/* SPDX-License-Identifier: GPL-2.0-or-later */

#pragma once

/** \file
 * \ingroup freestyle
 * \brief Class to perform all geometric operations dedicated to silhouette. That, for example,
 * implies that this geom engine has as member data the viewpoint, transformations, projections...
 */

#include <vector>

#include "../geometry/Geom.h"

#include "../system/FreestyleConfig.h"

#ifdef WITH_CXX_GUARDEDALLOC
#  include "MEM_guardedalloc.h"
#endif

namespace Freestyle {

using namespace Geometry;

class SVertex;
class FEdge;

class SilhouetteGeomEngine {
 private:
  // The viewpoint under which the silhouette has to be computed
  static Vec3r _Viewpoint;
  static real _translation[3];
  // the model view matrix (_modelViewMatrix[i][j] means element of line i and column j)
  static real _modelViewMatrix[4][4];
  // the projection matrix (_projectionMatrix[i][j] means element of line i and column j)
  static real _projectionMatrix[4][4];
  // the global transformation from world to screen (projection included)
  // (_transform[i][j] means element of line i and column j)
  static real _transform[4][4];
  // the viewport
  static int _viewport[4];
  static real _Focal;

  static real _znear;
  static real _zfar;

  // GL style (column major) projection matrix
  static real _glProjectionMatrix[4][4];
  // GL style (column major) model view matrix
  static real _glModelViewMatrix[4][4];

  static bool _isOrthographicProjection;

  static SilhouetteGeomEngine *_pInstance;

 public:
  /** retrieves an instance on the singleton */
  static SilhouetteGeomEngine *getInstance()
  {
    if (_pInstance == NULL) {
      _pInstance = new SilhouetteGeomEngine;
    }
    return _pInstance;
  }

  /** Sets the current viewpoint */
  static inline void setViewpoint(const Vec3r &ivp)
  {
    _Viewpoint = ivp;
  }

  /** Sets the current transformation
   *    iModelViewMatrix
   *      The 4x4 model view matrix, in column major order (openGL like).
   *    iProjection matrix
   *      The 4x4 projection matrix, in column major order (openGL like).
   *    iViewport
   *      The viewport. 4 real array: origin.x, origin.y, width, length
   *    iFocal
   *      The focal length
   */
  static void setTransform(const real iModelViewMatrix[4][4],
                           const real iProjectionMatrix[4][4],
                           const int iViewport[4],
                           real iFocal);

  /** Sets the current znear and zfar */
  static void setFrustum(real iZNear, real iZFar);

  /* accessors */
  static void retrieveViewport(int viewport[4]);

  /** Projects the silhouette in camera coordinates
   *  This method modifies the ioEdges passed as argument.
   *    ioVertices
   *      The vertices to project. It is modified during the operation.
   */
  static void ProjectSilhouette(std::vector<SVertex *> &ioVertices);
  static void ProjectSilhouette(SVertex *ioVertex);

  /** transforms the parameter t defining a 2D intersection for edge fe in order to obtain
   *  the parameter giving the corresponding 3D intersection.
   *  Returns the 3D parameter
   *    fe
   *      The edge
   *    t
   *      The parameter for the 2D intersection.
   */
  static real ImageToWorldParameter(FEdge *fe, real t);

  /** From world to image */
  static Vec3r WorldToImage(const Vec3r &M);

  /** From camera to image */
  static Vec3r CameraToImage(const Vec3r &M);

#ifdef WITH_CXX_GUARDEDALLOC
  MEM_CXX_CLASS_ALLOC_FUNCS("Freestyle:SilhouetteGeomEngine")
#endif
};

} /* namespace Freestyle */