flightgear/src/Main/viewer.cxx

// viewer.cxx -- class for managing a viewer in the flightgear world.
//
// Written by Curtis Olson, started August 1997.
//                          overhaul started October 2000.
//
// Copyright (C) 1997 - 2000  Curtis L. Olson  - curt@flightgear.org
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//
// $Id$


#include <simgear/compiler.h>

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <simgear/debug/logstream.hxx>
#include <simgear/constants.h>
#include <simgear/math/point3d.hxx>
#include <simgear/math/polar3d.hxx>
#include <simgear/math/sg_geodesy.hxx>

#include <Scenery/scenery.hxx>

#include "viewer.hxx"



////////////////////////////////////////////////////////////////////////
// Implementation of FGViewPoint.
////////////////////////////////////////////////////////////////////////

FGViewPoint::FGViewPoint ()
  : _dirty(true),
    _lon_deg(0),
    _lat_deg(0),
    _alt_ft(0)
{
}

FGViewPoint::~FGViewPoint ()
{
}

void
FGViewPoint::setPosition (double lon_deg, double lat_deg, double alt_ft)
{
  _dirty = true;
  _lon_deg = lon_deg;
  _lat_deg = lat_deg;
  _alt_ft = alt_ft;
}

const double *
FGViewPoint::getAbsoluteViewPos () const
{
  if (_dirty)
    recalc();
  return _absolute_view_pos;
}

const float *
FGViewPoint::getRelativeViewPos () const
{
  if (_dirty)
    recalc();
  return _relative_view_pos;
}

const float *
FGViewPoint::getZeroElevViewPos () const
{
  if (_dirty)
    recalc();
  return _zero_elev_view_pos;
}

void
FGViewPoint::recalc () const
{
  double sea_level_radius_m;
  double lat_geoc_rad;

				// Convert from geodetic to geocentric
				// coordinates.
  sgGeodToGeoc(_lat_deg * SGD_DEGREES_TO_RADIANS,
	       _alt_ft * SG_FEET_TO_METER,
	       &sea_level_radius_m,
	       &lat_geoc_rad);

				// Calculate the cartesian coordinates
				// of point directly below at sea level.
  Point3D p = Point3D(_lon_deg * SG_DEGREES_TO_RADIANS,
		      lat_geoc_rad,
		      sea_level_radius_m);
  Point3D tmp = sgPolarToCart3d(p) - scenery.get_next_center();
  sgSetVec3(_zero_elev_view_pos, tmp[0], tmp[1], tmp[2]);

				// Calculate the absolute view position
				// in fgfs coordinates.
  p.setz(p.radius() + _alt_ft * SG_FEET_TO_METER);
  tmp = sgPolarToCart3d(p);
  sgdSetVec3(_absolute_view_pos, tmp[0], tmp[1], tmp[2]);

				// Calculate the relative view position
				// from the scenery center.
  sgdVec3 scenery_center;
  sgdSetVec3(scenery_center,
	     scenery.get_next_center().x(),
	     scenery.get_next_center().y(),
	     scenery.get_next_center().z());
  sgdVec3 view_pos;
  sgdSubVec3(view_pos, _absolute_view_pos, scenery_center);
  sgSetVec3(_relative_view_pos, view_pos);
}



////////////////////////////////////////////////////////////////////////
// Implementation of FGViewer.
////////////////////////////////////////////////////////////////////////

// Constructor
FGViewer::FGViewer( void ):
    scalingType(FG_SCALING_MAX),
    fov(55.0),
    view_offset(0.0),
    goal_view_offset(0.0),
    view_tilt(0.0),
    goal_view_tilt(0.0)
{
    sgSetVec3( pilot_offset, 0.0, 0.0, 0.0 );
    sgdZeroVec3(geod_view_pos);
    sgdZeroVec3(abs_view_pos);
    sea_level_radius = SG_EQUATORIAL_RADIUS_M; 
    //a reasonable guess for init, so that the math doesn't blow up
}


// Destructor
FGViewer::~FGViewer( void ) {
}

void
FGViewer::init ()
{
}

void
FGViewer::bind ()
{
}

void
FGViewer::unbind ()
{
}

double
FGViewer::get_h_fov()
{
    switch (scalingType) {
    case FG_SCALING_WIDTH:  // h_fov == fov
	return fov;
    case FG_SCALING_MAX:
	if (aspect_ratio < 1.0) {
	    // h_fov == fov
	    return fov;
	} else {
	    // v_fov == fov
	    return atan(tan(fov/2 * SG_DEGREES_TO_RADIANS) / aspect_ratio) *
		SG_RADIANS_TO_DEGREES * 2;
	}
    default:
	assert(false);
    }
}

double
FGViewer::get_v_fov()
{
    switch (scalingType) {
    case FG_SCALING_WIDTH:  // h_fov == fov
	return atan(tan(fov/2 * SG_DEGREES_TO_RADIANS) * aspect_ratio) *
	    SG_RADIANS_TO_DEGREES * 2;
    case FG_SCALING_MAX:
	if (aspect_ratio < 1.0) {
	    // h_fov == fov
	    return atan(tan(fov/2 * SG_DEGREES_TO_RADIANS) * aspect_ratio) *
		SG_RADIANS_TO_DEGREES * 2;
	} else {
	    // v_fov == fov
	    return fov;
	}
    default:
	assert(false);
    }
}

void
FGViewer::update (int dt)
{
  int i;
  for ( i = 0; i < dt; i++ ) {
    if ( fabs(get_goal_view_offset() - get_view_offset()) < 0.05 ) {
      set_view_offset( get_goal_view_offset() );
      break;
    } else {
      // move current_view.view_offset towards
      // current_view.goal_view_offset
      if ( get_goal_view_offset() > get_view_offset() )
	{
	  if ( get_goal_view_offset() - get_view_offset() < SGD_PI ){
	    inc_view_offset( 0.01 );
	  } else {
	    inc_view_offset( -0.01 );
	  }
	} else {
	  if ( get_view_offset() - get_goal_view_offset() < SGD_PI ){
	    inc_view_offset( -0.01 );
	  } else {
	    inc_view_offset( 0.01 );
	  }
	}
      if ( get_view_offset() > SGD_2PI ) {
	inc_view_offset( -SGD_2PI );
      } else if ( get_view_offset() < 0 ) {
	inc_view_offset( SGD_2PI );
      }
    }
  }

  for ( i = 0; i < dt; i++ ) {
    if ( fabs(get_goal_view_tilt() - get_view_tilt()) < 0.05 ) {
      set_view_tilt( get_goal_view_tilt() );
      break;
    } else {
      // move current_view.view_tilt towards
      // current_view.goal_view_tilt
      if ( get_goal_view_tilt() > get_view_tilt() )
	{
	  if ( get_goal_view_tilt() - get_view_tilt() < SGD_PI ){
	    inc_view_tilt( 0.01 );
	  } else {
	    inc_view_tilt( -0.01 );
	  }
	} else {
	  if ( get_view_tilt() - get_goal_view_tilt() < SGD_PI ){
	    inc_view_tilt( -0.01 );
	  } else {
	    inc_view_tilt( 0.01 );
	  }
	}
      if ( get_view_tilt() > SGD_2PI ) {
	inc_view_tilt( -SGD_2PI );
      } else if ( get_view_tilt() < 0 ) {
	inc_view_tilt( SGD_2PI );
      }
    }
  }
}