#include <cmath>

#include "opengl.h"

#include "view.h"
#include "oct.h"

vector<GLuint> occ_query_objects;

static GLuint begin_occ_query ()
{
  GLuint id;

  if (occ_query_objects.size ())
    {
      id = *(occ_query_objects.end () - 1);
      occ_query_objects.pop_back ();
    }
  else
    glGenQueriesARB (1, &id);

  glBeginQueryARB (GL_SAMPLES_PASSED, id);
  return id;
}

inline void end_occ_query ()
{
  glEndQueryARB (GL_SAMPLES_PASSED);
}

static GLuint occ_query_result (GLuint id)
{
  GLuint count;

  glGetQueryObjectuivARB (id, GL_QUERY_RESULT, &count);
  occ_query_objects.push_back (id);

  return count;
}

view::view ()
: gamma(1.0)
{
}

view::~view ()
{
}

void view::begin_occ_query (recv_occ_query &recv, void *id)
{
  occ_queries.push_back (oq_data (&recv, ::begin_occ_query (), id));
}

void view::end_occ_query ()
{
  ::end_occ_query ();
}

bool view::may_draw (const entity *e)
{
  if (drawn.find (e) != drawn.end ())
    return false;

  drawn.insert (e);
  return true;
}

visibility_base *visible::get_visibility (view &ctx)
{
  view::visibility_map::iterator i = ctx.vismap.find (this);
  visibility_base *vs;

  if (i == ctx.vismap.end ())
    {
      vs = new_visibility ();
      ctx.vismap.insert (view::visibility_map::value_type (this, vs));
    }
  else
    {
      vs = i->second;

      if (vs->generation != ctx.generation)
        {
          if (vs->generation + 1 != ctx.generation)
            clear_visibility (vs);

          vs->generation = ctx.generation;
        }
    }

  return vs;

}

void view::reset_projection ()
{
  renormalize (orig, p);

  glViewport (0, 0, w, h);

  glMatrixMode (GL_PROJECTION);
  glLoadIdentity ();

  GLdouble aspect = (GLdouble)w/h;
  GLdouble ymax = z_near * tan (fov * (M_PI / 360.0));

  glFrustum (-ymax * aspect, ymax * aspect, -ymax, ymax, z_near, z_far);

  perspfact = z_near / ymax * 0.5 * (GLdouble)h;

  d = normalize (d);//D
  u = normalize (u);//D

  vec3 rz = -d;
  vec3 rx = cross (u, rz);
  vec3 ry = cross (rz, rx);

  matrix &m = projection;
  m(0,0) = rx.x; m(0,1) = rx.y; m(0,2) = rx.z; m(0,3) = 0;
  m(1,0) = ry.x; m(1,1) = ry.y; m(1,2) = ry.z; m(1,3) = 0;
  m(2,0) = rz.x; m(2,1) = rz.y; m(2,2) = rz.z; m(2,3) = 0;
  m(3,0) =    0; m(3,1) =    0; m(3,2) =    0; m(3,3) = 1;

  diagfact = abs (rz.x) + abs (rz.y) + abs (rz.z);
  //printf ("diagfact = %f\n", diagfact);
  diagfact = sqrtf (3.);//D WHY???

  glMultMatrixf (m);
  glTranslatef (-p.x, -p.y, -p.z);

  glGetFloatv (GL_PROJECTION_MATRIX, m);

  frustum.l = plane ( m(3,0) + m(0,0), m(3,1) + m(0,1), m(3,2) + m(0,2), m(3,3) + m(0,3) );
  frustum.r = plane ( m(3,0) - m(0,0), m(3,1) - m(0,1), m(3,2) - m(0,2), m(3,3) - m(0,3) );
  frustum.b = plane ( m(3,0) + m(1,0), m(3,1) + m(1,1), m(3,2) + m(1,2), m(3,3) + m(1,3) );
  frustum.t = plane ( m(3,0) - m(1,0), m(3,1) - m(1,1), m(3,2) - m(1,2), m(3,3) - m(1,3) );
  frustum.n = plane ( m(3,0) + m(2,0), m(3,1) + m(2,1), m(3,2) + m(2,2), m(3,3) + m(2,3) );
  frustum.f = plane ( m(3,0) - m(2,0), m(3,1) - m(2,1), m(3,2) - m(2,2), m(3,3) - m(2,3) );

  glMatrixMode (GL_MODELVIEW);
  glLoadIdentity ();
}

void view::begin ()
{
  generation++;

  glColorMask (1, 1, 1, 1);
  glDepthMask (1);
  glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  vislist.clear ();

  z_far = nz_far;
  c_far = nc_far;

  if (z_far < z_near)
    z_far = z_near * 2.;

  reset_projection ();

  nc_far = nz_far = z_near + 1.F;
  world.detect_visibility (*this);

  printf ("far %f cf %f CAM (%d,%d,%d)\n", z_far, c_far, orig.x, orig.y, orig.z);//D
}

void view::end ()
{
  vislist.clear ();
}

#define DEPTH_OFFSET (1. / (GLdouble)(1L << 16))

void view::pass (enum mode m)
{
  mode = m;

  glDisable (GL_ALPHA_TEST);
  glDisable (GL_BLEND);

  switch (mode)
    {
      case DEPTH:
        //glEnable (GL_POLYGON_OFFSET_FILL);
        //glPolygonOffset (0, 5);
        glDisable (GL_MINMAX);
        glDepthRange (DEPTH_OFFSET, 1.);
        glDepthFunc (GL_LESS);
        glEnable (GL_DEPTH_TEST);
        glColorMask (0, 0, 0, 0);
        glDepthMask (1);
        break;

      case POSTDEPTH:
        glEnable (GL_DEPTH_TEST);
        glDepthRange (DEPTH_OFFSET, 1.);
        glColorMask (0, 0, 0, 0);
        glDepthMask (0);
       
        // check occlusion queries
        for (vector<oq_data>::iterator i = occ_queries.begin (); i != occ_queries.end (); ++i)
          {
            occ_query oq(*this, i->data, ::occ_query_result (i->id));
            i->recv->event (oq);
          }

        occ_queries.clear ();

        break;

      case LIGHTED:
        glEnable (GL_MINMAX);
        glDepthRange (0., 1. - DEPTH_OFFSET);
        glDepthFunc (GL_LESS);
        glColorMask (1, 1, 1, 1);
        glDepthMask (0);
        break;
    }
  
  for (vector<octant *>::iterator i = vislist.begin (); i != vislist.end (); ++i)
    (*i)->display (*this);

  drawn.clear ();

#if 0
  if (mode == view::DEPTH)
    {
      glEnable (GL_DEPTH_CLAMP_NV);
      glDepthMask (0);
      glDepthFunc (GL_LESS);

      for (vector<octant *>::iterator i = farlist.begin (); i != farlist.end (); ++i)
        {
          begin_occ_query (**i);
          (*i)->draw_bbox (*this);
          end_occ_query ();
       }

      glDisable (GL_DEPTH_CLAMP_NV);
    }
#endif
}