2 * Copyright (C) Volition, Inc. 1999. All rights reserved.
4 * All source code herein is the property of Volition, Inc. You may not sell
5 * or otherwise commercially exploit the source or things you created based on
10 * $Logfile: /Freespace2/code/Physics/Physics.cpp $
18 * Revision 1.5 2002/07/13 19:47:02 theoddone33
19 * Fix some more warnings
21 * Change demo building, edit Makefile if you want the demo.
23 * Revision 1.4 2002/06/17 06:33:10 relnev
24 * ryan's struct patch for gcc 2.95
26 * Revision 1.3 2002/06/09 04:41:25 relnev
27 * added copyright header
29 * Revision 1.2 2002/05/03 13:34:33 theoddone33
32 * Revision 1.1.1.1 2002/05/03 03:28:10 root
36 * 5 8/13/99 10:49a Andsager
37 * Knossos and HUGE ship warp out. HUGE ship warp in. Stealth search
38 * modes dont collide big ships.
40 * 4 7/03/99 5:50p Dave
41 * Make rotated bitmaps draw properly in padlock views.
43 * 3 5/11/99 10:16p Andsager
44 * First pass on engine wash effect. Rotation (control input), damage,
47 * 2 10/07/98 10:53a Dave
50 * 1 10/07/98 10:50a Dave
52 * 125 8/26/98 4:00p Johnson
53 * Removed max velocity assert so the new huge cap ship can warp in
56 * 124 5/18/98 5:01p Comet
57 * don't do displacement checks in multiplayer
59 * 123 4/06/98 2:38p Duncan
60 * AL: Fix potential negative sqrt due to numerical inaccuracy
62 * 122 3/25/98 1:30p Andsager
63 * comment out physics assert
65 * 121 3/23/98 9:48a Andsager
68 * 120 3/22/98 4:11p Andsager
69 * Remove global Freespace_running
71 * 119 3/20/98 5:15p Andsager
72 * Revised calculation of rotation, shake, and velocity in response to
73 * shockwave since capital ships were seen to shake.
75 * 118 3/19/98 1:06p Andsager
76 * Fix bug checking excessive velocity with accelerated time.
78 * 117 3/17/98 5:43p Andsager
79 * Modify physics checks for very slow frame rates.
81 * 116 3/17/98 9:54a Andsager
82 * Temporary take out Int3()s in velocity checks
84 * 115 3/17/98 9:51a Allender
85 * temporarily commented out Int3 that was causing pain
87 * 114 3/16/98 6:07p Johnson
88 * DA: check that ship velocity does not get too high from collisons
90 * 113 3/16/98 4:39p Adam
91 * change Dave's asserts so that displacement checks don't get used when
94 * 112 3/16/98 1:11p Andsager
95 * Turn on velocity, displacement limit checks
97 * 111 3/12/98 5:21p Andsager
98 * Optimize physics for lasers and dumbfire missiles
100 * 110 3/09/98 2:10p Andsager
101 * Put in checks for debris (other) with excessive velocity.
103 * 109 3/09/98 12:59p Mike
104 * Put error checking in physics code to detect NANs.
106 * 108 3/09/98 12:13a Andsager
107 * Add code to help find jumps in position.
109 * 107 3/03/98 10:39a Andsager
110 * Fixed erroneous mprintf for log term in physics_apply_shock
112 * 106 2/11/98 4:52p Mike
113 * Better attacking by ships.
114 * Fix stupidity in AI classes, which were in backward order!
116 * 105 2/03/98 6:01p Andsager
117 * Fix excessive rotvel in debris_create. Check using physics function
118 * check_rotvel_limit.
120 * 104 2/03/98 10:45a Mike
121 * Comment out mprintf that could occur very often.
123 * 103 1/29/98 2:38p Andsager
124 * Fix bug in physics_apply_shock so that large ships have a smaller
125 * effect from shockwaves.
127 * 102 1/23/98 11:31a Andsager
128 * Added I_body_inv to phys_init. Needed for shockwaves hitting ships in
129 * descent style physics.
131 * 101 1/23/98 9:02a John
132 * Took out Dave's debugging Int3 since they aren't finding what he
133 * thought they would and they broke Testcode and pofview.
135 * 100 1/22/98 5:10p Mike
136 * Fix bug with player's damp getting stuck off.
138 * 99 1/20/98 3:13p Allender
139 * check for Player_obj being valid before doing some other andsager
140 * sanity check in physics_sim_vel
142 * 98 1/20/98 10:08a Andsager
143 * Remove uninitialized viariable warnings.
145 * 97 1/19/98 3:46p Allender
146 * fixed problem where a previous changed caused optimized builds to
147 * break. Don't do a quick out on velcoity_ramp() anymore
149 * 96 1/19/98 12:00p Dave
150 * DA: Revise instantaneous velocity debug check to work with
153 * 95 1/16/98 3:03p Andsager
154 * Fix debug info from int3() on player death.
156 * 94 1/16/98 2:54p Andsager
159 * 93 1/16/98 2:34p Andsager
160 * Added debug code to find instantaneous acceleration.
162 * 92 1/16/98 12:14p Andsager
163 * Add error checking for the current brief stage
165 * 91 12/29/97 5:10p Allender
166 * fixed problems with speed not being reported properly in multiplayer
167 * games. Made read_flying_controls take frametime as a parameter. More
168 * ship/weapon select stuff
170 * 90 12/29/97 12:58p Johnson
171 * don't debug rotational velocity when Fred is running
173 * 89 12/08/97 10:29a Andsager
174 * Remove shockwave physics parameters from weapon_area_apply_blast and
177 * 88 12/05/97 3:31p Andsager
178 * Added view shake if hit by a weapon or collisoin.
180 * 87 12/03/97 5:47p Andsager
181 * Changed reduced damping following collision or weapon to run off time
184 * 86 11/24/97 1:54p Dan
185 * Mike: Comment out Assert() in physics, debug_rotvel().
187 * 85 11/24/97 8:46a Andsager
188 * Added rotational velocity caps and debug info.
190 * 84 11/20/97 4:01p Mike
191 * Prevent divide overflow.
193 * 83 11/20/97 12:34a Mike
194 * Make ships coast to a stop when their engines have been destroyed.
195 * Tricky because code doesn't use damp in forward dimension.
197 * 82 11/19/97 5:57p Mike
198 * Hmm, undid all my changes, except for the crucial removal of a blank
199 * between "physics_sim" and the open paren.
201 * 81 11/19/97 1:26a Andsager
202 * Made shockwaves work again, including shake.
204 * 80 11/17/97 5:15p Andsager
206 * 79 11/13/97 6:01p Andsager
207 * Improve comment in physic_collide_whack
209 * 78 11/13/97 5:41p Andsager
210 * Decreased the rotational whack after getting hit by lasers and
213 * 77 10/29/97 5:01p Andsager
214 * fixed bug in collision physics (physics_collide_whack)
216 * 76 9/16/97 5:28p Andsager
217 * calculate velocity in physics_sim_vel
219 * 75 9/11/97 5:25p Mike
220 * Fix ! vs. & precedence bug in physics_sim_vel().
222 * 74 9/09/97 10:14p Andsager
224 * 73 9/04/97 5:09p Andsager
225 * implement physics using moment of inertia and mass (from BSPgen).
226 * Added to phys_info struct. Updated ship_info, polymodel structs.
227 * Updated weapon ($Mass and $Force) and ship ($Mass -> $Density) tables
229 * 72 9/03/97 5:43p Andsager
230 * fixed bug calculating ramp velocity after getting whacked
232 * 71 9/02/97 4:19p Mike
233 * Comment out code at end of physics_apply_whack() that made ships nearly
236 * 70 8/29/97 10:13a Allender
237 * work on server/client prediction code -- doesn't work too well. Made
238 * all clients simulate their own orientation with the server giving
239 * corrections every so often.
241 * 69 8/25/97 2:41p Andsager
242 * collision code also changes ramp velocity to take account of collison.
243 * some optimization of collision physics.
245 * 68 8/19/97 9:56a John
246 * new thruster effect fairly functional
248 * 67 8/18/97 6:26p Andsager
249 * preliminary version of collision physics
251 * 66 8/17/97 9:19p Andsager
252 * improvement to collision physics
254 * 65 8/13/97 12:16p Andsager
255 * intermediate level checkin for use with collision with extended objects
257 * 64 8/05/97 3:13p Andsager
258 * improved comments to apply_whack
260 * 63 8/05/97 10:18a Lawrance
261 * my_rand() being used temporarily instead of rand()
263 * 62 7/31/97 12:44p Andsager
265 * 61 7/25/97 5:05p John
266 * fixed a potential bug in ramp_velocity when delta dist becomes 0, a
267 * bunch of sideways 8 thingys appear :-)
270 * 60 7/25/97 1:04p Andsager
271 * Modified physics flag PF_REDUCED_DAMP for damping when object is hit.
272 * Flag is now set in physics_apply_whack/shock and turned off in
273 * physics_sim_vel. Weapons should not directly set this flag.
275 * 59 7/25/97 9:07a Andsager
276 * modified apply_whack
278 * 58 7/23/97 5:10p Andsager
279 * Enhanced shockwave effect with shake based on blast force.
281 * 57 7/22/97 2:40p Andsager
282 * shockwaves now cause proper rotation of ships
284 * 56 7/21/97 4:12p Mike
285 * Two ships move as one while docked, including physics whacks. Spin of
286 * objects when killed based on speed.
288 * 55 7/21/97 2:19p John
289 * made descent-style physics work for testcode. fixed bug in the
290 * velocity_ramp code with t==0.0f
292 * 54 7/17/97 8:02p Lawrance
293 * improve comments to physics_apply_whack()
295 * 53 7/16/97 4:42p Mike
296 * Make afterburner shake viewer, not ship.
297 * Shake for limited time.
298 * Add timestamp_until() function to timer library.
300 * 52 7/16/97 11:53a Andsager
302 * 51 7/16/97 11:06a Andsager
303 * Allow damping on z to support shockwaves
305 * 50 7/15/97 12:28p Andsager
306 * commented out some debug code.
308 * 49 7/15/97 12:25p Andsager
309 * More integration with new physics.
311 * 48 7/15/97 12:03p Andsager
314 * 47 7/11/97 11:54a John
315 * added rotated 3d bitmaps.
317 * 46 6/25/97 12:22p Mike
318 * Diminish bashing into of objects. Make ships flying waypoints fly in
321 * 45 6/17/97 10:59p Mike
322 * Comment out irritating mprintf().
324 * 44 6/11/97 4:27p Mike
325 * Balance the whack ships take when they get hit.
327 * 43 4/17/97 10:02a Lawrance
328 * allow ship shaking for ABURN_DECAY_TIME after afterburners cut out
330 * 42 4/16/97 10:48p Mike
332 * Made afterburner engagement a bit in physics flags, removed from ship
333 * flags, removed a parameter to physics_read_flying_controls().
335 * 41 4/11/97 3:17p Mike
336 * Modify physics_sim() to use non quick version of vm_vec_mag(). Quick
337 * version was causing cumulative errors in velocity of homing missiles.
339 * 40 4/10/97 3:20p Mike
340 * Change hull damage to be like shields.
342 * 39 4/04/97 11:08a Adam
343 * played with banking values
345 * 38 4/04/97 12:19a Mike
346 * Make ships bank when they turn.
348 * 37 3/04/97 3:10p Mike
349 * Intermediate checkin: Had to resolve some build errors. Working on two
350 * docked ships moving as one.
352 * 36 2/25/97 7:39p Lawrance
353 * added afterburner_on flag to physics_read_flying_controls() to account
354 * for afterburner effects
356 * 35 2/05/97 6:02p Hoffoss
357 * Added heading rotation around universal Y axis to Fred when controlling
360 * 34 2/05/97 9:15a Mike
361 * Partial implementation of new docking system, integrated so I could
362 * update on John's new turret code.
364 * 33 1/20/97 7:58p John
365 * Fixed some link errors with testcode.
376 #include "floating.h"
378 #include "freespace.h"
379 #include "linklist.h"
383 // defines for physics functions
384 #define MAX_TURN_LIMIT 0.2618f // about 15 degrees
387 #define ROTVEL_TOL 0.1 // Amount of rotvel is decreased if over cap
388 #define ROTVEL_CAP 14.0 // Rotational velocity cap for live objects
389 #define DEAD_ROTVEL_CAP 16.3 // Rotational velocity cap for dead objects
391 #define MAX_SHIP_SPEED 300 // Maximum speed allowed after whack or shockwave
392 #define RESET_SHIP_SPEED 240 // Speed that a ship is reset to after exceeding MAX_SHIP_SPEED
394 #define SW_ROT_FACTOR 5 // increase in rotational time constant in shockwave
395 #define SW_BLAST_DURATION 2000 // maximum duration of shockwave
396 #define REDUCED_DAMP_FACTOR 10 // increase in side_slip and acceleration time constants (scaled according to reduced damp time)
397 #define REDUCED_DAMP_VEL 30 // change in velocity at which reduced_damp_time is 2000 ms
398 #define REDUCED_DAMP_TIME 2000 // ms (2.0 sec)
399 #define WEAPON_SHAKE_TIME 500 // ms (0.5 sec) viewer shake time after hit by weapon (implemented via afterburner shake)
400 #define SPECIAL_WARP_T_CONST 0.651 // special warp time constant (loose 99 % of excess speed in 3 sec)
402 #define PHYS_DEBUG // check if (vel > 500) or (displacement in one frame > 350)
404 void update_reduced_damp_timestamp( physics_info *pi, float impulse );
406 void physics_init( physics_info * pi )
408 memset( pi, 0, sizeof(physics_info) );
410 pi->mass = 10.0f; // This ship weighs 10 units
411 pi->side_slip_time_const = 0.05f;
414 pi->max_vel.xyz.x = 100.0f; //sideways
415 pi->max_vel.xyz.y = 100.0f; //up/down
416 pi->max_vel.xyz.z = 100.0f; //forward
417 pi->max_rear_vel = 100.0f; //backward -- controlled seperately
419 pi->max_rotvel.xyz.x = 2.0f; //pitch
420 pi->max_rotvel.xyz.y = 1.0f; //heading
421 pi->max_rotvel.xyz.z = 2.0f; //bank
423 pi->prev_ramp_vel.xyz.x = 0.0f;
424 pi->prev_ramp_vel.xyz.y = 0.0f;
425 pi->prev_ramp_vel.xyz.z = 0.0f;
427 pi->desired_vel.xyz.x = 0.0f;
428 pi->desired_vel.xyz.y = 0.0f;
429 pi->desired_vel.xyz.z = 0.0f;
431 pi->slide_accel_time_const=pi->side_slip_time_const; // slide using max_vel.xyz.x & .xyz.y
432 pi->slide_decel_time_const=pi->side_slip_time_const; // slide using max_vel.xyz.x & .xyz.y
434 pi->afterburner_decay = 1;
435 pi->forward_thrust = 0.0f;
439 // default values for moment of inetaia
440 (void) vm_vec_make( &pi->I_body_inv.v.rvec, 1e-5f, 0.0f, 0.0f );
441 (void) vm_vec_make( &pi->I_body_inv.v.uvec, 0.0f, 1e-5f, 0.0f );
442 (void) vm_vec_make( &pi->I_body_inv.v.fvec, 0.0f, 0.0f, 1e-5f );
447 //==========================================================================
448 // apply_physics - This does correct physics independent of frame rate.
451 // damping = damping factor. Setting this to zero make the object instantly
452 // go to the target velocity. Increasing it makes the object ramp
453 // up or down to the target velocity.
454 // desired_vel = the target velocity
455 // initial_vel = velocity at last call
456 // t = elapsed time since last call
459 // new_vel = current velocity
460 // delta_pos = delta position (framevec)
461 // You can extend this to 3d by calling it 3 times, once for each x,y,z component.
463 void apply_physics( float damping, float desired_vel, float initial_vel, float t, float * new_vel, float * delta_pos )
465 if ( damping < 0.0001f ) {
467 *delta_pos = desired_vel*t;
469 *new_vel = desired_vel;
472 dv = initial_vel - desired_vel;
473 e = (float)exp( -t/damping );
475 *delta_pos = (1.0f - e)*dv*damping + desired_vel*t;
477 *new_vel = dv*e + desired_vel;
483 float Physics_viewer_bank = 0.0f;
484 int Physics_viewer_direction = PHYSICS_VIEWER_FRONT;
485 static physics_info * Viewer_physics_info = NULL;
487 // If you would like Physics_viewer_bank to be tracked (Which is needed
488 // for rotating 3d bitmaps) call this and pass it a pointer to the
489 // viewer's physics info.
490 void physics_set_viewer( physics_info * p, int dir )
492 if ( (Viewer_physics_info != p) || (Physics_viewer_direction != dir) ) {
493 Viewer_physics_info = p;
494 Physics_viewer_bank = 0.0f;
495 Physics_viewer_direction = dir;
501 // -----------------------------------------------------------------------------------------------------------
502 // add rotational velocity & acceleration
506 void physics_sim_rot(matrix * orient, physics_info * pi, float sim_time )
511 float shock_amplitude;
513 float shock_fraction_time_left;
515 Assert(is_valid_matrix(orient));
516 Assert(is_valid_vec(&pi->rotvel));
517 Assert(is_valid_vec(&pi->desired_rotvel));
519 // Handle special case of shockwave
520 shock_amplitude = 0.0f;
521 if ( pi->flags & PF_IN_SHOCKWAVE ) {
522 if ( timestamp_elapsed(pi->shockwave_decay) ) {
523 pi->flags &= ~PF_IN_SHOCKWAVE;
524 rotdamp = pi->rotdamp;
526 shock_fraction_time_left = timestamp_until( pi->shockwave_decay ) / (float) SW_BLAST_DURATION;
527 rotdamp = pi->rotdamp + pi->rotdamp * (SW_ROT_FACTOR - 1) * shock_fraction_time_left;
528 shock_amplitude = pi->shockwave_shake_amp * shock_fraction_time_left;
531 rotdamp = pi->rotdamp;
534 // Do rotational physics with given damping
535 apply_physics( rotdamp, pi->desired_rotvel.xyz.x, pi->rotvel.xyz.x, sim_time, &new_vel.xyz.x, NULL );
536 apply_physics( rotdamp, pi->desired_rotvel.xyz.y, pi->rotvel.xyz.y, sim_time, &new_vel.xyz.y, NULL );
537 apply_physics( rotdamp, pi->desired_rotvel.xyz.z, pi->rotvel.xyz.z, sim_time, &new_vel.xyz.z, NULL );
541 if (check_rotvel_limit( pi )) {
542 nprintf(("Physics", "rotvel reset in physics_sim_rot\n"));
546 Assert(is_valid_vec(&new_vel));
548 pi->rotvel = new_vel;
550 tangles.p = pi->rotvel.xyz.x*sim_time;
551 tangles.h = pi->rotvel.xyz.y*sim_time;
552 tangles.b = pi->rotvel.xyz.z*sim_time;
554 // If this is the viewer_object, keep track of the
555 // changes in banking so that rotated bitmaps look correct.
556 // This is used by the g3_draw_rotated_bitmap function.
557 if ( pi == Viewer_physics_info ) {
558 switch(Physics_viewer_direction){
559 case PHYSICS_VIEWER_FRONT:
560 Physics_viewer_bank -= tangles.b;
563 case PHYSICS_VIEWER_UP:
564 Physics_viewer_bank -= tangles.h;
567 case PHYSICS_VIEWER_REAR:
568 Physics_viewer_bank += tangles.b;
571 case PHYSICS_VIEWER_LEFT:
572 Physics_viewer_bank += tangles.p;
575 case PHYSICS_VIEWER_RIGHT:
576 Physics_viewer_bank -= tangles.p;
580 Physics_viewer_bank -= tangles.b;
584 if ( Physics_viewer_bank < 0.0f ){
585 Physics_viewer_bank += 2.0f * PI;
588 if ( Physics_viewer_bank > 2.0f * PI ){
589 Physics_viewer_bank -= 2.0f * PI;
593 /* // Make ship shake due to afterburner.
594 if (pi->flags & PF_AFTERBURNER_ON || !timestamp_elapsed(pi->afterburner_decay) ) {
597 max_speed = vm_vec_mag_quick(&pi->max_vel);
598 tangles.p += (float) (rand()-RAND_MAX/2)/RAND_MAX * pi->speed/max_speed/64.0f;
599 tangles.h += (float) (rand()-RAND_MAX/2)/RAND_MAX * pi->speed/max_speed/64.0f;
600 if ( pi->flags & PF_AFTERBURNER_ON ) {
601 pi->afterburner_decay = timestamp(ABURN_DECAY_TIME);
606 // Make ship shake due to shockwave, decreasing in amplitude at the end of the shockwave
607 if ( pi->flags & PF_IN_SHOCKWAVE ) {
608 tangles.p += (float) (myrand()-RAND_MAX/2)/RAND_MAX * shock_amplitude;
609 tangles.h += (float) (myrand()-RAND_MAX/2)/RAND_MAX * shock_amplitude;
613 vm_angles_2_matrix(&pi->last_rotmat, &tangles );
614 vm_matrix_x_matrix( &tmp, orient, &pi->last_rotmat );
617 vm_orthogonalize_matrix(orient);
621 // -----------------------------------------------------------------------------------------------------------
622 // add rotational velocity & acceleration
624 void physics_sim_rot_editor(matrix * orient, physics_info * pi, float sim_time)
631 apply_physics( pi->rotdamp, pi->desired_rotvel.xyz.x, pi->rotvel.xyz.x, sim_time,
632 &new_vel.xyz.x, NULL );
634 apply_physics( pi->rotdamp, pi->desired_rotvel.xyz.y, pi->rotvel.xyz.y, sim_time,
635 &new_vel.xyz.y, NULL );
637 apply_physics( pi->rotdamp, pi->desired_rotvel.xyz.z, pi->rotvel.xyz.z, sim_time,
638 &new_vel.xyz.z, NULL );
640 pi->rotvel = new_vel;
642 tangles.p = pi->rotvel.xyz.x*sim_time;
643 tangles.h = pi->rotvel.xyz.y*sim_time;
644 tangles.b = pi->rotvel.xyz.z*sim_time;
647 t1.h = 0.0f; t1.b = 0.0f;
648 t2.p = 0.0f; t2.b = 0.0f;
650 // put in p & b like normal
651 vm_angles_2_matrix(&pi->last_rotmat, &t1 );
652 vm_matrix_x_matrix( &tmp, orient, &pi->last_rotmat );
654 // Put in heading separately
655 vm_angles_2_matrix(&pi->last_rotmat, &t2 );
656 vm_matrix_x_matrix( orient, &pi->last_rotmat, &tmp );
658 vm_orthogonalize_matrix(orient);
662 // Adds velocity to position
663 // finds velocity and displacement in local coords
664 void physics_sim_vel(vector * position, physics_info * pi, float sim_time, matrix *orient)
666 vector local_disp; // displacement in this frame
667 vector local_v_in; // velocity in local coords at the start of this frame
668 vector local_desired_vel; // desired velocity in local coords
669 vector local_v_out; // velocity in local coords following this frame
672 // Maybe clear the reduced_damp flag.
673 // This fixes the problem of the player getting near-instantaneous acceleration under unknown circumstances.
674 // The larger problem is probably that PF_USE_VEL is getting stuck set.
675 if ((pi->flags & PF_REDUCED_DAMP) && (timestamp_elapsed(pi->reduced_damp_decay))) {
676 pi->flags &= ~PF_REDUCED_DAMP;
679 // Set up damping constants based on special conditions
680 // ie. shockwave, collision, weapon, dead
681 if (pi->flags & PF_DEAD_DAMP) {
682 // side_slip_time_const is already quite large and now needs to be applied in all directions
683 (void) vm_vec_make( &damp, pi->side_slip_time_const, pi->side_slip_time_const, pi->side_slip_time_const );
685 } else if (pi->flags & PF_REDUCED_DAMP) {
686 // case of shock, weapon, collide, etc.
687 if ( timestamp_elapsed(pi->reduced_damp_decay) ) {
688 (void) vm_vec_make( &damp, pi->side_slip_time_const, pi->side_slip_time_const, 0.0f );
690 // damp is multiplied by fraction and not fraction^2, gives better collision separation
691 float reduced_damp_fraction_time_left = timestamp_until( pi->reduced_damp_decay ) / (float) REDUCED_DAMP_TIME;
692 damp.xyz.x = pi->side_slip_time_const * ( 1 + (REDUCED_DAMP_FACTOR-1) * reduced_damp_fraction_time_left );
693 damp.xyz.y = pi->side_slip_time_const * ( 1 + (REDUCED_DAMP_FACTOR-1) * reduced_damp_fraction_time_left );
694 damp.xyz.z = pi->side_slip_time_const * reduced_damp_fraction_time_left * REDUCED_DAMP_FACTOR;
698 (void) vm_vec_make( &damp, pi->side_slip_time_const, pi->side_slip_time_const, 0.0f );
701 // Note: CANNOT maintain a *local velocity* since a rotation can occur in this frame.
702 // thus the local velocity of in the next frame can be different (this would require rotate to change local vel
703 // and this is not desired
705 // get local components of current velocity
706 vm_vec_rotate (&local_v_in, &pi->vel, orient);
708 // get local components of desired velocity
709 vm_vec_rotate (&local_desired_vel, &pi->desired_vel, orient);
711 // find updated LOCAL velocity and position in the local x direction
712 apply_physics (damp.xyz.x, local_desired_vel.xyz.x, local_v_in.xyz.x, sim_time, &local_v_out.xyz.x, &local_disp.xyz.x);
714 // find updated LOCAL velocity and position in the local y direction
715 apply_physics (damp.xyz.y, local_desired_vel.xyz.y, local_v_in.xyz.y, sim_time, &local_v_out.xyz.y, &local_disp.xyz.y);
717 // find updated LOCAL velocity and position in the local z direction
718 // for player ship, damp should normally be zero, but may be altered in a shockwave
719 // in death, shockwave,etc. we want damping time const large for all 3 axes
720 // warp in test - make excessive speed drop exponentially from max allowed
721 // become (0.01x in 3 sec)
723 int special_warp_in = FALSE;
724 float excess = local_v_in.xyz.z - pi->max_vel.xyz.z;
725 if (excess > 5 && (pi->flags & PF_SPECIAL_WARP_IN)) {
726 special_warp_in = TRUE;
727 float exp_factor = float(exp(-sim_time / SPECIAL_WARP_T_CONST));
728 local_v_out.xyz.z = pi->max_vel.xyz.z + excess * exp_factor;
729 local_disp.xyz.z = (pi->max_vel.xyz.z * sim_time) + excess * (float(SPECIAL_WARP_T_CONST) * (1.0f - exp_factor));
730 } else if (pi->flags & PF_SPECIAL_WARP_OUT) {
731 float exp_factor = float(exp(-sim_time / SPECIAL_WARP_T_CONST));
733 vm_vec_rotate(&temp, &pi->prev_ramp_vel, orient);
734 float deficeit = temp.xyz.z - local_v_in.xyz.z;
735 local_v_out.xyz.z = local_v_in.xyz.z + deficeit * (1.0f - exp_factor);
736 local_disp.xyz.z = (local_v_in.xyz.z * sim_time) + deficeit * (sim_time - (float(SPECIAL_WARP_T_CONST) * (1.0f - exp_factor)));
738 apply_physics (damp.xyz.z, local_desired_vel.xyz.z, local_v_in.xyz.z, sim_time, &local_v_out.xyz.z, &local_disp.xyz.z);
741 // maybe turn off special warp in flag
742 if ((pi->flags & PF_SPECIAL_WARP_IN) && (excess < 5)) {
743 pi->flags &= ~(PF_SPECIAL_WARP_IN);
746 // update world position from local to world coords using orient
748 vm_vec_unrotate (&world_disp, &local_disp, orient);
750 // check for excess velocity or translation
752 if ( (Game_mode & GM_IN_MISSION) && (Game_mode & GM_NORMAL) ) {
753 // Assert( (sim_time > 0.5f) || (vm_vec_mag_squared(&pi->vel) < 500*500) );
754 // Assert( (sim_time > 0.5f) || (vm_vec_mag_squared(&world_disp) < 350*350) );
757 vm_vec_add2 (position, &world_disp);
759 // update world velocity
760 vm_vec_unrotate(&pi->vel, &local_v_out, orient);
762 if (special_warp_in) {
763 vm_vec_rotate(&pi->prev_ramp_vel, &pi->vel, orient);
767 // -----------------------------------------------------------------------------------------------------------
768 // Simulate a physics object for this frame
769 void physics_sim(vector* position, matrix* orient, physics_info* pi, float sim_time)
771 // check flag which tells us whether or not to do velocity translation
772 if (pi->flags & PF_CONST_VEL) {
773 vm_vec_scale_add2(position, &pi->vel, sim_time);
775 physics_sim_vel(position, pi, sim_time, orient);
777 physics_sim_rot(orient, pi, sim_time);
779 pi->speed = vm_vec_mag(&pi->vel); // Note, cannot use quick version, causes cumulative error, increasing speed.
780 pi->fspeed = vm_vec_dot(&orient->v.fvec, &pi->vel); // instead of vector magnitude -- use only forward vector since we are only interested in forward velocity
785 // -----------------------------------------------------------------------------------------------------------
786 // Simulate a physics object for this frame. Used by the editor. The difference between
787 // this function and physics_sim() is that this one uses a heading change to rotate around
788 // the universal Y axis, rather than the local orientation's Y axis. Banking is also ignored.
789 void physics_sim_editor(vector *position, matrix * orient, physics_info * pi, float sim_time )
791 physics_sim_vel(position, pi, sim_time, orient);
792 physics_sim_rot_editor(orient, pi, sim_time);
793 pi->speed = vm_vec_mag_quick(&pi->vel);
794 pi->fspeed = vm_vec_dot(&orient->v.fvec, &pi->vel); // instead of vector magnitude -- use only forward vector since we are only interested in forward velocity
797 // function to predict an object's position given the delta time and an objects physics info
798 void physics_predict_pos(physics_info *pi, float delta_time, vector *predicted_pos)
800 apply_physics( pi->side_slip_time_const, pi->desired_vel.xyz.x, pi->vel.xyz.x, delta_time,
801 NULL, &predicted_pos->xyz.x );
803 apply_physics( pi->side_slip_time_const, pi->desired_vel.xyz.y, pi->vel.xyz.y, delta_time,
804 NULL, &predicted_pos->xyz.y );
806 apply_physics( pi->side_slip_time_const, pi->desired_vel.xyz.z, pi->vel.xyz.z, delta_time,
807 NULL, &predicted_pos->xyz.z );
810 // function to predict an object's velocity given the parameters
811 void physics_predict_vel(physics_info *pi, float delta_time, vector *predicted_vel)
813 if (pi->flags & PF_CONST_VEL) {
814 predicted_vel = &pi->vel;
816 apply_physics( pi->side_slip_time_const, pi->desired_vel.xyz.x, pi->vel.xyz.x, delta_time,
817 &predicted_vel->xyz.x, NULL );
819 apply_physics( pi->side_slip_time_const, pi->desired_vel.xyz.y, pi->vel.xyz.y, delta_time,
820 &predicted_vel->xyz.y, NULL );
822 apply_physics( pi->side_slip_time_const, pi->desired_vel.xyz.z, pi->vel.xyz.z, delta_time,
823 &predicted_vel->xyz.z, NULL );
827 // function to predict position and velocity of an object
828 void physics_predict_pos_and_vel(physics_info *pi, float delta_time, vector *predicted_vel, vector *predicted_pos)
831 apply_physics( pi->side_slip_time_const, pi->desired_vel.xyz.x, pi->vel.xyz.x, delta_time,
832 &predicted_vel->xyz.x, &predicted_pos->xyz.x );
834 apply_physics( pi->side_slip_time_const, pi->desired_vel.xyz.y, pi->vel.xyz.y, delta_time,
835 &predicted_vel->xyz.y, &predicted_pos->xyz.y );
837 apply_physics( pi->side_slip_time_const, pi->desired_vel.xyz.z, pi->vel.xyz.z, delta_time,
838 &predicted_vel->xyz.z, &predicted_pos->xyz.z );
841 // physics_read_flying_controls()
843 // parmeters: *orient ==>
846 // Adam: Uncomment-out this define to enable banking while turning.
847 #define BANK_WHEN_TURN
851 // function looks at the flying controls and the current velocity to determine a goal velocity
852 // function determines velocity in object's reference frame and goal velocity in object's reference frame
853 void physics_read_flying_controls( matrix * orient, physics_info * pi, control_info * ci, float sim_time, vector *wash_rot)
855 vector goal_vel; // goal velocity in local coords, *not* accounting for ramping of velcity
856 float ramp_time_const; // time constant for velocity ramping
858 float velocity_ramp (float v_in, float v_goal, float time_const, float t);
860 // if ( keyd_pressed[KEY_LSHIFT] ) {
861 // keyd_pressed[KEY_LSHIFT] = 0;
865 ci->forward += (ci->forward_cruise_percent / 100.0f);
867 // mprintf(("ci->forward == %7.3f\n", ci->forward));
869 // give control imput to cause rotation in engine wash
871 if ( wash_rot && Wash_on ) {
872 ci->pitch += wash_rot->xyz.x;
873 ci->bank += wash_rot->xyz.z;
874 ci->heading += wash_rot->xyz.y;
877 if (ci->pitch > 1.0f ) ci->pitch = 1.0f;
878 else if (ci->pitch < -1.0f ) ci->pitch = -1.0f;
880 if (ci->vertical > 1.0f ) ci->vertical = 1.0f;
881 else if (ci->vertical < -1.0f ) ci->vertical = -1.0f;
883 if (ci->heading > 1.0f ) ci->heading = 1.0f;
884 else if (ci->heading < -1.0f ) ci->heading = -1.0f;
886 if (ci->sideways > 1.0f ) ci->sideways = 1.0f;
887 else if (ci->sideways < -1.0f ) ci->sideways = -1.0f;
889 if (ci->bank > 1.0f ) ci->bank = 1.0f;
890 else if (ci->bank < -1.0f ) ci->bank = -1.0f;
892 if ( pi->flags & PF_AFTERBURNER_ON )
895 if (ci->forward > 1.0f ) ci->forward = 1.0f;
896 else if (ci->forward < -1.0f ) ci->forward = -1.0f;
898 pi->desired_rotvel.xyz.x = ci->pitch * pi->max_rotvel.xyz.x;
899 pi->desired_rotvel.xyz.y = ci->heading * pi->max_rotvel.xyz.y;
903 #ifdef BANK_WHEN_TURN
904 // To change direction of bank, negate the whole expression.
905 // To increase magnitude of banking, decrease denominator.
906 // Adam: The following statement is all the math for banking while turning.
907 delta_bank = - (ci->heading * pi->max_rotvel.xyz.y)/2.0f;
912 pi->desired_rotvel.xyz.z = ci->bank * pi->max_rotvel.xyz.z + delta_bank;
913 pi->forward_thrust = ci->forward;
915 if ( pi->flags & PF_AFTERBURNER_ON ) {
916 goal_vel.xyz.x = ci->sideways*pi->afterburner_max_vel.xyz.x;
917 goal_vel.xyz.y = ci->vertical*pi->afterburner_max_vel.xyz.y;
918 goal_vel.xyz.z = ci->forward* pi->afterburner_max_vel.xyz.z;
921 goal_vel.xyz.x = ci->sideways*pi->max_vel.xyz.x;
922 goal_vel.xyz.y = ci->vertical*pi->max_vel.xyz.y;
923 goal_vel.xyz.z = ci->forward* pi->max_vel.xyz.z;
926 if ( goal_vel.xyz.z < -pi->max_rear_vel )
927 goal_vel.xyz.z = -pi->max_rear_vel;
930 if ( pi->flags & PF_ACCELERATES ) {
932 // Determine *resultant* DESIRED VELOCITY (desired_vel) accounting for RAMPING of velocity
933 // Use LOCAL coordinates
934 // if slide_enabled, ramp velocity for x and y, otherwise set goal (0)
935 // always ramp velocity for z
938 // If reduced damp in effect, then adjust ramp_velocity and desired_velocity can not change as fast.
939 // Scale according to reduced_damp_time_expansion.
940 float reduced_damp_ramp_time_expansion;
941 if ( pi->flags & PF_REDUCED_DAMP ) {
942 float reduced_damp_fraction_time_left = timestamp_until( pi->reduced_damp_decay ) / (float) REDUCED_DAMP_TIME;
943 reduced_damp_ramp_time_expansion = 1.0f + (REDUCED_DAMP_FACTOR-1) * reduced_damp_fraction_time_left;
945 reduced_damp_ramp_time_expansion = 1.0f;
948 // if ( !use_descent && (Player_obj->phys_info.forward_accel_time_const < 0.1) && !(Ships[Player_obj->instance].flags & SF_DYING) && (Player_obj->type != OBJ_OBSERVER) )
949 // Int3(); // Get dave A
951 if (pi->flags & PF_SLIDE_ENABLED) {
952 // determine the local velocity
953 // deterimine whether accelerating or decleration toward goal for x
954 if ( goal_vel.xyz.x > 0.0f ) {
955 if ( goal_vel.xyz.x >= pi->prev_ramp_vel.xyz.x )
956 ramp_time_const = pi->slide_accel_time_const;
958 ramp_time_const = pi->slide_decel_time_const;
959 } else { // goal_vel.xyz.x <= 0.0
960 if ( goal_vel.xyz.x <= pi->prev_ramp_vel.xyz.x )
961 ramp_time_const = pi->slide_accel_time_const;
963 ramp_time_const = pi->slide_decel_time_const;
965 // If reduced damp in effect, then adjust ramp_velocity and desired_velocity can not change as fast
966 if ( pi->flags & PF_REDUCED_DAMP ) {
967 ramp_time_const *= reduced_damp_ramp_time_expansion;
969 pi->prev_ramp_vel.xyz.x = velocity_ramp(pi->prev_ramp_vel.xyz.x, goal_vel.xyz.x, ramp_time_const, sim_time);
971 // deterimine whether accelerating or decleration toward goal for y
972 if ( goal_vel.xyz.y > 0.0f ) {
973 if ( goal_vel.xyz.y >= pi->prev_ramp_vel.xyz.y )
974 ramp_time_const = pi->slide_accel_time_const;
976 ramp_time_const = pi->slide_decel_time_const;
977 } else { // goal_vel.xyz.y <= 0.0
978 if ( goal_vel.xyz.y <= pi->prev_ramp_vel.xyz.y )
979 ramp_time_const = pi->slide_accel_time_const;
981 ramp_time_const = pi->slide_decel_time_const;
983 // If reduced damp in effect, then adjust ramp_velocity and desired_velocity can not change as fast
984 if ( pi->flags & PF_REDUCED_DAMP ) {
985 ramp_time_const *= reduced_damp_ramp_time_expansion;
987 pi->prev_ramp_vel.xyz.y = velocity_ramp( pi->prev_ramp_vel.xyz.y, goal_vel.xyz.y, ramp_time_const, sim_time);
990 pi->prev_ramp_vel.xyz.x = 0.0f;
991 pi->prev_ramp_vel.xyz.y = 0.0f;
994 // find ramp velocity in the forward direction
995 if ( goal_vel.xyz.z >= pi->prev_ramp_vel.xyz.z ) {
996 if ( pi->flags & PF_AFTERBURNER_ON )
997 ramp_time_const = pi->afterburner_forward_accel_time_const;
999 ramp_time_const = pi->forward_accel_time_const;
1001 ramp_time_const = pi->forward_decel_time_const;
1003 // If reduced damp in effect, then adjust ramp_velocity and desired_velocity can not change as fast
1004 if ( pi->flags & PF_REDUCED_DAMP ) {
1005 ramp_time_const *= reduced_damp_ramp_time_expansion;
1007 pi->prev_ramp_vel.xyz.z = velocity_ramp( pi->prev_ramp_vel.xyz.z, goal_vel.xyz.z, ramp_time_const, sim_time);
1010 // this translates local desired velocities to world velocities
1012 vm_vec_zero(&pi->desired_vel);
1013 vm_vec_scale_add2( &pi->desired_vel, &orient->v.rvec, pi->prev_ramp_vel.xyz.x );
1014 vm_vec_scale_add2( &pi->desired_vel, &orient->v.uvec, pi->prev_ramp_vel.xyz.y );
1015 vm_vec_scale_add2( &pi->desired_vel, &orient->v.fvec, pi->prev_ramp_vel.xyz.z );
1016 } else // object does not accelerate (PF_ACCELERATES not set)
1017 pi->desired_vel = pi->vel;
1022 // ----------------------------------------------------------------
1023 // Do *dest = *delta unless:
1024 // *delta is pretty small
1025 // and they are of different signs.
1026 void physics_set_rotvel_and_saturate(float *dest, float delta)
1029 if ((delta ^ *dest) < 0) {
1030 if (abs(delta) < F1_0/8) {
1031 // mprintf((0, "D"));
1034 // mprintf((0, "d"));
1037 // mprintf((0, "!"));
1045 // ----------------------------------------------------------------------------
1046 // physics_apply_whack applies an instaneous whack on an object changing
1047 // both the objects velocity and the rotational velocity based on the impulse
1050 // input: impulse => impulse vector ( force*time = impulse = change in momentum (mv) )
1051 // pos => vector from center of mass to location of where the force acts
1052 // pi => pointer to phys_info struct of object getting whacked
1053 // orient => orientation matrix (needed to set rotational impulse in body coords)
1054 // mass => mass of the object (may be different from pi.mass if docked)
1056 #define WHACK_LIMIT 0.001f
1057 #define ROTVEL_WHACK_CONST 0.12
1058 void physics_apply_whack(vector *impulse, vector *pos, physics_info *pi, matrix *orient, float mass)
1060 vector local_torque, torque;
1063 // Detect null vector.
1064 if ((fl_abs(impulse->xyz.x) <= WHACK_LIMIT) && (fl_abs(impulse->xyz.y) <= WHACK_LIMIT) && (fl_abs(impulse->xyz.z) <= WHACK_LIMIT))
1067 // first do the rotational velocity
1068 // calculate the torque on the body based on the point on the
1069 // object that was hit and the momentum being applied to the object
1071 vm_vec_crossprod(&torque, pos, impulse);
1072 vm_vec_rotate ( &local_torque, &torque, orient );
1074 vector delta_rotvel;
1075 vm_vec_rotate( &delta_rotvel, &local_torque, &pi->I_body_inv );
1076 vm_vec_scale ( &delta_rotvel, (float) ROTVEL_WHACK_CONST );
1077 vm_vec_add2( &pi->rotvel, &delta_rotvel );
1080 if (check_rotvel_limit( pi )) {
1081 nprintf(("Physics", "rotvel reset in physics_apply_whack\n"));
1085 //mprintf(("Whack: %7.3f %7.3f %7.3f\n", pi->rotvel.xyz.x, pi->rotvel.xyz.y, pi->rotvel.xyz.z));
1087 // instant whack on the velocity
1088 // reduce damping on all axes
1089 pi->flags |= PF_REDUCED_DAMP;
1090 update_reduced_damp_timestamp( pi, vm_vec_mag(impulse) );
1092 // find time for shake from weapon to end
1093 int dtime = timestamp_until(pi->afterburner_decay);
1094 if (dtime < WEAPON_SHAKE_TIME) {
1095 pi->afterburner_decay = timestamp( WEAPON_SHAKE_TIME );
1098 vm_vec_scale_add2( &pi->vel, impulse, 1.0f / pi->mass );
1099 if (!(pi->flags & PF_USE_VEL) && (vm_vec_mag_squared(&pi->vel) > MAX_SHIP_SPEED*MAX_SHIP_SPEED)) {
1101 nprintf(("Physics", "speed reset in physics_apply_whack [speed: %f]\n", vm_vec_mag(&pi->vel)));
1103 vm_vec_normalize(&pi->vel);
1104 vm_vec_scale(&pi->vel, (float)RESET_SHIP_SPEED);
1106 vm_vec_rotate( &pi->prev_ramp_vel, &pi->vel, orient ); // set so velocity will ramp starting from current speed
1107 // ramped velocity is now affected by collision
1110 // function generates a velocity ramp with a given time constant independent of frame rate
1111 // uses an exponential approach to desired velocity and a cheat when close to improve closure speed
1112 float velocity_ramp (float v_in, float v_goal, float ramp_time_const, float t)
1118 // JAS: If no time elapsed, change nothing
1122 delta_v = v_goal - v_in;
1123 dist = (float)fl_abs(delta_v);
1125 // hack to speed up closure when close to goal
1126 if (dist < ramp_time_const/3)
1127 ramp_time_const = dist / 3;
1129 // Rather than get a divide by zero, just go to the goal
1130 if ( ramp_time_const < 0.0001f ) {
1134 // determine decay factor (ranges from 0 for short times to 1 for long times)
1135 // when decay factor is near 0, the velocity in nearly unchanged
1136 // when decay factor in near 1, the velocity approaches goal
1137 decay_factor = (float)exp(- t / ramp_time_const);
1139 return (v_in + delta_v * (1.0f - decay_factor) );
1143 // ----------------------------------------------------------------------------
1144 // physics_apply_shock applies applies a shockwave to an object. This causes a velocity impulse and
1145 // and a rotational impulse. This is different than physics_apply_whack since a shock wave is a pressure
1146 // wave which acts over the *surface* of the object, not a point.
1148 // inputs: direction_vec => a position vector whose direction is from the center of the shock wave to the object
1149 // pressure => the pressure of the shock wave at the object
1150 // pi => physics_info structure
1151 // orient => matrix orientation of the object
1152 // min => vector of minimum values of the bounding box
1153 // max => vector of maximum values of the bounding box
1154 // radius => bounding box radius of the object, used for scaling rotation
1156 // outputs: makes changes to physics_info structure rotvel and vel variables
1158 #define STD_PRESSURE 1000 // amplitude of standard shockwave blasts
1159 #define MIN_RADIUS 10 // radius within which full rotvel and shake applied
1160 #define MAX_RADIUS 50 // radius at which no rotvel or shake applied
1161 #define MAX_ROTVEL 0.4 // max rotational velocity
1162 #define MAX_SHAKE 0.1 // max rotational amplitude of shake
1163 #define MAX_VEL 8 // max vel from shockwave
1164 void physics_apply_shock(vector *direction_vec, float pressure, physics_info *pi, matrix *orient, vector *min, vector *max, float radius)
1167 vector local_torque, temp_torque, torque;
1172 if (radius > MAX_RADIUS) {
1176 vm_vec_normalize_safe ( direction_vec );
1178 area.xyz.x = (max->xyz.y - min->xyz.z) * (max->xyz.z - min->xyz.z);
1179 area.xyz.y = (max->xyz.x - min->xyz.x) * (max->xyz.z - min->xyz.z);
1180 area.xyz.z = (max->xyz.x - min->xyz.x) * (max->xyz.y - min->xyz.y);
1182 normal.xyz.x = vm_vec_dotprod( direction_vec, &orient->v.rvec );
1183 normal.xyz.y = vm_vec_dotprod( direction_vec, &orient->v.uvec );
1184 normal.xyz.z = vm_vec_dotprod( direction_vec, &orient->v.fvec );
1186 sin.xyz.x = fl_sqrt( fl_abs(1.0f - normal.xyz.x*normal.xyz.x) );
1187 sin.xyz.y = fl_sqrt( fl_abs(1.0f - normal.xyz.y*normal.xyz.y) );
1188 sin.xyz.z = fl_sqrt( fl_abs(1.0f - normal.xyz.z*normal.xyz.z) );
1190 (void) vm_vec_make( &torque, 0.0f, 0.0f, 0.0f );
1192 // find the torque exerted due to the shockwave hitting each face
1193 // model the effect of the shockwave as if the shockwave were a plane of projectiles,
1194 // all moving in the direction direction_vec. then find the torque as the cross prod
1195 // of the force (pressure * area * normal * sin * scale * mass)
1196 // normal takes account the fraction of the surface exposed to the shockwave
1197 // the sin term is not technically needed but "feels" better
1198 // scale factors out the increase in area with larger objects
1199 // more massive objects get less rotation
1201 // find torque due to forces on the right/left face
1202 if ( normal.xyz.x < 0.0f ) // normal < 0, hits the right face
1203 vm_vec_copy_scale( &impact_vec, &orient->v.rvec, max->xyz.x * pressure * area.xyz.x * normal.xyz.x * sin.xyz.x / pi->mass );
1204 else // normal > 0, hits the left face
1205 vm_vec_copy_scale( &impact_vec, &orient->v.rvec, min->xyz.x * pressure * area.xyz.x * -normal.xyz.x * sin.xyz.x / pi->mass );
1207 vm_vec_crossprod( &temp_torque, &impact_vec, direction_vec );
1208 vm_vec_add2( &torque, &temp_torque );
1210 // find torque due to forces on the up/down face
1211 if ( normal.xyz.y < 0.0f )
1212 vm_vec_copy_scale( &impact_vec, &orient->v.uvec, max->xyz.y * pressure * area.xyz.y * normal.xyz.y * sin.xyz.y / pi->mass );
1214 vm_vec_copy_scale( &impact_vec, &orient->v.uvec, min->xyz.y * pressure * area.xyz.y * -normal.xyz.y * sin.xyz.y / pi->mass );
1216 vm_vec_crossprod( &temp_torque, &impact_vec, direction_vec );
1217 vm_vec_add2( &torque, &temp_torque );
1219 // find torque due to forces on the forward/backward face
1220 if ( normal.xyz.z < 0.0f )
1221 vm_vec_copy_scale( &impact_vec, &orient->v.fvec, max->xyz.z * pressure * area.xyz.z * normal.xyz.z * sin.xyz.z / pi->mass );
1223 vm_vec_copy_scale( &impact_vec, &orient->v.fvec, min->xyz.z * pressure * area.xyz.z * -normal.xyz.z * sin.xyz.z / pi->mass );
1225 vm_vec_crossprod( &temp_torque, &impact_vec, direction_vec );
1226 vm_vec_add2( &torque, &temp_torque );
1228 // compute delta rotvel, scale according to blast and radius
1230 vector delta_rotvel;
1231 vm_vec_rotate( &local_torque, &torque, orient );
1232 vm_vec_copy_normalize(&delta_rotvel, &local_torque);
1233 if (radius < MIN_RADIUS) {
1236 scale = (MAX_RADIUS - radius)/(MAX_RADIUS-MIN_RADIUS);
1238 vm_vec_scale(&delta_rotvel, (float)(MAX_ROTVEL*(pressure/STD_PRESSURE)*scale));
1239 // nprintf(("Physics", "rotvel scale %f\n", (MAX_ROTVEL*(pressure/STD_PRESSURE)*scale)));
1240 vm_vec_add2(&pi->rotvel, &delta_rotvel);
1242 // set shockwave shake amplitude, duration, flag
1243 pi->shockwave_shake_amp = (float)(MAX_SHAKE*(pressure/STD_PRESSURE)*scale);
1244 pi->shockwave_decay = timestamp( SW_BLAST_DURATION );
1245 pi->flags |= PF_IN_SHOCKWAVE;
1247 // set reduced translational damping, set flags
1248 float velocity_scale = (float)MAX_VEL*scale;
1249 pi->flags |= PF_REDUCED_DAMP;
1250 update_reduced_damp_timestamp( pi, velocity_scale*pi->mass );
1251 vm_vec_scale_add2( &pi->vel, direction_vec, velocity_scale );
1252 vm_vec_rotate(&pi->prev_ramp_vel, &pi->vel, orient); // set so velocity will ramp starting from current speed
1254 // check that kick from shockwave is not too large
1255 if (!(pi->flags & PF_USE_VEL) && (vm_vec_mag_squared(&pi->vel) > MAX_SHIP_SPEED*MAX_SHIP_SPEED)) {
1257 nprintf(("Physics", "speed reset in physics_apply_shock [speed: %f]\n", vm_vec_mag(&pi->vel)));
1259 vm_vec_normalize(&pi->vel);
1260 vm_vec_scale(&pi->vel, (float)RESET_SHIP_SPEED);
1264 if (check_rotvel_limit( pi )) {
1265 nprintf(("Physics", "rotvel reset in physics_apply_shock\n"));
1269 // ramped velocity is now affected by collision
1272 // ----------------------------------------------------------------------------
1273 // physics_collide_whack applies an instaneous whack on an object changing
1274 // both the objects velocity and the rotational velocity based on the impulse
1277 // input: impulse => impulse vector ( force*time = impulse = change in momentum (mv) )
1278 // world_delta_rotvel => change in rotational velocity (already calculated)
1279 // pi => pointer to phys_info struct of object getting whacked
1280 // orient => orientation matrix (needed to set rotational impulse in body coords)
1283 // Warning: Do not change ROTVEL_COLLIDE_WHACK_CONST. This will mess up collision physics.
1284 // If you need to change the rotation, change COLLISION_ROTATION_FACTOR in collide_ship_ship.
1285 #define ROTVEL_COLLIDE_WHACK_CONST 1.0
1286 void physics_collide_whack( vector *impulse, vector *world_delta_rotvel, physics_info *pi, matrix *orient )
1288 vector body_delta_rotvel;
1290 // Detect null vector.
1291 if ((fl_abs(impulse->xyz.x) <= WHACK_LIMIT) && (fl_abs(impulse->xyz.y) <= WHACK_LIMIT) && (fl_abs(impulse->xyz.z) <= WHACK_LIMIT))
1294 vm_vec_rotate( &body_delta_rotvel, world_delta_rotvel, orient );
1295 // vm_vec_scale( &body_delta_rotvel, (float) ROTVEL_COLLIDE_WHACK_CONST );
1296 vm_vec_add2( &pi->rotvel, &body_delta_rotvel );
1299 if (check_rotvel_limit( pi )) {
1300 nprintf(("Physics", "rotvel reset in physics_collide_whack\n"));
1304 update_reduced_damp_timestamp( pi, vm_vec_mag(impulse) );
1306 // find time for shake from weapon to end
1307 int dtime = timestamp_until(pi->afterburner_decay);
1308 if (dtime < WEAPON_SHAKE_TIME) {
1309 pi->afterburner_decay = timestamp( WEAPON_SHAKE_TIME );
1312 pi->flags |= PF_REDUCED_DAMP;
1313 vm_vec_scale_add2( &pi->vel, impulse, 1.0f / pi->mass );
1314 // check that collision does not give ship too much speed
1315 // reset if too high
1316 if (!(pi->flags & PF_USE_VEL) && (vm_vec_mag_squared(&pi->vel) > MAX_SHIP_SPEED*MAX_SHIP_SPEED)) {
1318 nprintf(("Physics", "speed reset in physics_collide_whack [speed: %f]\n", vm_vec_mag(&pi->vel)));
1320 vm_vec_normalize(&pi->vel);
1321 vm_vec_scale(&pi->vel, (float)RESET_SHIP_SPEED);
1323 vm_vec_rotate( &pi->prev_ramp_vel, &pi->vel, orient ); // set so velocity will ramp starting from current speed
1324 // ramped velocity is now affected by collision
1325 // rotate previous ramp velocity (in model coord) to be same as vel (in world coords)
1329 int check_rotvel_limit( physics_info *pi )
1331 if ( 0 == pi->flags ) // weapon
1337 int change_made = 0;
1338 if ( !(pi->flags & PF_DEAD_DAMP) ) {
1339 // case of normal, live ship
1340 // -- Commented out by MK: Assert( vm_vec_mag_squared(&pi->max_rotvel) > ROTVEL_TOL );
1341 // Assert( (pi->max_rotvel.xyz.x <= ROTVEL_CAP) && (pi->max_rotvel.xyz.y <= ROTVEL_CAP) && (pi->max_rotvel.xyz.z <= ROTVEL_CAP) );
1342 // Warning(LOCATION,"Excessive rotvel (wx: %f, wy: %f, wz:%f)\n", pi->rotvel.xyz.x, pi->rotvel.xyz.y, pi->rotvel.xyz.z);
1343 if ( fl_abs(pi->rotvel.xyz.x) > pi->max_rotvel.xyz.x ) {
1344 pi->rotvel.xyz.x = (pi->rotvel.xyz.x / fl_abs(pi->rotvel.xyz.x)) * (pi->max_rotvel.xyz.x - (float) ROTVEL_TOL);
1347 if ( fl_abs(pi->rotvel.xyz.y) > pi->max_rotvel.xyz.y ) {
1348 pi->rotvel.xyz.y = (pi->rotvel.xyz.y / fl_abs(pi->rotvel.xyz.y)) * (pi->max_rotvel.xyz.y - (float) ROTVEL_TOL);
1351 if ( fl_abs(pi->rotvel.xyz.z) > pi->max_rotvel.xyz.z ) {
1352 pi->rotvel.xyz.z = (pi->rotvel.xyz.z / fl_abs(pi->rotvel.xyz.z)) * (pi->max_rotvel.xyz.z - (float) ROTVEL_TOL);
1356 // case of dead ship
1357 if ( fl_abs(pi->rotvel.xyz.x) > DEAD_ROTVEL_CAP ) {
1358 pi->rotvel.xyz.x = (pi->rotvel.xyz.x / fl_abs(pi->rotvel.xyz.x)) * (float) (DEAD_ROTVEL_CAP - ROTVEL_TOL);
1361 if ( fl_abs(pi->rotvel.xyz.y) > DEAD_ROTVEL_CAP ) {
1362 pi->rotvel.xyz.y = (pi->rotvel.xyz.y / fl_abs(pi->rotvel.xyz.y)) * (float) (DEAD_ROTVEL_CAP - ROTVEL_TOL);
1365 if ( fl_abs(pi->rotvel.xyz.z) > DEAD_ROTVEL_CAP ) {
1366 pi->rotvel.xyz.z = (pi->rotvel.xyz.z / fl_abs(pi->rotvel.xyz.z)) * (float) (DEAD_ROTVEL_CAP - ROTVEL_TOL);
1373 // ----------------------------------------------------------------------------
1374 // update_reduced_damp_timestamp()
1376 void update_reduced_damp_timestamp( physics_info *pi, float impulse )
1379 // Compute duration of reduced damp from present
1380 // Compare with current value and increase if greater, otherwise ignore
1381 int reduced_damp_decay_time;
1382 reduced_damp_decay_time = (int) (REDUCED_DAMP_TIME * impulse / (REDUCED_DAMP_VEL * pi->mass));
1383 if ( reduced_damp_decay_time > REDUCED_DAMP_TIME )
1384 reduced_damp_decay_time = REDUCED_DAMP_TIME;
1386 // Reset timestamp if larger than current (if any)
1387 if ( timestamp_valid( pi->reduced_damp_decay ) ) {
1388 int time_left = timestamp_until( pi->reduced_damp_decay );
1389 if ( time_left > 0 ) {
1390 // increment old time, but apply cap
1391 int new_time = reduced_damp_decay_time + time_left;
1392 if ( new_time < REDUCED_DAMP_TIME ) {
1393 pi->reduced_damp_decay = timestamp( new_time );
1396 pi->reduced_damp_decay = timestamp( reduced_damp_decay_time );
1400 pi->reduced_damp_decay = timestamp( reduced_damp_decay_time );