/* SPDX-FileCopyrightText: 2008-2022 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

/** \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 <cstdio>
#include <cstring>

#include "Silhouette.h"
#include "SilhouetteGeomEngine.h"

#include "../geometry/GeomUtils.h"

#include "BLI_sys_types.h"

#include "BKE_global.hh"

using namespace std;

namespace Freestyle {

Vec3r SilhouetteGeomEngine::_Viewpoint = Vec3r(0, 0, 0);
real SilhouetteGeomEngine::_translation[3] = {0, 0, 0};
real SilhouetteGeomEngine::_modelViewMatrix[4][4] = {
    {1, 0, 0, 0},
    {0, 1, 0, 0},
    {0, 0, 1, 0},
    {0, 0, 0, 1},
};
real SilhouetteGeomEngine::_projectionMatrix[4][4] = {
    {1, 0, 0, 0},
    {0, 1, 0, 0},
    {0, 0, 1, 0},
    {0, 0, 0, 1},
};
real SilhouetteGeomEngine::_transform[4][4] = {
    {1, 0, 0, 0},
    {0, 1, 0, 0},
    {0, 0, 1, 0},
    {0, 0, 0, 1},
};
int SilhouetteGeomEngine::_viewport[4] = {1, 1, 1, 1};
real SilhouetteGeomEngine::_Focal = 0.0;

real SilhouetteGeomEngine::_glProjectionMatrix[4][4] = {
    {1, 0, 0, 0},
    {0, 1, 0, 0},
    {0, 0, 1, 0},
    {0, 0, 0, 1},
};
real SilhouetteGeomEngine::_glModelViewMatrix[4][4] = {
    {1, 0, 0, 0},
    {0, 1, 0, 0},
    {0, 0, 1, 0},
    {0, 0, 0, 1},
};
real SilhouetteGeomEngine::_znear = 0.0;
real SilhouetteGeomEngine::_zfar = 100.0;
bool SilhouetteGeomEngine::_isOrthographicProjection = false;

SilhouetteGeomEngine *SilhouetteGeomEngine::_pInstance = nullptr;

void SilhouetteGeomEngine::setTransform(const real iModelViewMatrix[4][4],
                                        const real iProjectionMatrix[4][4],
                                        const int iViewport[4],
                                        real iFocal)
{
  uint i, j;
  _translation[0] = iModelViewMatrix[3][0];
  _translation[1] = iModelViewMatrix[3][1];
  _translation[2] = iModelViewMatrix[3][2];

  for (i = 0; i < 4; i++) {
    for (j = 0; j < 4; j++) {
      _modelViewMatrix[i][j] = iModelViewMatrix[j][i];
      _glModelViewMatrix[i][j] = iModelViewMatrix[i][j];
    }
  }

  for (i = 0; i < 4; i++) {
    for (j = 0; j < 4; j++) {
      _projectionMatrix[i][j] = iProjectionMatrix[j][i];
      _glProjectionMatrix[i][j] = iProjectionMatrix[i][j];
    }
  }

  for (i = 0; i < 4; i++) {
    for (j = 0; j < 4; j++) {
      _transform[i][j] = 0;
      for (uint k = 0; k < 4; k++) {
        _transform[i][j] += _projectionMatrix[i][k] * _modelViewMatrix[k][j];
      }
    }
  }

  for (i = 0; i < 4; i++) {
    _viewport[i] = iViewport[i];
  }
  _Focal = iFocal;

  _isOrthographicProjection = (iProjectionMatrix[3][3] != 0.0);
}

void SilhouetteGeomEngine::setFrustum(real iZNear, real iZFar)
{
  _znear = iZNear;
  _zfar = iZFar;
}

void SilhouetteGeomEngine::retrieveViewport(int viewport[4])
{
  memcpy(viewport, _viewport, sizeof(int[4]));
}

void SilhouetteGeomEngine::ProjectSilhouette(vector<SVertex *> &ioVertices)
{
  Vec3r newPoint;
  vector<SVertex *>::iterator sv, svend;
  for (sv = ioVertices.begin(), svend = ioVertices.end(); sv != svend; sv++) {
    GeomUtils::fromWorldToImage(
        (*sv)->point3D(), newPoint, _modelViewMatrix, _projectionMatrix, _viewport);
    (*sv)->setPoint2D(newPoint);
  }
}

void SilhouetteGeomEngine::ProjectSilhouette(SVertex *ioVertex)
{
  Vec3r newPoint;
  GeomUtils::fromWorldToImage(
      ioVertex->point3D(), newPoint, _modelViewMatrix, _projectionMatrix, _viewport);
  ioVertex->setPoint2D(newPoint);
}

real SilhouetteGeomEngine::ImageToWorldParameter(FEdge *fe, real t)
{
  if (_isOrthographicProjection) {
    return t;
  }

  // we need to compute for each parameter t the corresponding parameter T which gives the
  // intersection in 3D.
  real T;

  // suffix w for world, c for camera, r for retina, i for image
  Vec3r Aw = (fe)->vertexA()->point3D();
  Vec3r Bw = (fe)->vertexB()->point3D();
  Vec3r Ac, Bc;
  GeomUtils::fromWorldToCamera(Aw, Ac, _modelViewMatrix);
  GeomUtils::fromWorldToCamera(Bw, Bc, _modelViewMatrix);
  Vec3r ABc = Bc - Ac;
#if 0
  if (G.debug & G_DEBUG_FREESTYLE) {
    cout << "Ac " << Ac << endl;
    cout << "Bc " << Bc << endl;
    cout << "ABc " << ABc << endl;
  }
#endif
  Vec3r Ai = (fe)->vertexA()->point2D();
  Vec3r Bi = (fe)->vertexB()->point2D();
  Vec3r Ii = Ai + t * (Bi - Ai);  // the intersection point in the 2D image space
  Vec3r Ir, Ic;
  GeomUtils::fromImageToRetina(Ii, Ir, _viewport);

  real alpha, beta, denom;
  real m11 = _projectionMatrix[0][0];
  real m13 = _projectionMatrix[0][2];
  real m22 = _projectionMatrix[1][1];
  real m23 = _projectionMatrix[1][2];

  if (fabs(ABc[0]) > 1.0e-6) {
    alpha = ABc[2] / ABc[0];
    beta = Ac[2] - alpha * Ac[0];
    denom = alpha * (Ir[0] + m13) + m11;
    if (fabs(denom) < 1.0e-6) {
      goto iter;
    }
    Ic[0] = -beta * (Ir[0] + m13) / denom;
#if 0
    Ic[1] = -(Ir[1] + m23) * (alpha * Ic[0] + beta) / m22;
    Ic[2] = alpha * (Ic[0] - Ac[0]) + Ac[2];
#endif
    T = (Ic[0] - Ac[0]) / ABc[0];
  }
  else if (fabs(ABc[1]) > 1.0e-6) {
    alpha = ABc[2] / ABc[1];
    beta = Ac[2] - alpha * Ac[1];
    denom = alpha * (Ir[1] + m23) + m22;
    if (fabs(denom) < 1.0e-6) {
      goto iter;
    }
    Ic[1] = -beta * (Ir[1] + m23) / denom;
#if 0
    Ic[0] = -(Ir[0] + m13) * (alpha * Ic[1] + beta) / m11;
    Ic[2] = alpha * (Ic[1] - Ac[1]) + Ac[2];
#endif
    T = (Ic[1] - Ac[1]) / ABc[1];
  }
  else {
  iter:
    bool x_coords, less_than;
    if (fabs(Bi[0] - Ai[0]) > 1.0e-6) {
      x_coords = true;
      less_than = Ai[0] < Bi[0];
    }
    else {
      x_coords = false;
      less_than = Ai[1] < Bi[1];
    }
    Vec3r Pc, Pr, Pi;
    real T_sta = 0.0;
    real T_end = 1.0;
    real delta_x, delta_y, dist, dist_threshold = 1.0e-6;
    int i, max_iters = 100;
    for (i = 0; i < max_iters; i++) {
      T = T_sta + 0.5 * (T_end - T_sta);
      Pc = Ac + T * ABc;
      GeomUtils::fromCameraToRetina(Pc, Pr, _projectionMatrix);
      GeomUtils::fromRetinaToImage(Pr, Pi, _viewport);
      delta_x = Ii[0] - Pi[0];
      delta_y = Ii[1] - Pi[1];
      dist = sqrt(delta_x * delta_x + delta_y * delta_y);
      if (dist < dist_threshold) {
        break;
      }
      if (x_coords) {
        if (less_than) {
          if (Pi[0] < Ii[0]) {
            T_sta = T;
          }
          else {
            T_end = T;
          }
        }
        else {
          if (Pi[0] > Ii[0]) {
            T_sta = T;
          }
          else {
            T_end = T;
          }
        }
      }
      else {
        if (less_than) {
          if (Pi[1] < Ii[1]) {
            T_sta = T;
          }
          else {
            T_end = T;
          }
        }
        else {
          if (Pi[1] > Ii[1]) {
            T_sta = T;
          }
          else {
            T_end = T;
          }
        }
      }
    }
#if 0
    if (G.debug & G_DEBUG_FREESTYLE) {
      cout << "SilhouetteGeomEngine::ImageToWorldParameter(): #iters = " << i
           << ", dist = " << dist << "\n";
    }
#endif
    if (i == max_iters && G.debug & G_DEBUG_FREESTYLE) {
      cout << "SilhouetteGeomEngine::ImageToWorldParameter(): reached to max_iters (dist = "
           << dist << ")\n";
    }
  }

  return T;
}

Vec3r SilhouetteGeomEngine::WorldToImage(const Vec3r &M)
{
  Vec3r newPoint;
  GeomUtils::fromWorldToImage(M, newPoint, _transform, _viewport);
  return newPoint;
}

Vec3r SilhouetteGeomEngine::CameraToImage(const Vec3r &M)
{
  Vec3r newPoint, p;
  GeomUtils::fromCameraToRetina(M, p, _projectionMatrix);
  GeomUtils::fromRetinaToImage(p, newPoint, _viewport);
  return newPoint;
}

} /* namespace Freestyle */
