#include <cmath>

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

draw_context::draw_context (view &v)
: v(v), l(0), mode(LIGHTED)
{
}

draw_context::~draw_context ()
{
}

bool draw_context::may_draw (entity_base *e)
{
  if (drawn.find (e) != drawn.end ())
    return false;

  drawn.insert (e);
  return true;
}

void view::draw (draw_context &ctx)
{

  if (ctx.mode == draw_context::DEPTH)
    {
      glEnable (GL_POLYGON_OFFSET_FILL);
      glPolygonOffset (0, 1);
      glDrawBuffer (GL_NONE);
      glDepthFunc (GL_LESS);
      glDisable (GL_LIGHTING);
    }
  else
    {
      glDisable (GL_POLYGON_OFFSET_FILL);
      glDrawBuffer (GL_BACK);
      glDepthFunc (GL_LEQUAL);
      glEnable (GL_LIGHTING);
    }
  
  glViewport (0, 0, w, h);

  glMatrixMode (GL_PROJECTION);
  glLoadIdentity ();

  GLdouble aspect = (GLdouble)w/h;
  GLdouble zNear = 0.001;
  GLdouble zFar = 100.;

  GLdouble ymax = zNear * tan (fov * (M_PI / 360.0));
  glFrustum (-ymax * aspect, ymax * aspect, -ymax, ymax, zNear, zFar);

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

  gl_matrix &m = ctx.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;

  glMultMatrixf ((GLfloat *)m.data);

  glMatrixMode (GL_MODELVIEW);
  glLoadIdentity ();
  glTranslatef (-p.x, -p.y, -p.z);

  world.draw (ctx);
}