1 // HUD_ladder.cxx -- HUD Ladder Instrument
3 // Written by Michele America, started September 1997.
5 // Copyright (C) 1997 Michele F. America [micheleamerica#geocities:com]
6 // Copyright (C) 2006 Melchior FRANZ [mfranz#aon:at]
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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
26 #include <Main/viewer.hxx>
31 float get__heading() { return fgGetFloat("/orientation/heading-deg") * M_PI / 180.0; }
32 float get__throttleval() { return fgGetFloat("/controls/engines/engine/throttle"); }
33 float get__aoa() { return fgGetFloat("/sim/frame-rate"); } // FIXME
34 float get__Vx() { return fgGetFloat("/velocities/uBody-fps"); }
35 float get__Vy() { return fgGetFloat("/velocities/vBody-fps"); }
36 float get__Vz() { return fgGetFloat("/velocities/wBody-fps"); }
37 float get__Ax() { return fgGetFloat("/acclerations/pilot/x-accel-fps_sec"); }
38 float get__Ay() { return fgGetFloat("/acclerations/pilot/y-accel-fps_sec"); }
39 float get__Az() { return fgGetFloat("/acclerations/pilot/z-accel-fps_sec"); }
43 HUD::Ladder::Ladder(HUD *hud, const SGPropertyNode *n, float x, float y) :
45 _pitch(n->getNode("pitch-input", false)),
46 _roll(n->getNode("roll-input", false)),
47 _width_units(int(n->getFloatValue("display-span"))),
48 _div_units(int(fabs(n->getFloatValue("divisions")))),
49 _scr_hole(n->getIntValue("screen-hole")),
50 _compression(n->getFloatValue("compression-factor")),
51 _frl(n->getBoolValue("enable-fuselage-ref-line", false)),
52 _target_spot(n->getBoolValue("enable-target-spot", false)),
53 _velocity_vector(n->getBoolValue("enable-velocity-vector", false)),
54 _drift_marker(n->getBoolValue("enable-drift-marker", false)),
55 _alpha_bracket(n->getBoolValue("enable-alpha-bracket", false)),
56 _energy_marker(n->getBoolValue("enable-energy-marker", false)),
57 _climb_dive_marker(n->getBoolValue("enable-climb-dive-marker", false)),
58 _glide_slope_marker(n->getBoolValue("enable-glide-slope-marker",false)),
59 _glide_slope(n->getFloatValue("glide-slope", -4.0)),
60 _energy_worm(n->getBoolValue("enable-energy-marker", false)),
61 _waypoint_marker(n->getBoolValue("enable-waypoint-marker", false)),
62 _zenith(n->getIntValue("zenith")),
63 _nadir(n->getIntValue("nadir")),
64 _hat(n->getIntValue("hat"))
66 const char *t = n->getStringValue("type");
67 _type = strcmp(t, "climb-dive") ? PITCH : CLIMB_DIVE;
72 _vmax = _width_units / 2;
77 void HUD::Ladder::draw(void)
79 if (!_pitch.isValid() || !_roll.isValid())
86 float cosine, sine, xvvr, yvvr, Vxx = 0.0, Vyy = 0.0, Vzz = 0.0;
87 float up_vel, ground_vel, actslope = 0.0;
88 float Axx = 0.0, Ayy = 0.0, Azz = 0.0, total_vel = 0.0, pot_slope, t1;
89 float t2 = 0.0, psi = 0.0, alpha, pla;
90 float vel_x = 0.0, vel_y = 0.0, drift;
91 bool pitch_ladder = false;
92 bool climb_dive_ladder = false;
93 bool clip_plane = false;
95 GLdouble eqn_top[4] = {0.0, -1.0, 0.0, 0.0};
96 GLdouble eqn_left[4] = {-1.0, 0.0, 0.0, 100.0};
97 GLdouble eqn_right[4] = {1.0, 0.0, 0.0, 100.0};
99 Point centroid = get_centroid();
101 float half_span = _w / 2.0;
102 float roll_value = _roll.getFloatValue() * SGD_DEGREES_TO_RADIANS; // FIXME rad/deg conversion
104 pla = get__throttleval();
107 int lgear, wown, wowm, ilcanclaw, ihook;
108 ilcanclaw = get__iaux2();
109 lgear = get__iaux3();
112 ihook = get__iaux6();
114 float pitch_value = _pitch.getFloatValue();
116 if (_type == CLIMB_DIVE) {
117 pitch_ladder = false;
118 climb_dive_ladder = true;
121 } else { // _type == PITCH
123 climb_dive_ladder = false;
127 //**************************************************************
129 // define (0, 0) as center of screen
130 glTranslatef(centroid.x, centroid.y, 0);
132 // OBJECT STATIC RETICLE
133 // TYPE FRL (FUSELAGE REFERENCE LINE)
135 // Draw the FRL spot and line
137 #define FRL_DIAMOND_SIZE 2.0
138 glBegin(GL_LINE_LOOP);
139 glVertex2f(-FRL_DIAMOND_SIZE, 0.0);
140 glVertex2f(0.0, FRL_DIAMOND_SIZE);
141 glVertex2f(FRL_DIAMOND_SIZE, 0.0);
142 glVertex2f(0.0, -FRL_DIAMOND_SIZE);
145 glBegin(GL_LINE_STRIP);
146 glVertex2f(0, FRL_DIAMOND_SIZE);
149 #undef FRL_DIAMOND_SIZE
151 // TYPE WATERLINE_MARK (W shaped _ _ )
154 //****************************************************************
156 // Draw the target spot.
158 #define CENTER_DIAMOND_SIZE 6.0
159 glBegin(GL_LINE_LOOP);
160 glVertex2f(-CENTER_DIAMOND_SIZE, 0.0);
161 glVertex2f(0.0, CENTER_DIAMOND_SIZE);
162 glVertex2f(CENTER_DIAMOND_SIZE, 0.0);
163 glVertex2f(0.0, -CENTER_DIAMOND_SIZE);
165 #undef CENTER_DIAMOND_SIZE
168 //****************************************************************
169 //velocity vector reticle - computations
170 if (_velocity_vector) {
177 psi = get__heading();
182 total_vel = sqrt(Vxx * Vxx + Vyy * Vyy + Vzz * Vzz);
183 ground_vel = sqrt(Vxx * Vxx + Vyy * Vyy);
186 if (ground_vel < 2.0) {
187 if (fabs(up_vel) < 2.0)
190 actslope = (up_vel / fabs(up_vel)) * 90.0;
193 actslope = atan(up_vel / ground_vel) * SGD_RADIANS_TO_DEGREES;
196 xvvr = (((atan2(Vyy, Vxx) * SGD_RADIANS_TO_DEGREES) - psi)
197 * (_compression / globals->get_current_view()->get_aspect_ratio()));
198 drift = ((atan2(Vyy, Vxx) * SGD_RADIANS_TO_DEGREES) - psi);
199 yvvr = ((actslope - pitch_value) * _compression);
200 vel_y = ((actslope - pitch_value) * cos(roll_value) + drift * sin(roll_value)) * _compression;
201 vel_x = (-(actslope - pitch_value) * sin(roll_value) + drift * cos(roll_value))
202 * (_compression / globals->get_current_view()->get_aspect_ratio());
203 // printf("%f %f %f %f\n",vel_x, vel_y, drift, psi);
205 //****************************************************************
206 // OBJECT MOVING RETICLE
207 // TYPE - DRIFT MARKER
211 glBegin(GL_LINE_STRIP);
212 glVertex2f((xvvr * 25 / 120) - 6, -4);
213 glVertex2f(xvvr * 25 / 120, 8);
214 glVertex2f((xvvr * 25 / 120) + 6, -4);
218 //****************************************************************
219 // Clipping coordinates for ladder to be input from xml file
222 glClipPlane(GL_CLIP_PLANE0, eqn_top);
223 glEnable(GL_CLIP_PLANE0);
224 glClipPlane(GL_CLIP_PLANE1, eqn_left);
225 glEnable(GL_CLIP_PLANE1);
226 glClipPlane(GL_CLIP_PLANE2, eqn_right);
227 glEnable(GL_CLIP_PLANE2);
228 // glScissor(-100,-240, 200, 240);
229 // glEnable(GL_SCISSOR_TEST);
232 //****************************************************************
233 // OBJECT MOVING RETICLE
234 // TYPE VELOCITY VECTOR
237 glBegin(GL_LINE_LOOP); // Use polygon to approximate a circle
238 for (count = 0; count < 50; count++) {
239 cosine = 6 * cos(count * SGD_2PI / 50.0);
240 sine = 6 * sin(count * SGD_2PI / 50.0);
241 glVertex2f(cosine + vel_x, sine + vel_y);
245 //velocity vector reticle orientation lines
246 glBegin(GL_LINE_STRIP);
247 glVertex2f(vel_x - 12, vel_y);
248 glVertex2f(vel_x - 6, vel_y);
250 glBegin(GL_LINE_STRIP);
251 glVertex2f(vel_x + 12, vel_y);
252 glVertex2f(vel_x + 6, vel_y);
254 glBegin(GL_LINE_STRIP);
255 glVertex2f(vel_x, vel_y + 12);
256 glVertex2f(vel_x, vel_y + 6);
260 // OBJECT MOVING RETICLE
262 // ATTRIB - ON CONDITION
264 // undercarriage status
265 glBegin(GL_LINE_STRIP);
266 glVertex2f(vel_x + 8, vel_y);
267 glVertex2f(vel_x + 8, vel_y - 4);
270 // OBJECT MOVING RETICLE
272 // ATTRIB - ON CONDITION
273 glBegin(GL_LINE_STRIP);
274 glVertex2f(vel_x - 8, vel_y);
275 glVertex2f(vel_x - 8, vel_y - 4);
278 // OBJECT MOVING RETICLE
280 // ATTRIB - ON CONDITION
281 glBegin(GL_LINE_STRIP);
282 glVertex2f(vel_x, vel_y - 6);
283 glVertex2f(vel_x, vel_y - 10);
287 // OBJECT MOVING RETICLE
289 // ATTRIB - ON CONDITION
291 // arrestor hook status
292 glBegin(GL_LINE_STRIP);
293 glVertex2f(vel_x - 4, vel_y - 8);
294 glVertex2f(vel_x, vel_y - 10);
295 glVertex2f(vel_x + 4, vel_y - 8);
299 } // if _velocity_vector
302 //***************************************************************
303 // OBJECT MOVING RETICLE
304 // TYPE - SQUARE_BRACKET
305 // ATTRIB - ON CONDITION
308 if (_alpha_bracket && ihook == 1) {
309 glBegin(GL_LINE_STRIP);
310 glVertex2f(vel_x - 20 , vel_y - (16 - alpha) * _compression);
311 glVertex2f(vel_x - 17, vel_y - (16 - alpha) * _compression);
312 glVertex2f(vel_x - 17, vel_y - (14 - alpha) * _compression);
313 glVertex2f(vel_x - 20, vel_y - (14 - alpha) * _compression);
316 glBegin(GL_LINE_STRIP);
317 glVertex2f(vel_x + 20 , vel_y - (16 - alpha) * _compression);
318 glVertex2f(vel_x + 17, vel_y - (16 - alpha) * _compression);
319 glVertex2f(vel_x + 17, vel_y - (14 - alpha) * _compression);
320 glVertex2f(vel_x + 20, vel_y - (14 - alpha) * _compression);
324 //printf("xvr=%f, yvr=%f, Vx=%f, Vy=%f, Vz=%f\n",xvvr, yvvr, Vx, Vy, Vz);
325 //printf("Ax=%f, Ay=%f, Az=%f\n",Ax, Ay, Az);
327 //****************************************************************
328 // OBJECT MOVING RETICLE
329 // TYPE ENERGY_MARKERS
331 //energy markers - compute potential slope
332 if (_energy_marker) {
333 if (total_vel < 5.0) {
337 t1 = up_vel / total_vel;
338 t2 = asin((Vxx * Axx + Vyy * Ayy + Vzz * Azz) / (9.81 * total_vel));
340 pot_slope = ((t2 / 3) * SGD_RADIANS_TO_DEGREES) * _compression + vel_y;
341 // if (pot_slope < (vel_y - 45)) pot_slope = vel_y - 45;
342 // if (pot_slope > (vel_y + 45)) pot_slope = vel_y + 45;
345 glBegin(GL_LINE_STRIP);
346 glVertex2f(vel_x - 20, pot_slope - 5);
347 glVertex2f(vel_x - 15, pot_slope);
348 glVertex2f(vel_x - 20, pot_slope + 5);
351 glBegin(GL_LINE_STRIP);
352 glVertex2f(vel_x + 20, pot_slope - 5);
353 glVertex2f(vel_x + 15, pot_slope);
354 glVertex2f(vel_x + 20, pot_slope + 5);
357 if (pla > (105.0 / 131.0)) {
358 glBegin(GL_LINE_STRIP);
359 glVertex2f(vel_x - 24, pot_slope - 5);
360 glVertex2f(vel_x - 19, pot_slope);
361 glVertex2f(vel_x - 24, pot_slope + 5);
364 glBegin(GL_LINE_STRIP);
365 glVertex2f(vel_x + 24, pot_slope - 5);
366 glVertex2f(vel_x + 19, pot_slope);
367 glVertex2f(vel_x + 24, pot_slope + 5);
372 //**********************************************************
374 // OBJECT STATIC RETICLE
376 // ATTRIB - ON CONDITION
378 if (_energy_worm && ilcanclaw == 1) {
379 glBegin(GL_LINE_STRIP);
380 glVertex2f(-15, -134);
381 glVertex2f(15, -134);
384 // OBJECT MOVING RETICLE
386 // ATTRIB - ON CONDITION
387 glBegin(GL_LINE_STRIP);
388 glVertex2f(-6, -134);
389 glVertex2f(-6, t2 * SGD_RADIANS_TO_DEGREES * 4.0 - 134);
390 glVertex2f(+6, t2 * SGD_RADIANS_TO_DEGREES * 4.0 - 134);
394 // OBJECT MOVING RETICLE
396 // ATTRIB - ON CONDITION
397 glBegin(GL_LINE_LOOP);
398 glVertex2f(-6, actslope * 4.0 - 134);
399 glVertex2f(0, actslope * 4.0 -134 + 3);
400 glVertex2f(6, actslope * 4.0 - 134);
401 glVertex2f(0, actslope * 4.0 -134 -3);
406 //*************************************************************
407 // OBJECT MOVING RETICLE
410 // Draw the locked velocity vector.
411 if (_climb_dive_marker) {
412 glBegin(GL_LINE_LOOP);
413 glVertex2f(-3.0, 0.0 + vel_y);
414 glVertex2f(0.0, 6.0 + vel_y);
415 glVertex2f(3.0, 0.0 + vel_y);
416 glVertex2f(0.0, -6.0 + vel_y);
420 //****************************************************************
422 if (climb_dive_ladder) { // CONFORMAL_HUD
423 _vmin = pitch_value - _width_units;
424 _vmax = pitch_value + _width_units;
425 glTranslatef(vel_x, vel_y, 0);
427 } else { // pitch_ladder - Default Hud
428 _vmin = pitch_value - _width_units * 0.5f;
429 _vmax = pitch_value + _width_units * 0.5f;
432 glRotatef(roll_value * SGD_RADIANS_TO_DEGREES, 0.0, 0.0, 1.0);
433 // FRL marker not rotated - this line shifted below
436 const int BUFSIZE = 8;
444 float text_offset = 4.0f;
445 float zero_offset = 0.0;
447 if (climb_dive_ladder)
448 zero_offset = 50.0f; // horizon line is wider by this much (hard coded ??)
452 fntFont *font = _hud->_font_renderer->getFont(); // FIXME
453 float pointsize = _hud->_font_renderer->getPointSize();
454 float italic = _hud->_font_renderer->getSlant();
456 _locTextList.setFont(_hud->_font_renderer);
457 _locTextList.erase();
458 _locLineList.erase();
459 _locStippleLineList.erase();
461 int last = int(_vmax) + 1;
467 for (; i < last; i++) {
468 y = (i - pitch_value) * _compression + .5f;
470 if (!(i % _div_units)) { // At integral multiple of div
471 snprintf(buf, BUFSIZE, "%d", i);
472 font->getBBox(buf, pointsize, italic, &left, &right, &bot, &top);
473 label_length = right + left;
474 label_height = (top + bot) / 2.0f;
479 // Make zero point wider on left
481 x_ini -= zero_offset;
483 // Zero or above draw solid lines
484 draw_line(x_ini, y, x_end, y);
486 if (i == 90 && _zenith == 1)
487 draw_zenith(x_ini, x_end, y);
489 // Below zero draw dashed lines.
490 draw_stipple_line(x_ini, y, x_end, y);
492 if (i == -90 && _nadir ==1)
493 draw_nadir(x_ini, x_end, y);
496 // Calculate the position of the left text and write it.
497 draw_text(x_ini - text_offset - label_length + 2.5/*hack*/, y - label_height, buf);
498 draw_text(x_end + text_offset, y - label_height, buf);
502 } else { // if (_scr_hole)
503 // Draw ladder with space in the middle of the lines
504 float hole = _scr_hole / 2.0f;
506 x_end = -half_span + hole;
507 x_ini2 = half_span - hole;
509 for (; i < last; i++) {
511 y = float(i - pitch_value) * _compression + .5;
512 else // _type == CLIMB_DIVE
513 y = float(i - actslope) * _compression + .5;
515 if (!(i % _div_units)) { // At integral multiple of div
516 snprintf(buf, BUFSIZE, "%d", i);
517 font->getBBox(buf, pointsize, italic, &left, &right, &bot, &top);
518 label_length = right + left;
519 label_height = (top + bot) / 2.0f;
520 //printf("%s -- l %f r %f b %f t %f\n", buf, left, right, bot, top);
522 // Start by calculating the points and drawing the
528 // Make zero point wider on left
530 x_ini -= zero_offset;
531 x_end2 += zero_offset;
533 //draw climb bar vertical lines
534 if (climb_dive_ladder) {
535 // Zero or above draw solid lines
536 draw_line(x_end, y - 5.0, x_end, y);
537 draw_line(x_ini2, y - 5.0, x_ini2, y);
539 // draw pitch / climb bar
540 draw_line(x_ini, y, x_end, y);
541 draw_line(x_ini2, y, x_end2, y);
543 if (i == 90 && _zenith == 1)
544 draw_zenith(x_ini2, x_end, y);
547 // draw dive bar vertical lines
548 if (climb_dive_ladder) {
549 draw_line(x_end, y + 5.0, x_end, y);
550 draw_line(x_ini2, y + 5.0, x_ini2, y);
553 // draw pitch / dive bars
554 draw_stipple_line(x_ini, y, x_end, y);
555 draw_stipple_line(x_ini2, y, x_end2, y);
557 if (i == -90 && _nadir == 1)
558 draw_nadir(x_ini2, x_end, y);
561 // Now calculate the location of the left side label using
562 draw_text(x_ini - text_offset - label_length + 2.5/*hack*/, y - label_height, buf);
563 draw_text(x_end2 + text_offset, y - label_height, buf);
567 // OBJECT LADDER MARK
569 // ATTRIB - ON CONDITION
570 // draw appraoch glide slope marker
572 if (_glide_slope_marker && ihook) {
573 draw_line(-half_span + 15, (_glide_slope - actslope) * _compression,
574 -half_span + hole, (_glide_slope - actslope) * _compression);
575 draw_line(half_span - 15, (_glide_slope - actslope) * _compression,
576 half_span - hole, (_glide_slope - actslope) * _compression);
586 glEnable(GL_LINE_STIPPLE);
587 glLineStipple(1, 0x00FF);
588 _locStippleLineList.draw();
589 glDisable(GL_LINE_STIPPLE);
591 glDisable(GL_CLIP_PLANE0);
592 glDisable(GL_CLIP_PLANE1);
593 glDisable(GL_CLIP_PLANE2);
594 // glDisable(GL_SCISSOR_TEST);
596 //*************************************************************
598 //*************************************************************
600 if (_waypoint_marker) {
601 //waypoint marker computation
602 float fromwp_lat, towp_lat, fromwp_lon, towp_lon, dist, delx, dely, hyp, theta, brg;
604 fromwp_lon = get__longitude() * SGD_DEGREES_TO_RADIANS;
605 fromwp_lat = get__latitude() * SGD_DEGREES_TO_RADIANS;
606 towp_lon = get__aux2() * SGD_DEGREES_TO_RADIANS;
607 towp_lat = get__aux1() * SGD_DEGREES_TO_RADIANS;
609 dist = acos(sin(fromwp_lat) * sin(towp_lat) + cos(fromwp_lat)
610 * cos(towp_lat) * cos(fabs(fromwp_lon - towp_lon)));
611 delx= towp_lat - fromwp_lat;
612 dely = towp_lon - fromwp_lon;
613 hyp = sqrt(pow(delx, 2) + pow(dely, 2));
616 theta = asin(dely / hyp);
620 brg = theta * SGD_RADIANS_TO_DEGREES;
626 // {Brg = asin(cos(towp_lat)*sin(fabs(fromwp_lon-towp_lon))/ sin(dist));
627 // Brg = Brg * SGD_RADIANS_TO_DEGREES; }
629 dist *= SGD_RADIANS_TO_DEGREES * 60.0 * 1852.0; //rad->deg->nm->m
630 // end waypoint marker computation
632 //*********************************************************
633 // OBJECT MOVING RETICLE
636 if (fabs(brg-psi) > 10.0) {
638 glTranslatef(centroid.x, centroid.y, 0);
639 glTranslatef(vel_x, vel_y, 0);
640 glRotatef(brg - psi, 0.0, 0.0, -1.0);
641 glBegin(GL_LINE_LOOP);
642 glVertex2f(-2.5, 20.0);
643 glVertex2f(-2.5, 30.0);
644 glVertex2f(-5.0, 30.0);
645 glVertex2f(0.0, 35.0);
646 glVertex2f(5.0, 30.0);
647 glVertex2f(2.5, 30.0);
648 glVertex2f(2.5, 20.0);
653 // waypoint marker on heading scale
654 if (fabs(brg-psi) < 12.0) {
656 glBegin(GL_LINE_LOOP);
657 glVertex2f(((brg - psi) * 60 / 25) + 320, 240.0);
658 glVertex2f(((brg - psi) * 60 / 25) + 326, 240.0 - 4);
659 glVertex2f(((brg - psi) * 60 / 25) + 323, 240.0 - 4);
660 glVertex2f(((brg - psi) * 60 / 25) + 323, 240.0 - 8);
661 glVertex2f(((brg - psi) * 60 / 25) + 317, 240.0 - 8);
662 glVertex2f(((brg - psi) * 60 / 25) + 317, 240.0 - 4);
663 glVertex2f(((brg - psi) * 60 / 25) + 314, 240.0 - 4);
667 float x = (brg - psi) * 60 / 25 + 320, y = 240.0, r = 5.0;
670 glEnable(GL_POINT_SMOOTH);
673 for (int count = 0; count <= 200; count++) {
674 float temp = count * SG_PI * 3 / (200.0 * 2.0);
675 float temp1 = temp - (45.0 * SGD_DEGREES_TO_RADIANS);
676 x1 = x + r * cos(temp1);
677 y1 = y + r * sin(temp1);
682 glDisable(GL_POINT_SMOOTH);
686 } // if _waypoint_marker
691 /******************************************************************/
692 // draws the zenith symbol for highest possible climb angle (i.e. 90 degree climb angle)
694 void HUD::Ladder::draw_zenith(float xfirst, float xlast, float yvalue)
696 float xcentre = (xfirst + xlast) / 2.0;
697 float ycentre = yvalue;
699 draw_line(xcentre - 9.0, ycentre, xcentre - 3.0, ycentre + 1.3);
700 draw_line(xcentre - 9.0, ycentre, xcentre - 3.0, ycentre - 1.3);
702 draw_line(xcentre + 9.0, ycentre, xcentre + 3.0, ycentre + 1.3);
703 draw_line(xcentre + 9.0, ycentre, xcentre + 3.0, ycentre - 1.3);
705 draw_line(xcentre, ycentre + 9.0, xcentre - 1.3, ycentre + 3.0);
706 draw_line(xcentre, ycentre + 9.0, xcentre + 1.3, ycentre + 3.0);
708 draw_line(xcentre - 3.9, ycentre + 3.9, xcentre - 3.0, ycentre + 1.3);
709 draw_line(xcentre - 3.9, ycentre + 3.9, xcentre - 1.3, ycentre + 3.0);
711 draw_line(xcentre + 3.9, ycentre + 3.9, xcentre + 1.3, ycentre+3.0);
712 draw_line(xcentre + 3.9, ycentre + 3.9, xcentre + 3.0, ycentre+1.3);
714 draw_line(xcentre - 3.9, ycentre - 3.9, xcentre - 3.0, ycentre-1.3);
715 draw_line(xcentre - 3.9, ycentre - 3.9, xcentre - 1.3, ycentre-2.6);
717 draw_line(xcentre + 3.9, ycentre - 3.9, xcentre + 3.0, ycentre-1.3);
718 draw_line(xcentre + 3.9, ycentre - 3.9, xcentre + 1.3, ycentre-2.6);
720 draw_line(xcentre - 1.3, ycentre - 2.6, xcentre, ycentre - 27.0);
721 draw_line(xcentre + 1.3, ycentre - 2.6, xcentre, ycentre - 27.0);
725 // draws the nadir symbol for lowest possible dive angle (i.e. 90 degree dive angle)
727 void HUD::Ladder::draw_nadir(float xfirst, float xlast, float yvalue)
729 float xcentre = (xfirst + xlast) / 2.0;
730 float ycentre = yvalue;
733 float x1, y1, x2, y2;
736 float xcent1, xcent2, ycent1, ycent2;
737 xcent1 = xcentre + r;
740 for (int count = 1; count <= 400; count++) {
741 float temp = count * 2 * SG_PI / 400.0;
742 xcent2 = xcentre + r * cos(temp);
743 ycent2 = ycentre + r * sin(temp);
745 draw_line(xcent1, ycent1, xcent2, ycent2);
751 xcent2 = xcentre + r;
754 Item::draw_line(xcent1, ycent1, xcent2, ycent2); //to connect last point to first point
757 //to draw a line above the circle
758 draw_line(xcentre, ycentre + 7.5, xcentre, ycentre + 22.5);
760 //line in the middle of circle
761 draw_line(xcentre - 7.5, ycentre, xcentre + 7.5, ycentre);
763 float theta = asin(2.5 / 7.5);
764 float theta1 = asin(5.0 / 7.5);
766 x1 = xcentre + r * cos(theta);
768 x2 = xcentre + r * cos((180.0 * SGD_DEGREES_TO_RADIANS) - theta);
770 draw_line(x1, y1, x2, y2);
772 x1 = xcentre + r * cos(theta1);
774 x2 = xcentre + r * cos((180.0 * SGD_DEGREES_TO_RADIANS) - theta1);
776 draw_line(x1, y1, x2, y2);
778 x1 = xcentre + r * cos((180.0 * SGD_DEGREES_TO_RADIANS) + theta);
780 x2 = xcentre + r * cos((360.0 * SGD_DEGREES_TO_RADIANS) - theta);
782 draw_line(x1, y1, x2, y2);
784 x1 = xcentre + r * cos((180.0 * SGD_DEGREES_TO_RADIANS) + theta1);
786 x2 = xcentre + r * cos((360.0 * SGD_DEGREES_TO_RADIANS) - theta1);
788 draw_line(x1, y1, x2, y2);