoef_; }

  virtual qreal zNear() const;
  virtual qreal zFar() const;
  virtual void getOrthoWidthHeight(GLdouble &halfWidth,
                                   GLdouble &halfHeight) const;
  void getFrustumPlanesCoefficients(GLdouble coef[6][4]) const;

public Q_SLOTS:
  void setType(Type type);

  void setFieldOfView(qreal fov);

  /*! Sets the horizontalFieldOfView() of the Camera (in radians).

  horizontalFieldOfView() and fieldOfView() are linked by the aspectRatio().
  This method actually calls setFieldOfView(( 2.0 * atan (tan(hfov / 2.0) /
  aspectRatio()) )) so that a call to horizontalFieldOfView() returns the
  expected value. */
  void setHorizontalFieldOfView(qreal hfov);

  void setFOVToFitScene();

  /*! Defines the Camera aspectRatio().

  This value is actually inferred from the screenWidth() / screenHeight() ratio.
  You should use setScreenWidthAndHeight() instead.

  This method might however be convenient when the Camera is not associated with
  a CGAL::QGLViewer. It actually sets the screenHeight() to 100 and the screenWidth()
  accordingly. See also setFOVToFitScene().

  \note If you absolutely need an aspectRatio() that does not correspond to your
  viewer's window dimensions, overload loadProjectionMatrix() or multiply the
  created GL_PROJECTION matrix by a scaled diagonal matrix in your
  CGAL::QGLViewer::draw() method. */
  void setAspectRatio(qreal aspect) {
    setScreenWidthAndHeight(int(100.0 * aspect), 100);
  }

  void setScreenWidthAndHeight(int width, int height, qreal devicePixelRatio = 1.0);
  /*! Sets the zNearCoefficient() value. */
  void setZNearCoefficient(qreal coef) {
    zNearCoef_ = coef;
    projectionMatrixIsUpToDate_ = false;
  }
  /*! Sets the zClippingCoefficient() value. */
  void setZClippingCoefficient(qreal coef) {
    zClippingCoef_ = coef;
    projectionMatrixIsUpToDate_ = false;
  }
  /*! Sets the zNear value in orthographic mode. */
  void setOrthoZNear(qreal z)
  {
    m_zMin = z;
  }
  /*! Returns the zNear value in orthographic mode*/
  qreal orthoZNear()
  {
    return m_zMin;
  }
  //@}

  /*! @name Scene radius and center */
  //@{
public:
  /*! Returns the radius of the scene observed by the Camera.

  You need to provide such an approximation of the scene dimensions so that the
  Camera can adapt its zNear() and zFar() values. See the sceneCenter()
  documentation.

  See also setSceneBoundingBox().

  Note that CGAL::QGLViewer::sceneRadius() (resp. CGAL::QGLViewer::setSceneRadius()) simply
  call this method (resp. setSceneRadius()) on its associated
  CGAL::QGLViewer::camera(). */
  qreal sceneRadius() const { return sceneRadius_; }

  /*! Returns the position of the scene center, defined in the world coordinate
  system.

  The scene observed by the Camera should be roughly centered on this position,
  and included in a sceneRadius() sphere. This approximate description of the
  scene permits a zNear() and zFar() clipping planes definition, and allows
  convenient positioning methods such as showEntireScene().

  Default value is (0,0,0) (world origin). Use setSceneCenter() to change it.
  See also setSceneBoundingBox().

  Note that CGAL::QGLViewer::sceneCenter() (resp. CGAL::QGLViewer::setSceneCenter()) simply
  calls this method (resp. setSceneCenter()) on its associated
  CGAL::QGLViewer::camera(). */
  Vec sceneCenter() const { return sceneCenter_; }
  qreal distanceToSceneCenter() const;

public Q_SLOTS:
  void setSceneRadius(qreal radius);
  void setSceneCenter(const Vec &center);
  bool setSceneCenterFromPixel(const QPoint &pixel);
  void setSceneBoundingBox(const Vec &min, const Vec &max);
  //@}

  /*! @name Pivot Point */
  //@{
public Q_SLOTS:
  void setPivotPoint(const Vec &point);
  bool setPivotPointFromPixel(const QPoint &pixel);

public:
  Vec pivotPoint() const;

  //@}

  /*! @name Associated frame */
  //@{
public:
  /*! Returns the ManipulatedCameraFrame attached to the Camera.

  This ManipulatedCameraFrame defines its position() and orientation() and can
  translate mouse events into Camera displacement. Set using setFrame(). */
  ManipulatedCameraFrame *frame() const { return frame_; }
public Q_SLOTS:
  void setFrame(ManipulatedCameraFrame *const mcf);
  //@}

  /*! @name KeyFramed paths */
  //@{
public:
  KeyFrameInterpolator *keyFrameInterpolator(unsigned int i) const;

public Q_SLOTS:
  void setKeyFrameInterpolator(unsigned int i, KeyFrameInterpolator *const kfi);

  virtual void addKeyFrameToPath(unsigned int i);
  virtual void playPath(unsigned int i);
  virtual void deletePath(unsigned int i);
  virtual void resetPath(unsigned int i);
  //@}

  /*! @name OpenGL matrices */
  //@{
public:
  virtual void loadProjectionMatrix(bool reset = true) const;
  virtual void loadModelViewMatrix(bool reset = true) const;
  void computeProjectionMatrix() const;
  void computeModelViewMatrix() const;
  //!Sets the frustum according to the current type of the camera
  //! (PERSPECTIVE or ORTHOGRAPHIC) in this order :
  //! left, right, top, bottom, near, far
  void setFrustum(double frustum[6]);
  //!Fills `frustum` from the current frustum of the camera according
  //! to the current type (PERSPECTIVE or ORTHOGRAPHIC) in this order :
  //! left, right, top, bottom, near, far
  void getFrustum(double frustum[6]);
  void getProjectionMatrix(GLfloat m[16]) const;
  void getProjectionMatrix(GLdouble m[16]) const;

  void getModelViewMatrix(GLfloat m[16]) const;
  void getModelViewMatrix(GLdouble m[16]) const;

  void getModelViewProjectionMatrix(GLfloat m[16]) const;
  void getModelViewProjectionMatrix(GLdouble m[16]) const;
//@}

  /*! @name World to Camera coordinate systems conversions */
  //@{
public:
  Vec cameraCoordinatesOf(const Vec &src) const;
  Vec worldCoordinatesOf(const Vec &src) const;
  void getCameraCoordinatesOf(const qreal src[3], qreal res[3]) const;
  void getWorldCoordinatesOf(const qreal src[3], qreal res[3]) const;
  //@}

  /*! @name 2D screen to 3D world coordinate systems conversions */
  //@{
public:
  Vec projectedCoordinatesOf(const Vec &src, const Frame *frame = nullptr) const;
  Vec unprojectedCoordinatesOf(const Vec &src, const Frame *frame = nullptr) const;
  void getProjectedCoordinatesOf(const qreal src[3], qreal res[3],
                                 const Frame *frame = nullptr) const;
  void getUnprojectedCoordinatesOf(const qreal src[3], qreal res[3],
                                   const Frame *frame = nullptr) const;
  void convertClickToLine(const QPoint &pixel, Vec &orig, Vec &dir) const;
  Vec pointUnderPixel(const QPoint &pixel, bool &found) const;
  //@}

  /*! @name Fly speed */
  //@{
public:
  qreal flySpeed() const;
public Q_SLOTS:
  void setFlySpeed(qreal speed);
  //@}

private Q_SLOTS:
  void onFrameModified();

private:
  QOpenGLFunctions_2_1* gl() const{ return dynamic_cast<QOpenGLFunctions_2_1*>(parent()); }
  // F r a m e
  ManipulatedCameraFrame *frame_;

  // C a m e r a   p a r a m e t e r s
  int screenWidth_, screenHeight_; // size of the window, in pixels
  qreal devicePixelRatio_;
  qreal fieldOfView_;              // in radians
  Vec sceneCenter_;
  qreal sceneRadius_; // OpenGL units
  qreal zNearCoef_;
  qreal zClippingCoef_;
  qreal orthoCoef_;
  Type type_;                            // PERSPECTIVE or ORTHOGRAPHIC
  mutable GLdouble modelViewMatrix_[16]; // Buffered model view matrix.
  mutable bool modelViewMatrixIsUpToDate_;
  mutable GLdouble projectionMatrix_[16]; // Buffered projection matrix.
  mutable bool projectionMatrixIsUpToDate_;
  qreal m_zMin; //USed for near plane in orthographic projection.

  // S t e r e o   p a r a m e t e r s
  qreal IODistance_;          // inter-ocular distance, in meters
  qreal focusDistance_;       // in scene units
  qreal physicalScreenWidth_; // in meters

  // P o i n t s   o f   V i e w s   a n d   K e y F r a m e s
  QMap<unsigned int, KeyFrameInterpolator *> kfi_;
  KeyFrameInterpolator *interpolationKfi_;
};

inline void read_pixel(const QPoint &pixel, QOpenGLFunctions *p,
                        const Camera *camera, GLenum format, GLenum type,
                        GLvoid *pixel_data) {
  const auto pixel_ratio = camera->devicePixelRatio();
  p->glReadPixels(pixel.x() * pixel_ratio,
                  (camera->screenHeight() - pixel.y()) * pixel_ratio - 1, 1, 1,
                  format, type, pixel_data);
}

inline auto read_pixel_as_float_rgb(const QPoint &pixel, QOpenGLFunctions *p,
                                    const Camera *camera) {
  std::array<float, 3> res;
  read_pixel(pixel, p, camera, GL_RGB, GL_FLOAT, res.data());
  return res;
}

inline auto read_pixel_as_ubyte_rgba(const QPoint &pixel, QOpenGLFunctions *p,
                                    const Camera *camera) {
  std::array<GLubyte, 4> res;
  read_pixel(pixel, p, camera, GL_RGBA, GL_UNSIGNED_BYTE, res.data());
  return res;
}

inline float read_depth_under_pixel(const QPoint &pixel, QOpenGLFunctions *p,
                                    const Camera *camera) {
  float depth = 2.0f;
  read_pixel(pixel, p, camera, GL_DEPTH_COMPONENT, GL_FLOAT, &depth);
  return depth;
}

} // namespace qglviewer
} //CGAL
#endif // QGLVIEWER_CAMERA_H

