1 // views.cxx -- data structures and routines for managing and view
4 // Written by Curtis Olson, started August 1997.
6 // Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
8 // This program is free software; you can redistribute it and/or
9 // modify it under the terms of the GNU General Public License as
10 // published by the Free Software Foundation; either version 2 of the
11 // License, or (at your option) any later version.
13 // This program is distributed in the hope that it will be useful, but
14 // WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 // General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 // (Log is kept at end of this file)
30 #include <Aircraft/aircraft.hxx>
31 #include <Cockpit/panel.hxx>
32 #include <Debug/logstream.hxx>
33 #include <Include/fg_constants.h>
34 #include <Math/mat3.h>
35 #include <Math/point3d.hxx>
36 #include <Math/polar3d.hxx>
37 #include <Math/vector.hxx>
38 #include <Scenery/scenery.hxx>
39 #include <Time/fg_time.hxx>
41 #include "options.hxx"
45 // Define following to extract various vectors directly
46 // from matrices we have allready computed
47 // rather then performing 'textbook algebra' to rederive them
48 // Norman Vine -- nhv@yahoo.com
49 // #define FG_VIEW_INLINE_OPTIMIZATIONS
51 // temporary (hopefully) hack
52 static int panel_hist = 0;
55 // specify code paths ... these are done as variable rather than
56 // #define's because down the road we may want to choose between them
57 // on the fly for different flight models ... this way magic carpet
58 // and external modes wouldn't need to recreate the LaRCsim matrices
61 static const bool use_larcsim_local_to_body = false;
64 // This is a record containing current view parameters
69 FGView::FGView( void ) {
74 // Initialize a view structure
75 void FGView::Init( void ) {
76 FG_LOG( FG_VIEW, FG_INFO, "Initializing View parameters" );
79 goal_view_offset = 0.0;
81 winWidth = current_options.get_xsize();
82 winHeight = current_options.get_ysize();
84 if ( ! current_options.get_panel_status() ) {
85 current_view.set_win_ratio( (GLfloat) winWidth / (GLfloat) winHeight );
87 current_view.set_win_ratio( (GLfloat) winWidth /
88 ((GLfloat) (winHeight)*0.4232) );
91 force_update_fov_math();
95 // Update the field of view coefficients
96 void FGView::UpdateFOV( const fgOPTIONS& o ) {
97 double fov, theta_x, theta_y;
101 // printf("win_ratio = %.2f\n", win_ratio);
102 // calculate sin() and cos() of fov / 2 in X direction;
103 theta_x = (fov * win_ratio * DEG_TO_RAD) / 2.0;
104 // printf("theta_x = %.2f\n", theta_x);
105 sin_fov_x = sin(theta_x);
106 cos_fov_x = cos(theta_x);
107 slope_x = -cos_fov_x / sin_fov_x;
108 // printf("slope_x = %.2f\n", slope_x);
110 // fov_x_clip and fov_y_clip convoluted algebraic simplification
111 // see code executed in tilemgr.cxx when USE_FAST_FOV_CLIP not
112 // defined Norman Vine -- nhv@yahoo.com
113 #if defined( USE_FAST_FOV_CLIP )
114 fov_x_clip = slope_x*cos_fov_x - sin_fov_x;
115 #endif // defined( USE_FAST_FOV_CLIP )
117 // calculate sin() and cos() of fov / 2 in Y direction;
118 theta_y = (fov * DEG_TO_RAD) / 2.0;
119 // printf("theta_y = %.2f\n", theta_y);
120 sin_fov_y = sin(theta_y);
121 cos_fov_y = cos(theta_y);
122 slope_y = cos_fov_y / sin_fov_y;
123 // printf("slope_y = %.2f\n", slope_y);
125 #if defined( USE_FAST_FOV_CLIP )
126 fov_y_clip = -(slope_y*cos_fov_y + sin_fov_y);
127 #endif // defined( USE_FAST_FOV_CLIP )
131 // Basically, this is a modified version of the Mesa gluLookAt()
132 // function that's been modified slightly so we can capture the
133 // result before sending it off to OpenGL land.
134 void FGView::LookAt( GLdouble eyex, GLdouble eyey, GLdouble eyez,
135 GLdouble centerx, GLdouble centery, GLdouble centerz,
136 GLdouble upx, GLdouble upy, GLdouble upz ) {
138 GLdouble x[3], y[3], z[3];
141 m = current_view.MODEL_VIEW;
143 /* Make rotation matrix */
146 z[0] = eyex - centerx;
147 z[1] = eyey - centery;
148 z[2] = eyez - centerz;
149 mag = sqrt( z[0]*z[0] + z[1]*z[1] + z[2]*z[2] );
150 if (mag) { /* mpichler, 19950515 */
161 /* X vector = Y cross Z */
162 x[0] = y[1]*z[2] - y[2]*z[1];
163 x[1] = -y[0]*z[2] + y[2]*z[0];
164 x[2] = y[0]*z[1] - y[1]*z[0];
166 /* Recompute Y = Z cross X */
167 y[0] = z[1]*x[2] - z[2]*x[1];
168 y[1] = -z[0]*x[2] + z[2]*x[0];
169 y[2] = z[0]*x[1] - z[1]*x[0];
171 /* mpichler, 19950515 */
172 /* cross product gives area of parallelogram, which is < 1.0 for
173 * non-perpendicular unit-length vectors; so normalize x, y here
176 mag = sqrt( x[0]*x[0] + x[1]*x[1] + x[2]*x[2] );
183 mag = sqrt( y[0]*y[0] + y[1]*y[1] + y[2]*y[2] );
190 #define M(row,col) m[col*4+row]
191 M(0,0) = x[0]; M(0,1) = x[1]; M(0,2) = x[2]; M(0,3) = 0.0;
192 M(1,0) = y[0]; M(1,1) = y[1]; M(1,2) = y[2]; M(1,3) = 0.0;
193 M(2,0) = z[0]; M(2,1) = z[1]; M(2,2) = z[2]; M(2,3) = 0.0;
194 // the following is part of the original gluLookAt(), but we are
195 // commenting it out because we know we are going to be doing a
196 // translation below which will set these values anyways
197 // M(3,0) = 0.0; M(3,1) = 0.0; M(3,2) = 0.0; M(3,3) = 1.0;
200 // Translate Eye to Origin
201 // replaces: glTranslated( -eyex, -eyey, -eyez );
203 // this has been slightly modified from the original glTranslate()
204 // code because we know that coming into this m[12] = m[13] =
205 // m[14] = 0.0, and m[15] = 1.0;
206 m[12] = m[0] * -eyex + m[4] * -eyey + m[8] * -eyez /* + m[12] */;
207 m[13] = m[1] * -eyex + m[5] * -eyey + m[9] * -eyez /* + m[13] */;
208 m[14] = m[2] * -eyex + m[6] * -eyey + m[10] * -eyez /* + m[14] */;
209 m[15] = 1.0 /* m[3] * -eyex + m[7] * -eyey + m[11] * -eyez + m[15] */;
211 // xglMultMatrixd( m );
216 // Update the view volume, position, and orientation
217 void FGView::UpdateViewParams( void ) {
218 FGInterface *f = current_aircraft.fdm_state;
223 if ((current_options.get_panel_status() != panel_hist) && (current_options.get_panel_status()))
225 FGPanel::OurPanel->ReInit( 0, 0, 1024, 768);
228 if ( ! current_options.get_panel_status() ) {
229 xglViewport(0, 0 , (GLint)(winWidth), (GLint)(winHeight) );
231 xglViewport(0, (GLint)((winHeight)*0.5768), (GLint)(winWidth),
232 (GLint)((winHeight)*0.4232) );
235 // Tell GL we are about to modify the projection parameters
236 xglMatrixMode(GL_PROJECTION);
238 if ( f->get_Altitude() * FEET_TO_METER - scenery.cur_elev > 10.0 ) {
239 gluPerspective(current_options.get_fov(), win_ratio, 10.0, 100000.0);
241 gluPerspective(current_options.get_fov(), win_ratio, 0.5, 100000.0);
242 // printf("Near ground, minimizing near clip plane\n");
246 xglMatrixMode(GL_MODELVIEW);
249 // set up our view volume (default)
250 #if !defined(FG_VIEW_INLINE_OPTIMIZATIONS)
251 LookAt(view_pos.x(), view_pos.y(), view_pos.z(),
252 view_pos.x() + view_forward[0],
253 view_pos.y() + view_forward[1],
254 view_pos.z() + view_forward[2],
255 view_up[0], view_up[1], view_up[2]);
257 // look almost straight up (testing and eclipse watching)
258 /* LookAt(view_pos.x(), view_pos.y(), view_pos.z(),
259 view_pos.x() + view_up[0] + .001,
260 view_pos.y() + view_up[1] + .001,
261 view_pos.z() + view_up[2] + .001,
262 view_up[0], view_up[1], view_up[2]); */
264 // lock view horizontally towards sun (testing)
265 /* LookAt(view_pos.x(), view_pos.y(), view_pos.z(),
266 view_pos.x() + surface_to_sun[0],
267 view_pos.y() + surface_to_sun[1],
268 view_pos.z() + surface_to_sun[2],
269 view_up[0], view_up[1], view_up[2]); */
271 // lock view horizontally towards south (testing)
272 /* LookAt(view_pos.x(), view_pos.y(), view_pos.z(),
273 view_pos.x() + surface_south[0],
274 view_pos.y() + surface_south[1],
275 view_pos.z() + surface_south[2],
276 view_up[0], view_up[1], view_up[2]); */
278 #else // defined(FG_VIEW_INLINE_OPTIMIZATIONS)
279 //void FGView::LookAt( GLdouble eyex, GLdouble eyey, GLdouble eyez,
280 // GLdouble centerx, GLdouble centery, GLdouble centerz,
281 // GLdouble upx, GLdouble upy, GLdouble upz )
284 GLdouble x[3], y[3], z[3];
287 m = current_view.MODEL_VIEW;
289 /* Make rotation matrix */
292 z[0] = -view_forward[0]; //eyex - centerx;
293 z[1] = -view_forward[1]; //eyey - centery;
294 z[2] = -view_forward[2]; //eyez - centerz;
296 // In our case this is a unit vector NHV
298 // mag = sqrt( z[0]*z[0] + z[1]*z[1] + z[2]*z[2] );
299 // if (mag) { /* mpichler, 19950515 */
301 // printf("mag(%f) ", mag);
308 y[0] = view_up[0]; //upx;
309 y[1] = view_up[1]; //upy;
310 y[2] = view_up[2]; //upz;
312 /* X vector = Y cross Z */
313 x[0] = y[1]*z[2] - y[2]*z[1];
314 x[1] = -y[0]*z[2] + y[2]*z[0];
315 x[2] = y[0]*z[1] - y[1]*z[0];
317 // printf(" %f %f %f ", y[0], y[1], y[2]);
319 /* Recompute Y = Z cross X */
320 // y[0] = z[1]*x[2] - z[2]*x[1];
321 // y[1] = -z[0]*x[2] + z[2]*x[0];
322 // y[2] = z[0]*x[1] - z[1]*x[0];
324 // printf(" %f %f %f\n", y[0], y[1], y[2]);
326 // In our case these are unit vectors NHV
328 /* mpichler, 19950515 */
329 /* cross product gives area of parallelogram, which is < 1.0 for
330 * non-perpendicular unit-length vectors; so normalize x, y here
333 // mag = sqrt( x[0]*x[0] + x[1]*x[1] + x[2]*x[2] );
336 // printf("mag2(%f) ", mag);
342 // mag = sqrt( y[0]*y[0] + y[1]*y[1] + y[2]*y[2] );
345 // printf("mag3(%f)\n", mag);
351 #define M(row,col) m[col*4+row]
352 M(0,0) = x[0]; M(0,1) = x[1]; M(0,2) = x[2]; M(0,3) = 0.0;
353 M(1,0) = y[0]; M(1,1) = y[1]; M(1,2) = y[2]; M(1,3) = 0.0;
354 M(2,0) = z[0]; M(2,1) = z[1]; M(2,2) = z[2]; M(2,3) = 0.0;
355 // the following is part of the original gluLookAt(), but we are
356 // commenting it out because we know we are going to be doing a
357 // translation below which will set these values anyways
358 // M(3,0) = 0.0; M(3,1) = 0.0; M(3,2) = 0.0; M(3,3) = 1.0;
361 // Translate Eye to Origin
362 // replaces: glTranslated( -eyex, -eyey, -eyez );
364 // this has been slightly modified from the original glTranslate()
365 // code because we know that coming into this m[12] = m[13] =
366 // m[14] = 0.0, and m[15] = 1.0;
367 m[12] = m[0] * -view_pos.x() + m[4] * -view_pos.y() + m[8] * -view_pos.z() /* + m[12] */;
368 m[13] = m[1] * -view_pos.x() + m[5] * -view_pos.y() + m[9] * -view_pos.z() /* + m[13] */;
369 m[14] = m[2] * -view_pos.x() + m[6] * -view_pos.y() + m[10] * -view_pos.z() /* + m[14] */;
370 m[15] = 1.0 /* m[3] * -view_pos.x() + m[7] * -view_pos.y() + m[11] * -view_pos.z() + m[15] */;
372 // xglMultMatrixd( m );
375 #endif // FG_VIEW_INLINE_OPTIMIZATIONS
378 panel_hist = current_options.get_panel_status();
382 void getRotMatrix(double* out, MAT3vec vec, double radians)
384 /* This function contributed by Erich Boleyn (erich@uruk.org) */
385 /* This function used from the Mesa OpenGL code (matrix.c) */
387 double vx, vy, vz, xy, yz, zx, xs, ys, zs, one_c; //, xx, yy, zz
393 // mag = getMagnitude();
399 #define M(row,col) out[row*4 + col]
402 * Arbitrary axis rotation matrix.
404 * This is composed of 5 matrices, Rz, Ry, T, Ry', Rz', multiplied
405 * like so: Rz * Ry * T * Ry' * Rz'. T is the final rotation
406 * (which is about the X-axis), and the two composite transforms
407 * Ry' * Rz' and Rz * Ry are (respectively) the rotations necessary
408 * from the arbitrary axis to the X-axis then back. They are
409 * all elementary rotations.
411 * Rz' is a rotation about the Z-axis, to bring the axis vector
412 * into the x-z plane. Then Ry' is applied, rotating about the
413 * Y-axis to bring the axis vector parallel with the X-axis. The
414 * rotation about the X-axis is then performed. Ry and Rz are
415 * simply the respective inverse transforms to bring the arbitrary
416 * axis back to it's original orientation. The first transforms
417 * Rz' and Ry' are considered inverses, since the data from the
418 * arbitrary axis gives you info on how to get to it, not how
419 * to get away from it, and an inverse must be applied.
421 * The basic calculation used is to recognize that the arbitrary
422 * axis vector (x, y, z), since it is of unit length, actually
423 * represents the sines and cosines of the angles to rotate the
424 * X-axis to the same orientation, with theta being the angle about
425 * Z and phi the angle about Y (in the order described above)
428 * cos ( theta ) = x / sqrt ( 1 - z^2 )
429 * sin ( theta ) = y / sqrt ( 1 - z^2 )
431 * cos ( phi ) = sqrt ( 1 - z^2 )
434 * Note that cos ( phi ) can further be inserted to the above
437 * cos ( theta ) = x / cos ( phi )
438 * sin ( theta ) = y / cos ( phi )
440 * ...etc. Because of those relations and the standard trigonometric
441 * relations, it is pssible to reduce the transforms down to what
442 * is used below. It may be that any primary axis chosen will give the
443 * same results (modulo a sign convention) using thie method.
445 * Particularly nice is to notice that all divisions that might
446 * have caused trouble when parallel to certain planes or
447 * axis go away with care paid to reducing the expressions.
448 * After checking, it does perform correctly under all cases, since
449 * in all the cases of division where the denominator would have
450 * been zero, the numerator would have been zero as well, giving
451 * the expected result.
465 M(0,0) = (one_c * vx * vx) + c;
467 yz = vy * vz * one_c;
471 M(1,1) = (one_c * vy * vy) + c;
473 zx = vz * vx * one_c;
477 M(2,2) = (one_c * vz *vz) + c;
479 xy = vx * vy * one_c;
483 // M(0,0) = (one_c * xx) + c;
484 // M(1,0) = (one_c * xy) - zs;
485 // M(2,0) = (one_c * zx) + ys;
487 // M(0,1) = (one_c * xy) + zs;
488 // M(1,1) = (one_c * yy) + c;
489 // M(2,1) = (one_c * yz) - xs;
491 // M(0,2) = (one_c * zx) - ys;
492 // M(1,2) = (one_c * yz) + xs;
493 // M(2,2) = (one_c * zz) + c;
499 // Update the view parameters
500 void FGView::UpdateViewMath( FGInterface *f ) {
502 MAT3vec vec, forward, v0, minus_z;
503 MAT3mat R, TMP, UP, LOCAL, VIEW;
507 // printf("Updating fov\n");
508 UpdateFOV( current_options );
512 scenery.center = scenery.next_center;
514 #if !defined(FG_VIEW_INLINE_OPTIMIZATIONS)
515 // printf("scenery center = %.2f %.2f %.2f\n", scenery.center.x,
516 // scenery.center.y, scenery.center.z);
518 // calculate the cartesion coords of the current lat/lon/0 elev
519 p = Point3D( f->get_Longitude(),
520 f->get_Lat_geocentric(),
521 f->get_Sea_level_radius() * FEET_TO_METER );
523 cur_zero_elev = fgPolarToCart3d(p) - scenery.center;
525 // calculate view position in current FG view coordinate system
526 // p.lon & p.lat are already defined earlier, p.radius was set to
527 // the sea level radius, so now we add in our altitude.
528 if ( f->get_Altitude() * FEET_TO_METER >
529 (scenery.cur_elev + 0.5 * METER_TO_FEET) ) {
530 p.setz( p.radius() + f->get_Altitude() * FEET_TO_METER );
532 p.setz( p.radius() + scenery.cur_elev + 0.5 * METER_TO_FEET );
535 abs_view_pos = fgPolarToCart3d(p);
537 #else // FG_VIEW_INLINE_OPTIMIZATIONS
539 double tmp_radius = f->get_Sea_level_radius() * FEET_TO_METER;
540 double tmp = f->get_cos_lat_geocentric() * tmp_radius;
542 cur_zero_elev.setx(f->get_cos_longitude()*tmp - scenery.center.x());
543 cur_zero_elev.sety(f->get_sin_longitude()*tmp - scenery.center.y());
544 cur_zero_elev.setz(f->get_sin_lat_geocentric()*tmp_radius - scenery.center.z());
546 // calculate view position in current FG view coordinate system
547 // p.lon & p.lat are already defined earlier, p.radius was set to
548 // the sea level radius, so now we add in our altitude.
549 if ( f->get_Altitude() * FEET_TO_METER >
550 (scenery.cur_elev + 0.5 * METER_TO_FEET) ) {
551 tmp_radius += f->get_Altitude() * FEET_TO_METER;
553 tmp_radius += scenery.cur_elev + 0.5 * METER_TO_FEET ;
555 tmp = f->get_cos_lat_geocentric() * tmp_radius;
556 abs_view_pos.setx(f->get_cos_longitude()*tmp);
557 abs_view_pos.sety(f->get_sin_longitude()*tmp);
558 abs_view_pos.setz(f->get_sin_lat_geocentric()*tmp_radius);
560 #endif // FG_VIEW_INLINE_OPTIMIZATIONS
562 view_pos = abs_view_pos - scenery.center;
564 FG_LOG( FG_VIEW, FG_DEBUG, "Polar view pos = " << p );
565 FG_LOG( FG_VIEW, FG_DEBUG, "Absolute view pos = " << abs_view_pos );
566 FG_LOG( FG_VIEW, FG_DEBUG, "Relative view pos = " << view_pos );
568 // Derive the LOCAL aircraft rotation matrix (roll, pitch, yaw)
569 // from FG_T_local_to_body[3][3]
571 if ( use_larcsim_local_to_body ) {
573 // Question: Why is the LaRCsim matrix arranged so differently
574 // than the one we need???
576 // Answer (I think): The LaRCsim matrix is generated in a
577 // different reference frame than we've set up for our world
579 LOCAL[0][0] = f->get_T_local_to_body_33();
580 LOCAL[0][1] = -f->get_T_local_to_body_32();
581 LOCAL[0][2] = -f->get_T_local_to_body_31();
583 LOCAL[1][0] = -f->get_T_local_to_body_23();
584 LOCAL[1][1] = f->get_T_local_to_body_22();
585 LOCAL[1][2] = f->get_T_local_to_body_21();
587 LOCAL[2][0] = -f->get_T_local_to_body_13();
588 LOCAL[2][1] = f->get_T_local_to_body_12();
589 LOCAL[2][2] = f->get_T_local_to_body_11();
591 LOCAL[3][0] = LOCAL[3][1] = LOCAL[3][2] = LOCAL[3][3] = 0.0;
594 // printf("LaRCsim LOCAL matrix\n");
595 // MAT3print(LOCAL, stdout);
599 // code to calculate LOCAL matrix calculated from Phi, Theta, and
600 // Psi (roll, pitch, yaw) in case we aren't running LaRCsim as our
603 MAT3_SET_VEC(vec, 0.0, 0.0, 1.0);
604 MAT3rotate(R, vec, f->get_Phi());
605 /* printf("Roll matrix\n"); */
606 /* MAT3print(R, stdout); */
608 MAT3_SET_VEC(vec, 0.0, 1.0, 0.0);
609 /* MAT3mult_vec(vec, vec, R); */
610 MAT3rotate(TMP, vec, f->get_Theta());
611 /* printf("Pitch matrix\n"); */
612 /* MAT3print(TMP, stdout); */
615 MAT3_SET_VEC(vec, 1.0, 0.0, 0.0);
616 /* MAT3mult_vec(vec, vec, R); */
617 /* MAT3rotate(TMP, vec, FG_Psi - FG_PI_2); */
618 MAT3rotate(TMP, vec, -f->get_Psi());
619 /* printf("Yaw matrix\n");
620 MAT3print(TMP, stdout); */
621 MAT3mult(LOCAL, R, TMP);
622 // printf("FG derived LOCAL matrix\n");
623 // MAT3print(LOCAL, stdout);
625 } // if ( use_larcsim_local_to_body )
627 #if !defined(FG_VIEW_INLINE_OPTIMIZATIONS)
629 // Derive the local UP transformation matrix based on *geodetic*
631 MAT3_SET_VEC(vec, 0.0, 0.0, 1.0);
632 MAT3rotate(R, vec, f->get_Longitude()); // R = rotate about Z axis
633 // printf("Longitude matrix\n");
634 // MAT3print(R, stdout);
636 MAT3_SET_VEC(vec, 0.0, 1.0, 0.0);
637 MAT3mult_vec(vec, vec, R);
638 MAT3rotate(TMP, vec, -f->get_Latitude()); // TMP = rotate about X axis
639 // printf("Latitude matrix\n");
640 // MAT3print(TMP, stdout);
642 MAT3mult(UP, R, TMP);
643 // printf("Local up matrix\n");
644 // MAT3print(UP, stdout);
646 MAT3_SET_VEC(local_up, 1.0, 0.0, 0.0);
647 MAT3mult_vec(local_up, local_up, UP);
649 // printf( "Local Up = (%.4f, %.4f, %.4f)\n",
650 // local_up[0], local_up[1], local_up[2]);
652 // Alternative method to Derive local up vector based on
653 // *geodetic* coordinates
654 // alt_up = fgPolarToCart(FG_Longitude, FG_Latitude, 1.0);
655 // printf( " Alt Up = (%.4f, %.4f, %.4f)\n",
656 // alt_up.x, alt_up.y, alt_up.z);
658 // Calculate the VIEW matrix
659 MAT3mult(VIEW, LOCAL, UP);
660 // printf("VIEW matrix\n");
661 // MAT3print(VIEW, stdout);
663 // generate the current up, forward, and fwrd-view vectors
664 MAT3_SET_VEC(vec, 1.0, 0.0, 0.0);
665 MAT3mult_vec(view_up, vec, VIEW);
667 MAT3_SET_VEC(vec, 0.0, 0.0, 1.0);
668 MAT3mult_vec(forward, vec, VIEW);
669 // printf( "Forward vector is (%.2f,%.2f,%.2f)\n", forward[0], forward[1],
672 MAT3rotate(TMP, view_up, view_offset);
673 MAT3mult_vec(view_forward, forward, TMP);
675 // make a vector to the current view position
676 MAT3_SET_VEC(v0, view_pos.x(), view_pos.y(), view_pos.z());
678 // Given a vector pointing straight down (-Z), map into onto the
679 // local plane representing "horizontal". This should give us the
680 // local direction for moving "south".
681 MAT3_SET_VEC(minus_z, 0.0, 0.0, -1.0);
682 map_vec_onto_cur_surface_plane(local_up, v0, minus_z, surface_south);
683 MAT3_NORMALIZE_VEC(surface_south, ntmp);
684 // printf( "Surface direction directly south %.2f %.2f %.2f\n",
685 // surface_south[0], surface_south[1], surface_south[2]);
687 // now calculate the surface east vector
688 MAT3rotate(TMP, view_up, FG_PI_2);
689 MAT3mult_vec(surface_east, surface_south, TMP);
690 // printf( "Surface direction directly east %.2f %.2f %.2f\n",
691 // surface_east[0], surface_east[1], surface_east[2]);
692 // printf( "Should be close to zero = %.2f\n",
693 // MAT3_DOT_PRODUCT(surface_south, surface_east));
695 #else // FG_VIEW_INLINE_OPTIMIZATIONS
697 // // Build spherical to cartesian transform matrix directly
698 double cos_lat = f->get_cos_latitude(); // cos(-f->get_Latitude());
699 double sin_lat = -f->get_sin_latitude(); // sin(-f->get_Latitude());
700 double cos_lon = f->get_cos_longitude(); //cos(f->get_Longitude());
701 double sin_lon = f->get_sin_longitude(); //sin(f->get_Longitude());
703 double *mat = (double *)UP;
705 mat[0] = cos_lat*cos_lon;
706 mat[1] = cos_lat*sin_lon;
713 mat[8] = sin_lat*cos_lon;
714 mat[9] = sin_lat*sin_lon;
716 mat[11] = mat[12] = mat[13] = mat[14] = 0.0;
719 MAT3mult(VIEW, LOCAL, UP);
721 // THESE COULD JUST BE POINTERS !!!
722 MAT3_SET_VEC(local_up, mat[0], mat[1], mat[2]);
723 MAT3_SET_VEC(view_up, VIEW[0][0], VIEW[0][1], VIEW[0][2]);
724 MAT3_SET_VEC(forward, VIEW[2][0], VIEW[2][1], VIEW[2][2]);
726 getRotMatrix((double *)TMP, view_up, view_offset);
727 MAT3mult_vec(view_forward, forward, TMP);
729 // make a vector to the current view position
730 MAT3_SET_VEC(v0, view_pos.x(), view_pos.y(), view_pos.z());
732 // Given a vector pointing straight down (-Z), map into onto the
733 // local plane representing "horizontal". This should give us the
734 // local direction for moving "south".
735 MAT3_SET_VEC(minus_z, 0.0, 0.0, -1.0);
736 map_vec_onto_cur_surface_plane(local_up, v0, minus_z, surface_south);
738 MAT3_NORMALIZE_VEC(surface_south, ntmp);
739 // printf( "Surface direction directly south %.6f %.6f %.6f\n",
740 // surface_south[0], surface_south[1], surface_south[2]);
742 // now calculate the surface east vector
743 getRotMatrix((double *)TMP, view_up, FG_PI_2);
744 MAT3mult_vec(surface_east, surface_south, TMP);
745 // printf( "Surface direction directly east %.6f %.6f %.6f\n",
746 // surface_east[0], surface_east[1], surface_east[2]);
747 // printf( "Should be close to zero = %.6f\n",
748 // MAT3_DOT_PRODUCT(surface_south, surface_east));
749 #endif // !defined(FG_VIEW_INLINE_OPTIMIZATIONS)
753 // Update the "World to Eye" transformation matrix
754 // This is most useful for view frustum culling
755 void FGView::UpdateWorldToEye( FGInterface *f ) {
756 MAT3mat R_Phi, R_Theta, R_Psi, R_Lat, R_Lon, T_view;
760 if ( use_larcsim_local_to_body ) {
762 // Question: hey this is even different then LOCAL[][] above??
763 // Answer: yet another coordinate system, this time the
764 // coordinate system in which we do our view frustum culling.
766 AIRCRAFT[0][0] = -f->get_T_local_to_body_22();
767 AIRCRAFT[0][1] = -f->get_T_local_to_body_23();
768 AIRCRAFT[0][2] = f->get_T_local_to_body_21();
769 AIRCRAFT[0][3] = 0.0;
770 AIRCRAFT[1][0] = f->get_T_local_to_body_32();
771 AIRCRAFT[1][1] = f->get_T_local_to_body_33();
772 AIRCRAFT[1][2] = -f->get_T_local_to_body_31();
773 AIRCRAFT[1][3] = 0.0;
774 AIRCRAFT[2][0] = f->get_T_local_to_body_12();
775 AIRCRAFT[2][1] = f->get_T_local_to_body_13();
776 AIRCRAFT[2][2] = -f->get_T_local_to_body_11();
777 AIRCRAFT[2][3] = 0.0;
778 AIRCRAFT[3][0] = AIRCRAFT[3][1] = AIRCRAFT[3][2] = AIRCRAFT[3][3] = 0.0;
779 AIRCRAFT[3][3] = 1.0;
784 MAT3_SET_HVEC(vec, 0.0, 0.0, -1.0, 1.0);
785 MAT3rotate(R_Phi, vec, f->get_Phi());
786 // printf("Roll matrix (Phi)\n");
787 // MAT3print(R_Phi, stdout);
790 MAT3_SET_HVEC(vec, 1.0, 0.0, 0.0, 1.0);
791 MAT3rotate(R_Theta, vec, f->get_Theta());
792 // printf("\nPitch matrix (Theta)\n");
793 // MAT3print(R_Theta, stdout);
796 MAT3_SET_HVEC(vec, 0.0, -1.0, 0.0, 1.0);
797 MAT3rotate(R_Psi, vec, f->get_Psi() + FG_PI /* - view_offset */ );
798 // MAT3rotate(R_Psi, vec, f->get_Psi() + FG_PI - view_offset );
799 // printf("\nYaw matrix (Psi)\n");
800 // MAT3print(R_Psi, stdout);
802 // aircraft roll/pitch/yaw
803 MAT3mult(TMP, R_Phi, R_Theta);
804 MAT3mult(AIRCRAFT, TMP, R_Psi);
806 } // if ( use_larcsim_local_to_body )
808 #if !defined(FG_VIEW_INLINE_OPTIMIZATIONS)
810 // printf("AIRCRAFT matrix\n");
811 // MAT3print(AIRCRAFT, stdout);
813 // View rotation matrix relative to current aircraft orientation
814 MAT3_SET_HVEC(vec, 0.0, -1.0, 0.0, 1.0);
815 MAT3mult_vec(vec, vec, AIRCRAFT);
816 // printf("aircraft up vector = %.2f %.2f %.2f\n",
817 // vec[0], vec[1], vec[2]);
818 MAT3rotate(TMP, vec, -view_offset );
819 MAT3mult(VIEW_OFFSET, AIRCRAFT, TMP);
820 // printf("VIEW_OFFSET matrix\n");
821 // MAT3print(VIEW_OFFSET, stdout);
823 // View position in scenery centered coordinates
824 MAT3_SET_HVEC(vec, view_pos.x(), view_pos.y(), view_pos.z(), 1.0);
825 MAT3translate(T_view, vec);
826 // printf("\nTranslation matrix\n");
827 // MAT3print(T_view, stdout);
830 MAT3_SET_HVEC(vec, 1.0, 0.0, 0.0, 1.0);
831 // R_Lat = rotate about X axis
832 MAT3rotate(R_Lat, vec, f->get_Latitude());
833 // printf("\nLatitude matrix\n");
834 // MAT3print(R_Lat, stdout);
837 MAT3_SET_HVEC(vec, 0.0, 0.0, 1.0, 1.0);
838 // R_Lon = rotate about Z axis
839 MAT3rotate(R_Lon, vec, f->get_Longitude() - FG_PI_2 );
840 // printf("\nLongitude matrix\n");
841 // MAT3print(R_Lon, stdout);
844 MAT3mult(WORLD, R_Lat, R_Lon);
845 // printf("\nworld\n");
846 // MAT3print(WORLD, stdout);
848 MAT3mult(EYE_TO_WORLD, VIEW_OFFSET, WORLD);
849 MAT3mult(EYE_TO_WORLD, EYE_TO_WORLD, T_view);
850 // printf("\nEye to world\n");
851 // MAT3print(EYE_TO_WORLD, stdout);
853 MAT3invert(WORLD_TO_EYE, EYE_TO_WORLD);
854 // printf("\nWorld to eye\n");
855 // MAT3print(WORLD_TO_EYE, stdout);
857 // printf( "\nview_pos = %.2f %.2f %.2f\n",
858 // view_pos.x, view_pos.y, view_pos.z );
860 // MAT3_SET_HVEC(eye, 0.0, 0.0, 0.0, 1.0);
861 // MAT3mult_vec(vec, eye, EYE_TO_WORLD);
862 // printf("\neye -> world = %.2f %.2f %.2f\n", vec[0], vec[1], vec[2]);
864 // MAT3_SET_HVEC(vec1, view_pos.x, view_pos.y, view_pos.z, 1.0);
865 // MAT3mult_vec(vec, vec1, WORLD_TO_EYE);
866 // printf( "\nabs_view_pos -> eye = %.2f %.2f %.2f\n",
867 // vec[0], vec[1], vec[2]);
868 #else // FG_VIEW_INLINE_OPTIMIZATIONS
870 MAT3_SET_HVEC(vec, -AIRCRAFT[1][0], -AIRCRAFT[1][1], -AIRCRAFT[1][2], -AIRCRAFT[1][3]);
871 getRotMatrix((double *)TMP, vec, -view_offset );
872 MAT3mult(VIEW_OFFSET, AIRCRAFT, TMP);
873 // MAT3print_formatted(VIEW_OFFSET, stdout, "VIEW_OFFSET matrix:\n",
874 // NULL, "%#8.6f ", "\n");
876 // Build spherical to cartesian transform matrix directly
877 double *mat = (double *)WORLD; //T_view; //WORLD;
878 double cos_lat = f->get_cos_latitude(); //cos(f->get_Latitude());
879 double sin_lat = f->get_sin_latitude(); //sin(f->get_Latitude());
880 // using trig identities this:
881 // mat[0] = cos(f->get_Longitude() - FG_PI_2);//cos_lon;
882 // mat[1] = sin(f->get_Longitude() - FG_PI_2);//sin_lon;
884 mat[0] = f->get_sin_longitude(); //cos_lon;
885 mat[1] = -f->get_cos_longitude(); //sin_lon;
886 mat[4] = -cos_lat*mat[1]; //mat[1]=sin_lon;
887 mat[5] = cos_lat*mat[0]; //mat[0]=cos_lon;
889 mat[8] = sin_lat*mat[1]; //mat[1]=sin_lon;
890 mat[9] = -sin_lat*mat[0]; //mat[0]=cos_lon;
893 // BUILD EYE_TO_WORLD = AIRCRAFT * WORLD
894 // and WORLD_TO_EYE = Inverse( EYE_TO_WORLD) concurrently
895 // by Transposing the 3x3 rotation sub-matrix
896 WORLD_TO_EYE[0][0] = EYE_TO_WORLD[0][0] =
897 VIEW_OFFSET[0][0]*mat[0] + VIEW_OFFSET[0][1]*mat[4] + VIEW_OFFSET[0][2]*mat[8];
899 WORLD_TO_EYE[1][0] = EYE_TO_WORLD[0][1] =
900 VIEW_OFFSET[0][0]*mat[1] + VIEW_OFFSET[0][1]*mat[5] + VIEW_OFFSET[0][2]*mat[9];
902 WORLD_TO_EYE[2][0] = EYE_TO_WORLD[0][2] =
903 VIEW_OFFSET[0][1]*mat[6] + VIEW_OFFSET[0][2]*mat[10];
905 WORLD_TO_EYE[0][1] = EYE_TO_WORLD[1][0] =
906 VIEW_OFFSET[1][0]*mat[0] + VIEW_OFFSET[1][1]*mat[4] + VIEW_OFFSET[1][2]*mat[8];
908 WORLD_TO_EYE[1][1] = EYE_TO_WORLD[1][1] =
909 VIEW_OFFSET[1][0]*mat[1] + VIEW_OFFSET[1][1]*mat[5] + VIEW_OFFSET[1][2]*mat[9];
911 WORLD_TO_EYE[2][1] = EYE_TO_WORLD[1][2] =
912 VIEW_OFFSET[1][1]*mat[6] + VIEW_OFFSET[1][2]*mat[10];
914 WORLD_TO_EYE[0][2] = EYE_TO_WORLD[2][0] =
915 VIEW_OFFSET[2][0]*mat[0] + VIEW_OFFSET[2][1]*mat[4] + VIEW_OFFSET[2][2]*mat[8];
917 WORLD_TO_EYE[1][2] = EYE_TO_WORLD[2][1] =
918 VIEW_OFFSET[2][0]*mat[1] + VIEW_OFFSET[2][1]*mat[5] + VIEW_OFFSET[2][2]*mat[9];
920 WORLD_TO_EYE[2][2] = EYE_TO_WORLD[2][2] =
921 VIEW_OFFSET[2][1]*mat[6] + VIEW_OFFSET[2][2]*mat[10];
923 // TRANSLATE TO VIEW POSITION
924 EYE_TO_WORLD[3][0] = view_pos.x();
925 EYE_TO_WORLD[3][1] = view_pos.y();
926 EYE_TO_WORLD[3][2] = view_pos.z();
929 WORLD_TO_EYE[0][3] = WORLD_TO_EYE[1][3] = WORLD_TO_EYE[2][3] =
930 EYE_TO_WORLD[0][3] = EYE_TO_WORLD[1][3] = EYE_TO_WORLD[2][3] = 0.0;
932 // FILL UNITY ENTRIES
933 WORLD_TO_EYE[3][3] = EYE_TO_WORLD[3][3] = 1.0;
935 /* MAKE THE INVERTED TRANSLATIONS */
936 mat = (double *)EYE_TO_WORLD;
937 WORLD_TO_EYE[3][0] = -mat[12]*mat[0]
941 WORLD_TO_EYE[3][1] = -mat[12]*mat[4]
945 WORLD_TO_EYE[3][2] = -mat[12]*mat[8]
949 // MAT3print_formatted(EYE_TO_WORLD, stdout, "EYE_TO_WORLD matrix:\n",
950 // NULL, "%#8.6f ", "\n");
952 // MAT3print_formatted(WORLD_TO_EYE, stdout, "WORLD_TO_EYE matrix:\n",
953 // NULL, "%#8.6f ", "\n");
955 #endif // defined(FG_VIEW_INLINE_OPTIMIZATIONS)
960 // Reject non viewable spheres from current View Frustrum by Curt
961 // Olson curt@me.umn.edu and Norman Vine nhv@yahoo.com with 'gentle
962 // guidance' from Steve Baker sbaker@link.com
964 FGView::SphereClip( const Point3D& cp, const double radius )
976 mat = (double *)(WORLD_TO_EYE);
978 eye[2] = x*mat[2] + y*mat[6] + z*mat[10] + mat[14];
980 // Check near and far clip plane
981 if( ( eye[2] > radius ) ||
982 ( eye[2] + radius + current_weather.visibility < 0) )
983 // ( eye[2] + radius + far_plane < 0) )
988 // check right and left clip plane (from eye perspective)
989 x1 = radius * fov_x_clip;
990 eye[0] = (x*mat[0] + y*mat[4] + z*mat[8] + mat[12]) * slope_x;
991 if( (eye[2] > -(eye[0]+x1)) || (eye[2] > (eye[0]-x1)) ) {
995 // check bottom and top clip plane (from eye perspective)
996 y1 = radius * fov_y_clip;
997 eye[1] = (x*mat[1] + y*mat[5] + z*mat[9] + mat[13]) * slope_y;
998 if( (eye[2] > -(eye[1]+y1)) || (eye[2] > (eye[1]-y1)) ) {
1008 FGView::~FGView( void ) {
1013 // Revision 1.35 1999/04/03 04:21:04 curt
1014 // Integration of Steve's plib conglomeration.
1015 // Optimizations (tm) by Norman Vine.
1017 // Revision 1.34 1999/03/08 21:56:41 curt
1018 // Added panel changes sent in by Friedemann.
1019 // Added a splash screen randomization since we have several nice splash screens.
1021 // Revision 1.33 1999/02/05 21:29:14 curt
1022 // Modifications to incorporate Jon S. Berndts flight model code.
1024 // Revision 1.32 1999/01/07 20:25:12 curt
1025 // Updated struct fgGENERAL to class FGGeneral.
1027 // Revision 1.31 1998/12/11 20:26:28 curt
1028 // Fixed view frustum culling accuracy bug so we can look out the sides and
1029 // back without tri-stripes dropping out.
1031 // Revision 1.30 1998/12/09 18:50:28 curt
1032 // Converted "class fgVIEW" to "class FGView" and updated to make data
1033 // members private and make required accessor functions.
1035 // Revision 1.29 1998/12/05 15:54:24 curt
1036 // Renamed class fgFLIGHT to class FGState as per request by JSB.
1038 // Revision 1.28 1998/12/03 01:17:20 curt
1039 // Converted fgFLIGHT to a class.
1041 // Revision 1.27 1998/11/16 14:00:06 curt
1042 // Added pow() macro bug work around.
1043 // Added support for starting FGFS at various resolutions.
1044 // Added some initial serial port support.
1045 // Specify default log levels in main().
1047 // Revision 1.26 1998/11/09 23:39:25 curt
1048 // Tweaks for the instrument panel.
1050 // Revision 1.25 1998/11/06 21:18:15 curt
1051 // Converted to new logstream debugging facility. This allows release
1052 // builds with no messages at all (and no performance impact) by using
1053 // the -DFG_NDEBUG flag.
1055 // Revision 1.24 1998/10/18 01:17:19 curt
1058 // Revision 1.23 1998/10/17 01:34:26 curt
1061 // Revision 1.22 1998/10/16 00:54:03 curt
1062 // Converted to Point3D class.
1064 // Revision 1.21 1998/09/17 18:35:33 curt
1065 // Added F8 to toggle fog and F9 to toggle texturing.
1067 // Revision 1.20 1998/09/08 15:04:35 curt
1068 // Optimizations by Norman Vine.
1070 // Revision 1.19 1998/08/20 20:32:34 curt
1071 // Reshuffled some of the code in and around views.[ch]xx
1073 // Revision 1.18 1998/07/24 21:57:02 curt
1074 // Set near clip plane to 0.5 meters when close to the ground. Also, let the view get a bit closer to the ground before hitting the hard limit.
1076 // Revision 1.17 1998/07/24 21:39:12 curt
1077 // Debugging output tweaks.
1078 // Cast glGetString to (char *) to avoid compiler errors.
1079 // Optimizations to fgGluLookAt() by Norman Vine.
1081 // Revision 1.16 1998/07/13 21:01:41 curt
1082 // Wrote access functions for current fgOPTIONS.
1084 // Revision 1.15 1998/07/12 03:14:43 curt
1085 // Added ground collision detection.
1086 // Did some serious horsing around to be able to "hug" the ground properly
1087 // and still be able to take off.
1088 // Set the near clip plane to 1.0 meters when less than 10 meters above the
1090 // Did some serious horsing around getting the initial airplane position to be
1091 // correct based on rendered terrain elevation.
1092 // Added a little cheat/hack that will prevent the view position from ever
1093 // dropping below the terrain, even when the flight model doesn't quite
1094 // put you as high as you'd like.
1096 // Revision 1.14 1998/07/08 14:45:08 curt
1097 // polar3d.h renamed to polar3d.hxx
1098 // vector.h renamed to vector.hxx
1099 // updated audio support so it waits to create audio classes (and tie up
1100 // /dev/dsp) until the mpg123 player is finished.
1102 // Revision 1.13 1998/07/04 00:52:27 curt
1103 // Add my own version of gluLookAt() (which is nearly identical to the
1104 // Mesa/glu version.) But, by calculating the Model View matrix our selves
1105 // we can save this matrix without having to read it back in from the video
1106 // card. This hopefully allows us to save a few cpu cycles when rendering
1107 // out the fragments because we can just use glLoadMatrixd() with the
1108 // precalculated matrix for each tile rather than doing a push(), translate(),
1109 // pop() for every fragment.
1111 // Panel status defaults to off for now until it gets a bit more developed.
1113 // Extract OpenGL driver info on initialization.
1115 // Revision 1.12 1998/06/03 00:47:15 curt
1116 // Updated to compile in audio support if OSS available.
1117 // Updated for new version of Steve's audio library.
1118 // STL includes don't use .h
1119 // Small view optimizations.
1121 // Revision 1.11 1998/05/27 02:24:05 curt
1122 // View optimizations by Norman Vine.
1124 // Revision 1.10 1998/05/17 16:59:03 curt
1125 // First pass at view frustum culling now operational.
1127 // Revision 1.9 1998/05/16 13:08:37 curt
1128 // C++ - ified views.[ch]xx
1129 // Shuffled some additional view parameters into the fgVIEW class.
1130 // Changed tile-radius to tile-diameter because it is a much better
1132 // Added a WORLD_TO_EYE transformation to views.cxx. This allows us
1133 // to transform world space to eye space for view frustum culling.
1135 // Revision 1.8 1998/05/02 01:51:01 curt
1136 // Updated polartocart conversion routine.
1138 // Revision 1.7 1998/04/30 12:34:20 curt
1139 // Added command line rendering options:
1140 // enable/disable fog/haze
1141 // specify smooth/flat shading
1142 // disable sky blending and just use a solid color
1143 // enable wireframe drawing mode
1145 // Revision 1.6 1998/04/28 01:20:23 curt
1146 // Type-ified fgTIME and fgVIEW.
1147 // Added a command line option to disable textures.
1149 // Revision 1.5 1998/04/26 05:10:04 curt
1150 // "struct fgLIGHT" -> "fgLIGHT" because fgLIGHT is typedef'd.
1152 // Revision 1.4 1998/04/25 22:04:53 curt
1153 // Use already calculated LaRCsim values to create the roll/pitch/yaw
1154 // transformation matrix (we call it LOCAL)
1156 // Revision 1.3 1998/04/25 20:24:02 curt
1157 // Cleaned up initialization sequence to eliminate interdependencies
1158 // between sun position, lighting, and view position. This creates a
1159 // valid single pass initialization path.
1161 // Revision 1.2 1998/04/24 00:49:22 curt
1162 // Wrapped "#include <config.h>" in "#ifdef HAVE_CONFIG_H"
1163 // Trying out some different option parsing code.
1164 // Some code reorganization.
1166 // Revision 1.1 1998/04/22 13:25:45 curt
1167 // C++ - ifing the code.
1168 // Starting a bit of reorganization of lighting code.
1170 // Revision 1.16 1998/04/18 04:11:29 curt
1171 // Moved fg_debug to it's own library, added zlib support.
1173 // Revision 1.15 1998/02/20 00:16:24 curt
1174 // Thursday's tweaks.
1176 // Revision 1.14 1998/02/09 15:07:50 curt
1179 // Revision 1.13 1998/02/07 15:29:45 curt
1180 // Incorporated HUD changes and struct/typedef changes from Charlie Hotchkiss
1181 // <chotchkiss@namg.us.anritsu.com>
1183 // Revision 1.12 1998/01/29 00:50:28 curt
1184 // Added a view record field for absolute x, y, z position.
1186 // Revision 1.11 1998/01/27 00:47:58 curt
1187 // Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
1188 // system and commandline/config file processing code.
1190 // Revision 1.10 1998/01/19 19:27:09 curt
1191 // Merged in make system changes from Bob Kuehne <rpk@sgi.com>
1192 // This should simplify things tremendously.
1194 // Revision 1.9 1998/01/13 00:23:09 curt
1195 // Initial changes to support loading and management of scenery tiles. Note,
1196 // there's still a fair amount of work left to be done.
1198 // Revision 1.8 1997/12/30 22:22:33 curt
1199 // Further integration of event manager.
1201 // Revision 1.7 1997/12/30 20:47:45 curt
1202 // Integrated new event manager with subsystem initializations.
1204 // Revision 1.6 1997/12/22 04:14:32 curt
1205 // Aligned sky with sun so dusk/dawn effects can be correct relative to the sun.
1207 // Revision 1.5 1997/12/18 04:07:02 curt
1208 // Worked on properly translating and positioning the sky dome.
1210 // Revision 1.4 1997/12/17 23:13:36 curt
1211 // Began working on rendering a sky.
1213 // Revision 1.3 1997/12/15 23:54:50 curt
1214 // Add xgl wrappers for debugging.
1215 // Generate terrain normals on the fly.
1217 // Revision 1.2 1997/12/10 22:37:48 curt
1218 // Prepended "fg" on the name of all global structures that didn't have it yet.
1219 // i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
1221 // Revision 1.1 1997/08/27 21:31:17 curt
1222 // Initial revision.