2 * $Logfile: /Freespace2/code/Physics/Physics.cpp $
10 * Revision 1.1 2002/05/03 03:28:10 root
14 * 5 8/13/99 10:49a Andsager
15 * Knossos and HUGE ship warp out. HUGE ship warp in. Stealth search
16 * modes dont collide big ships.
18 * 4 7/03/99 5:50p Dave
19 * Make rotated bitmaps draw properly in padlock views.
21 * 3 5/11/99 10:16p Andsager
22 * First pass on engine wash effect. Rotation (control input), damage,
25 * 2 10/07/98 10:53a Dave
28 * 1 10/07/98 10:50a Dave
30 * 125 8/26/98 4:00p Johnson
31 * Removed max velocity assert so the new huge cap ship can warp in
34 * 124 5/18/98 5:01p Comet
35 * don't do displacement checks in multiplayer
37 * 123 4/06/98 2:38p Duncan
38 * AL: Fix potential negative sqrt due to numerical inaccuracy
40 * 122 3/25/98 1:30p Andsager
41 * comment out physics assert
43 * 121 3/23/98 9:48a Andsager
46 * 120 3/22/98 4:11p Andsager
47 * Remove global Freespace_running
49 * 119 3/20/98 5:15p Andsager
50 * Revised calculation of rotation, shake, and velocity in response to
51 * shockwave since capital ships were seen to shake.
53 * 118 3/19/98 1:06p Andsager
54 * Fix bug checking excessive velocity with accelerated time.
56 * 117 3/17/98 5:43p Andsager
57 * Modify physics checks for very slow frame rates.
59 * 116 3/17/98 9:54a Andsager
60 * Temporary take out Int3()s in velocity checks
62 * 115 3/17/98 9:51a Allender
63 * temporarily commented out Int3 that was causing pain
65 * 114 3/16/98 6:07p Johnson
66 * DA: check that ship velocity does not get too high from collisons
68 * 113 3/16/98 4:39p Adam
69 * change Dave's asserts so that displacement checks don't get used when
72 * 112 3/16/98 1:11p Andsager
73 * Turn on velocity, displacement limit checks
75 * 111 3/12/98 5:21p Andsager
76 * Optimize physics for lasers and dumbfire missiles
78 * 110 3/09/98 2:10p Andsager
79 * Put in checks for debris (other) with excessive velocity.
81 * 109 3/09/98 12:59p Mike
82 * Put error checking in physics code to detect NANs.
84 * 108 3/09/98 12:13a Andsager
85 * Add code to help find jumps in position.
87 * 107 3/03/98 10:39a Andsager
88 * Fixed erroneous mprintf for log term in physics_apply_shock
90 * 106 2/11/98 4:52p Mike
91 * Better attacking by ships.
92 * Fix stupidity in AI classes, which were in backward order!
94 * 105 2/03/98 6:01p Andsager
95 * Fix excessive rotvel in debris_create. Check using physics function
98 * 104 2/03/98 10:45a Mike
99 * Comment out mprintf that could occur very often.
101 * 103 1/29/98 2:38p Andsager
102 * Fix bug in physics_apply_shock so that large ships have a smaller
103 * effect from shockwaves.
105 * 102 1/23/98 11:31a Andsager
106 * Added I_body_inv to phys_init. Needed for shockwaves hitting ships in
107 * descent style physics.
109 * 101 1/23/98 9:02a John
110 * Took out Dave's debugging Int3 since they aren't finding what he
111 * thought they would and they broke Testcode and pofview.
113 * 100 1/22/98 5:10p Mike
114 * Fix bug with player's damp getting stuck off.
116 * 99 1/20/98 3:13p Allender
117 * check for Player_obj being valid before doing some other andsager
118 * sanity check in physics_sim_vel
120 * 98 1/20/98 10:08a Andsager
121 * Remove uninitialized viariable warnings.
123 * 97 1/19/98 3:46p Allender
124 * fixed problem where a previous changed caused optimized builds to
125 * break. Don't do a quick out on velcoity_ramp() anymore
127 * 96 1/19/98 12:00p Dave
128 * DA: Revise instantaneous velocity debug check to work with
131 * 95 1/16/98 3:03p Andsager
132 * Fix debug info from int3() on player death.
134 * 94 1/16/98 2:54p Andsager
137 * 93 1/16/98 2:34p Andsager
138 * Added debug code to find instantaneous acceleration.
140 * 92 1/16/98 12:14p Andsager
141 * Add error checking for the current brief stage
143 * 91 12/29/97 5:10p Allender
144 * fixed problems with speed not being reported properly in multiplayer
145 * games. Made read_flying_controls take frametime as a parameter. More
146 * ship/weapon select stuff
148 * 90 12/29/97 12:58p Johnson
149 * don't debug rotational velocity when Fred is running
151 * 89 12/08/97 10:29a Andsager
152 * Remove shockwave physics parameters from weapon_area_apply_blast and
155 * 88 12/05/97 3:31p Andsager
156 * Added view shake if hit by a weapon or collisoin.
158 * 87 12/03/97 5:47p Andsager
159 * Changed reduced damping following collision or weapon to run off time
162 * 86 11/24/97 1:54p Dan
163 * Mike: Comment out Assert() in physics, debug_rotvel().
165 * 85 11/24/97 8:46a Andsager
166 * Added rotational velocity caps and debug info.
168 * 84 11/20/97 4:01p Mike
169 * Prevent divide overflow.
171 * 83 11/20/97 12:34a Mike
172 * Make ships coast to a stop when their engines have been destroyed.
173 * Tricky because code doesn't use damp in forward dimension.
175 * 82 11/19/97 5:57p Mike
176 * Hmm, undid all my changes, except for the crucial removal of a blank
177 * between "physics_sim" and the open paren.
179 * 81 11/19/97 1:26a Andsager
180 * Made shockwaves work again, including shake.
182 * 80 11/17/97 5:15p Andsager
184 * 79 11/13/97 6:01p Andsager
185 * Improve comment in physic_collide_whack
187 * 78 11/13/97 5:41p Andsager
188 * Decreased the rotational whack after getting hit by lasers and
191 * 77 10/29/97 5:01p Andsager
192 * fixed bug in collision physics (physics_collide_whack)
194 * 76 9/16/97 5:28p Andsager
195 * calculate velocity in physics_sim_vel
197 * 75 9/11/97 5:25p Mike
198 * Fix ! vs. & precedence bug in physics_sim_vel().
200 * 74 9/09/97 10:14p Andsager
202 * 73 9/04/97 5:09p Andsager
203 * implement physics using moment of inertia and mass (from BSPgen).
204 * Added to phys_info struct. Updated ship_info, polymodel structs.
205 * Updated weapon ($Mass and $Force) and ship ($Mass -> $Density) tables
207 * 72 9/03/97 5:43p Andsager
208 * fixed bug calculating ramp velocity after getting whacked
210 * 71 9/02/97 4:19p Mike
211 * Comment out code at end of physics_apply_whack() that made ships nearly
214 * 70 8/29/97 10:13a Allender
215 * work on server/client prediction code -- doesn't work too well. Made
216 * all clients simulate their own orientation with the server giving
217 * corrections every so often.
219 * 69 8/25/97 2:41p Andsager
220 * collision code also changes ramp velocity to take account of collison.
221 * some optimization of collision physics.
223 * 68 8/19/97 9:56a John
224 * new thruster effect fairly functional
226 * 67 8/18/97 6:26p Andsager
227 * preliminary version of collision physics
229 * 66 8/17/97 9:19p Andsager
230 * improvement to collision physics
232 * 65 8/13/97 12:16p Andsager
233 * intermediate level checkin for use with collision with extended objects
235 * 64 8/05/97 3:13p Andsager
236 * improved comments to apply_whack
238 * 63 8/05/97 10:18a Lawrance
239 * my_rand() being used temporarily instead of rand()
241 * 62 7/31/97 12:44p Andsager
243 * 61 7/25/97 5:05p John
244 * fixed a potential bug in ramp_velocity when delta dist becomes 0, a
245 * bunch of sideways 8 thingys appear :-)
248 * 60 7/25/97 1:04p Andsager
249 * Modified physics flag PF_REDUCED_DAMP for damping when object is hit.
250 * Flag is now set in physics_apply_whack/shock and turned off in
251 * physics_sim_vel. Weapons should not directly set this flag.
253 * 59 7/25/97 9:07a Andsager
254 * modified apply_whack
256 * 58 7/23/97 5:10p Andsager
257 * Enhanced shockwave effect with shake based on blast force.
259 * 57 7/22/97 2:40p Andsager
260 * shockwaves now cause proper rotation of ships
262 * 56 7/21/97 4:12p Mike
263 * Two ships move as one while docked, including physics whacks. Spin of
264 * objects when killed based on speed.
266 * 55 7/21/97 2:19p John
267 * made descent-style physics work for testcode. fixed bug in the
268 * velocity_ramp code with t==0.0f
270 * 54 7/17/97 8:02p Lawrance
271 * improve comments to physics_apply_whack()
273 * 53 7/16/97 4:42p Mike
274 * Make afterburner shake viewer, not ship.
275 * Shake for limited time.
276 * Add timestamp_until() function to timer library.
278 * 52 7/16/97 11:53a Andsager
280 * 51 7/16/97 11:06a Andsager
281 * Allow damping on z to support shockwaves
283 * 50 7/15/97 12:28p Andsager
284 * commented out some debug code.
286 * 49 7/15/97 12:25p Andsager
287 * More integration with new physics.
289 * 48 7/15/97 12:03p Andsager
292 * 47 7/11/97 11:54a John
293 * added rotated 3d bitmaps.
295 * 46 6/25/97 12:22p Mike
296 * Diminish bashing into of objects. Make ships flying waypoints fly in
299 * 45 6/17/97 10:59p Mike
300 * Comment out irritating mprintf().
302 * 44 6/11/97 4:27p Mike
303 * Balance the whack ships take when they get hit.
305 * 43 4/17/97 10:02a Lawrance
306 * allow ship shaking for ABURN_DECAY_TIME after afterburners cut out
308 * 42 4/16/97 10:48p Mike
310 * Made afterburner engagement a bit in physics flags, removed from ship
311 * flags, removed a parameter to physics_read_flying_controls().
313 * 41 4/11/97 3:17p Mike
314 * Modify physics_sim() to use non quick version of vm_vec_mag(). Quick
315 * version was causing cumulative errors in velocity of homing missiles.
317 * 40 4/10/97 3:20p Mike
318 * Change hull damage to be like shields.
320 * 39 4/04/97 11:08a Adam
321 * played with banking values
323 * 38 4/04/97 12:19a Mike
324 * Make ships bank when they turn.
326 * 37 3/04/97 3:10p Mike
327 * Intermediate checkin: Had to resolve some build errors. Working on two
328 * docked ships moving as one.
330 * 36 2/25/97 7:39p Lawrance
331 * added afterburner_on flag to physics_read_flying_controls() to account
332 * for afterburner effects
334 * 35 2/05/97 6:02p Hoffoss
335 * Added heading rotation around universal Y axis to Fred when controlling
338 * 34 2/05/97 9:15a Mike
339 * Partial implementation of new docking system, integrated so I could
340 * update on John's new turret code.
342 * 33 1/20/97 7:58p John
343 * Fixed some link errors with testcode.
354 #include "floating.h"
356 #include "freespace.h"
357 #include "linklist.h"
361 // defines for physics functions
362 #define MAX_TURN_LIMIT 0.2618f // about 15 degrees
365 #define ROTVEL_TOL 0.1 // Amount of rotvel is decreased if over cap
366 #define ROTVEL_CAP 14.0 // Rotational velocity cap for live objects
367 #define DEAD_ROTVEL_CAP 16.3 // Rotational velocity cap for dead objects
369 #define MAX_SHIP_SPEED 300 // Maximum speed allowed after whack or shockwave
370 #define RESET_SHIP_SPEED 240 // Speed that a ship is reset to after exceeding MAX_SHIP_SPEED
372 #define SW_ROT_FACTOR 5 // increase in rotational time constant in shockwave
373 #define SW_BLAST_DURATION 2000 // maximum duration of shockwave
374 #define REDUCED_DAMP_FACTOR 10 // increase in side_slip and acceleration time constants (scaled according to reduced damp time)
375 #define REDUCED_DAMP_VEL 30 // change in velocity at which reduced_damp_time is 2000 ms
376 #define REDUCED_DAMP_TIME 2000 // ms (2.0 sec)
377 #define WEAPON_SHAKE_TIME 500 // ms (0.5 sec) viewer shake time after hit by weapon (implemented via afterburner shake)
378 #define SPECIAL_WARP_T_CONST 0.651 // special warp time constant (loose 99 % of excess speed in 3 sec)
380 #define PHYS_DEBUG // check if (vel > 500) or (displacement in one frame > 350)
382 void update_reduced_damp_timestamp( physics_info *pi, float impulse );
384 void physics_init( physics_info * pi )
386 memset( pi, 0, sizeof(physics_info) );
388 pi->mass = 10.0f; // This ship weighs 10 units
389 pi->side_slip_time_const = 0.05f;
392 pi->max_vel.x = 100.0f; //sideways
393 pi->max_vel.y = 100.0f; //up/down
394 pi->max_vel.z = 100.0f; //forward
395 pi->max_rear_vel = 100.0f; //backward -- controlled seperately
397 pi->max_rotvel.x = 2.0f; //pitch
398 pi->max_rotvel.y = 1.0f; //heading
399 pi->max_rotvel.z = 2.0f; //bank
401 pi->prev_ramp_vel.x = 0.0f;
402 pi->prev_ramp_vel.y = 0.0f;
403 pi->prev_ramp_vel.z = 0.0f;
405 pi->desired_vel.x = 0.0f;
406 pi->desired_vel.y = 0.0f;
407 pi->desired_vel.z = 0.0f;
409 pi->slide_accel_time_const=pi->side_slip_time_const; // slide using max_vel.x & .y
410 pi->slide_decel_time_const=pi->side_slip_time_const; // slide using max_vel.x & .y
412 pi->afterburner_decay = 1;
413 pi->forward_thrust = 0.0f;
417 // default values for moment of inetaia
418 vm_vec_make( &pi->I_body_inv.rvec, 1e-5f, 0.0f, 0.0f );
419 vm_vec_make( &pi->I_body_inv.uvec, 0.0f, 1e-5f, 0.0f );
420 vm_vec_make( &pi->I_body_inv.fvec, 0.0f, 0.0f, 1e-5f );
425 //==========================================================================
426 // apply_physics - This does correct physics independent of frame rate.
429 // damping = damping factor. Setting this to zero make the object instantly
430 // go to the target velocity. Increasing it makes the object ramp
431 // up or down to the target velocity.
432 // desired_vel = the target velocity
433 // initial_vel = velocity at last call
434 // t = elapsed time since last call
437 // new_vel = current velocity
438 // delta_pos = delta position (framevec)
439 // You can extend this to 3d by calling it 3 times, once for each x,y,z component.
441 void apply_physics( float damping, float desired_vel, float initial_vel, float t, float * new_vel, float * delta_pos )
443 if ( damping < 0.0001f ) {
445 *delta_pos = desired_vel*t;
447 *new_vel = desired_vel;
450 dv = initial_vel - desired_vel;
451 e = (float)exp( -t/damping );
453 *delta_pos = (1.0f - e)*dv*damping + desired_vel*t;
455 *new_vel = dv*e + desired_vel;
461 float Physics_viewer_bank = 0.0f;
462 int Physics_viewer_direction = PHYSICS_VIEWER_FRONT;
463 static physics_info * Viewer_physics_info = NULL;
465 // If you would like Physics_viewer_bank to be tracked (Which is needed
466 // for rotating 3d bitmaps) call this and pass it a pointer to the
467 // viewer's physics info.
468 void physics_set_viewer( physics_info * p, int dir )
470 if ( (Viewer_physics_info != p) || (Physics_viewer_direction != dir) ) {
471 Viewer_physics_info = p;
472 Physics_viewer_bank = 0.0f;
473 Physics_viewer_direction = dir;
479 // -----------------------------------------------------------------------------------------------------------
480 // add rotational velocity & acceleration
484 void physics_sim_rot(matrix * orient, physics_info * pi, float sim_time )
489 float shock_amplitude;
491 float shock_fraction_time_left;
493 Assert(is_valid_matrix(orient));
494 Assert(is_valid_vec(&pi->rotvel));
495 Assert(is_valid_vec(&pi->desired_rotvel));
497 // Handle special case of shockwave
498 shock_amplitude = 0.0f;
499 if ( pi->flags & PF_IN_SHOCKWAVE ) {
500 if ( timestamp_elapsed(pi->shockwave_decay) ) {
501 pi->flags &= ~PF_IN_SHOCKWAVE;
502 rotdamp = pi->rotdamp;
504 shock_fraction_time_left = timestamp_until( pi->shockwave_decay ) / (float) SW_BLAST_DURATION;
505 rotdamp = pi->rotdamp + pi->rotdamp * (SW_ROT_FACTOR - 1) * shock_fraction_time_left;
506 shock_amplitude = pi->shockwave_shake_amp * shock_fraction_time_left;
509 rotdamp = pi->rotdamp;
512 // Do rotational physics with given damping
513 apply_physics( rotdamp, pi->desired_rotvel.x, pi->rotvel.x, sim_time, &new_vel.x, NULL );
514 apply_physics( rotdamp, pi->desired_rotvel.y, pi->rotvel.y, sim_time, &new_vel.y, NULL );
515 apply_physics( rotdamp, pi->desired_rotvel.z, pi->rotvel.z, sim_time, &new_vel.z, NULL );
519 if (check_rotvel_limit( pi )) {
520 nprintf(("Physics", "rotvel reset in physics_sim_rot\n"));
524 Assert(is_valid_vec(&new_vel));
526 pi->rotvel = new_vel;
528 tangles.p = pi->rotvel.x*sim_time;
529 tangles.h = pi->rotvel.y*sim_time;
530 tangles.b = pi->rotvel.z*sim_time;
532 // If this is the viewer_object, keep track of the
533 // changes in banking so that rotated bitmaps look correct.
534 // This is used by the g3_draw_rotated_bitmap function.
535 if ( pi == Viewer_physics_info ) {
536 switch(Physics_viewer_direction){
537 case PHYSICS_VIEWER_FRONT:
538 Physics_viewer_bank -= tangles.b;
541 case PHYSICS_VIEWER_UP:
542 Physics_viewer_bank -= tangles.h;
545 case PHYSICS_VIEWER_REAR:
546 Physics_viewer_bank += tangles.b;
549 case PHYSICS_VIEWER_LEFT:
550 Physics_viewer_bank += tangles.p;
553 case PHYSICS_VIEWER_RIGHT:
554 Physics_viewer_bank -= tangles.p;
558 Physics_viewer_bank -= tangles.b;
562 if ( Physics_viewer_bank < 0.0f ){
563 Physics_viewer_bank += 2.0f * PI;
566 if ( Physics_viewer_bank > 2.0f * PI ){
567 Physics_viewer_bank -= 2.0f * PI;
571 /* // Make ship shake due to afterburner.
572 if (pi->flags & PF_AFTERBURNER_ON || !timestamp_elapsed(pi->afterburner_decay) ) {
575 max_speed = vm_vec_mag_quick(&pi->max_vel);
576 tangles.p += (float) (rand()-RAND_MAX/2)/RAND_MAX * pi->speed/max_speed/64.0f;
577 tangles.h += (float) (rand()-RAND_MAX/2)/RAND_MAX * pi->speed/max_speed/64.0f;
578 if ( pi->flags & PF_AFTERBURNER_ON ) {
579 pi->afterburner_decay = timestamp(ABURN_DECAY_TIME);
584 // Make ship shake due to shockwave, decreasing in amplitude at the end of the shockwave
585 if ( pi->flags & PF_IN_SHOCKWAVE ) {
586 tangles.p += (float) (myrand()-RAND_MAX/2)/RAND_MAX * shock_amplitude;
587 tangles.h += (float) (myrand()-RAND_MAX/2)/RAND_MAX * shock_amplitude;
591 vm_angles_2_matrix(&pi->last_rotmat, &tangles );
592 vm_matrix_x_matrix( &tmp, orient, &pi->last_rotmat );
595 vm_orthogonalize_matrix(orient);
599 // -----------------------------------------------------------------------------------------------------------
600 // add rotational velocity & acceleration
602 void physics_sim_rot_editor(matrix * orient, physics_info * pi, float sim_time)
609 apply_physics( pi->rotdamp, pi->desired_rotvel.x, pi->rotvel.x, sim_time,
612 apply_physics( pi->rotdamp, pi->desired_rotvel.y, pi->rotvel.y, sim_time,
615 apply_physics( pi->rotdamp, pi->desired_rotvel.z, pi->rotvel.z, sim_time,
618 pi->rotvel = new_vel;
620 tangles.p = pi->rotvel.x*sim_time;
621 tangles.h = pi->rotvel.y*sim_time;
622 tangles.b = pi->rotvel.z*sim_time;
625 t1.h = 0.0f; t1.b = 0.0f;
626 t2.p = 0.0f; t2.b = 0.0f;
628 // put in p & b like normal
629 vm_angles_2_matrix(&pi->last_rotmat, &t1 );
630 vm_matrix_x_matrix( &tmp, orient, &pi->last_rotmat );
632 // Put in heading separately
633 vm_angles_2_matrix(&pi->last_rotmat, &t2 );
634 vm_matrix_x_matrix( orient, &pi->last_rotmat, &tmp );
636 vm_orthogonalize_matrix(orient);
640 // Adds velocity to position
641 // finds velocity and displacement in local coords
642 void physics_sim_vel(vector * position, physics_info * pi, float sim_time, matrix *orient)
644 vector local_disp; // displacement in this frame
645 vector local_v_in; // velocity in local coords at the start of this frame
646 vector local_desired_vel; // desired velocity in local coords
647 vector local_v_out; // velocity in local coords following this frame
650 // Maybe clear the reduced_damp flag.
651 // This fixes the problem of the player getting near-instantaneous acceleration under unknown circumstances.
652 // The larger problem is probably that PF_USE_VEL is getting stuck set.
653 if ((pi->flags & PF_REDUCED_DAMP) && (timestamp_elapsed(pi->reduced_damp_decay))) {
654 pi->flags &= ~PF_REDUCED_DAMP;
657 // Set up damping constants based on special conditions
658 // ie. shockwave, collision, weapon, dead
659 if (pi->flags & PF_DEAD_DAMP) {
660 // side_slip_time_const is already quite large and now needs to be applied in all directions
661 vm_vec_make( &damp, pi->side_slip_time_const, pi->side_slip_time_const, pi->side_slip_time_const );
663 } else if (pi->flags & PF_REDUCED_DAMP) {
664 // case of shock, weapon, collide, etc.
665 if ( timestamp_elapsed(pi->reduced_damp_decay) ) {
666 vm_vec_make( &damp, pi->side_slip_time_const, pi->side_slip_time_const, 0.0f );
668 // damp is multiplied by fraction and not fraction^2, gives better collision separation
669 float reduced_damp_fraction_time_left = timestamp_until( pi->reduced_damp_decay ) / (float) REDUCED_DAMP_TIME;
670 damp.x = pi->side_slip_time_const * ( 1 + (REDUCED_DAMP_FACTOR-1) * reduced_damp_fraction_time_left );
671 damp.y = pi->side_slip_time_const * ( 1 + (REDUCED_DAMP_FACTOR-1) * reduced_damp_fraction_time_left );
672 damp.z = pi->side_slip_time_const * reduced_damp_fraction_time_left * REDUCED_DAMP_FACTOR;
676 vm_vec_make( &damp, pi->side_slip_time_const, pi->side_slip_time_const, 0.0f );
679 // Note: CANNOT maintain a *local velocity* since a rotation can occur in this frame.
680 // thus the local velocity of in the next frame can be different (this would require rotate to change local vel
681 // and this is not desired
683 // get local components of current velocity
684 vm_vec_rotate (&local_v_in, &pi->vel, orient);
686 // get local components of desired velocity
687 vm_vec_rotate (&local_desired_vel, &pi->desired_vel, orient);
689 // find updated LOCAL velocity and position in the local x direction
690 apply_physics (damp.x, local_desired_vel.x, local_v_in.x, sim_time, &local_v_out.x, &local_disp.x);
692 // find updated LOCAL velocity and position in the local y direction
693 apply_physics (damp.y, local_desired_vel.y, local_v_in.y, sim_time, &local_v_out.y, &local_disp.y);
695 // find updated LOCAL velocity and position in the local z direction
696 // for player ship, damp should normally be zero, but may be altered in a shockwave
697 // in death, shockwave,etc. we want damping time const large for all 3 axes
698 // warp in test - make excessive speed drop exponentially from max allowed
699 // become (0.01x in 3 sec)
701 int special_warp_in = FALSE;
702 float excess = local_v_in.z - pi->max_vel.z;
703 if (excess > 5 && (pi->flags & PF_SPECIAL_WARP_IN)) {
704 special_warp_in = TRUE;
705 float exp_factor = float(exp(-sim_time / SPECIAL_WARP_T_CONST));
706 local_v_out.z = pi->max_vel.z + excess * exp_factor;
707 local_disp.z = (pi->max_vel.z * sim_time) + excess * (float(SPECIAL_WARP_T_CONST) * (1.0f - exp_factor));
708 } else if (pi->flags & PF_SPECIAL_WARP_OUT) {
709 float exp_factor = float(exp(-sim_time / SPECIAL_WARP_T_CONST));
711 vm_vec_rotate(&temp, &pi->prev_ramp_vel, orient);
712 float deficeit = temp.z - local_v_in.z;
713 local_v_out.z = local_v_in.z + deficeit * (1.0f - exp_factor);
714 local_disp.z = (local_v_in.z * sim_time) + deficeit * (sim_time - (float(SPECIAL_WARP_T_CONST) * (1.0f - exp_factor)));
716 apply_physics (damp.z, local_desired_vel.z, local_v_in.z, sim_time, &local_v_out.z, &local_disp.z);
719 // maybe turn off special warp in flag
720 if ((pi->flags & PF_SPECIAL_WARP_IN) && (excess < 5)) {
721 pi->flags &= ~(PF_SPECIAL_WARP_IN);
724 // update world position from local to world coords using orient
726 vm_vec_unrotate (&world_disp, &local_disp, orient);
728 // check for excess velocity or translation
730 if ( (Game_mode & GM_IN_MISSION) && (Game_mode & GM_NORMAL) ) {
731 // Assert( (sim_time > 0.5f) || (vm_vec_mag_squared(&pi->vel) < 500*500) );
732 // Assert( (sim_time > 0.5f) || (vm_vec_mag_squared(&world_disp) < 350*350) );
735 vm_vec_add2 (position, &world_disp);
737 // update world velocity
738 vm_vec_unrotate(&pi->vel, &local_v_out, orient);
740 if (special_warp_in) {
741 vm_vec_rotate(&pi->prev_ramp_vel, &pi->vel, orient);
745 // -----------------------------------------------------------------------------------------------------------
746 // Simulate a physics object for this frame
747 void physics_sim(vector* position, matrix* orient, physics_info* pi, float sim_time)
749 // check flag which tells us whether or not to do velocity translation
750 if (pi->flags & PF_CONST_VEL) {
751 vm_vec_scale_add2(position, &pi->vel, sim_time);
753 physics_sim_vel(position, pi, sim_time, orient);
755 physics_sim_rot(orient, pi, sim_time);
757 pi->speed = vm_vec_mag(&pi->vel); // Note, cannot use quick version, causes cumulative error, increasing speed.
758 pi->fspeed = vm_vec_dot(&orient->fvec, &pi->vel); // instead of vector magnitude -- use only forward vector since we are only interested in forward velocity
763 // -----------------------------------------------------------------------------------------------------------
764 // Simulate a physics object for this frame. Used by the editor. The difference between
765 // this function and physics_sim() is that this one uses a heading change to rotate around
766 // the universal Y axis, rather than the local orientation's Y axis. Banking is also ignored.
767 void physics_sim_editor(vector *position, matrix * orient, physics_info * pi, float sim_time )
769 physics_sim_vel(position, pi, sim_time, orient);
770 physics_sim_rot_editor(orient, pi, sim_time);
771 pi->speed = vm_vec_mag_quick(&pi->vel);
772 pi->fspeed = vm_vec_dot(&orient->fvec, &pi->vel); // instead of vector magnitude -- use only forward vector since we are only interested in forward velocity
775 // function to predict an object's position given the delta time and an objects physics info
776 void physics_predict_pos(physics_info *pi, float delta_time, vector *predicted_pos)
778 apply_physics( pi->side_slip_time_const, pi->desired_vel.x, pi->vel.x, delta_time,
779 NULL, &predicted_pos->x );
781 apply_physics( pi->side_slip_time_const, pi->desired_vel.y, pi->vel.y, delta_time,
782 NULL, &predicted_pos->y );
784 apply_physics( pi->side_slip_time_const, pi->desired_vel.z, pi->vel.z, delta_time,
785 NULL, &predicted_pos->z );
788 // function to predict an object's velocity given the parameters
789 void physics_predict_vel(physics_info *pi, float delta_time, vector *predicted_vel)
791 if (pi->flags & PF_CONST_VEL) {
792 predicted_vel = &pi->vel;
794 apply_physics( pi->side_slip_time_const, pi->desired_vel.x, pi->vel.x, delta_time,
795 &predicted_vel->x, NULL );
797 apply_physics( pi->side_slip_time_const, pi->desired_vel.y, pi->vel.y, delta_time,
798 &predicted_vel->y, NULL );
800 apply_physics( pi->side_slip_time_const, pi->desired_vel.z, pi->vel.z, delta_time,
801 &predicted_vel->z, NULL );
805 // function to predict position and velocity of an object
806 void physics_predict_pos_and_vel(physics_info *pi, float delta_time, vector *predicted_vel, vector *predicted_pos)
809 apply_physics( pi->side_slip_time_const, pi->desired_vel.x, pi->vel.x, delta_time,
810 &predicted_vel->x, &predicted_pos->x );
812 apply_physics( pi->side_slip_time_const, pi->desired_vel.y, pi->vel.y, delta_time,
813 &predicted_vel->y, &predicted_pos->y );
815 apply_physics( pi->side_slip_time_const, pi->desired_vel.z, pi->vel.z, delta_time,
816 &predicted_vel->z, &predicted_pos->z );
819 // physics_read_flying_controls()
821 // parmeters: *orient ==>
824 // Adam: Uncomment-out this define to enable banking while turning.
825 #define BANK_WHEN_TURN
829 // function looks at the flying controls and the current velocity to determine a goal velocity
830 // function determines velocity in object's reference frame and goal velocity in object's reference frame
831 void physics_read_flying_controls( matrix * orient, physics_info * pi, control_info * ci, float sim_time, vector *wash_rot)
833 vector goal_vel; // goal velocity in local coords, *not* accounting for ramping of velcity
834 float ramp_time_const; // time constant for velocity ramping
836 float velocity_ramp (float v_in, float v_goal, float time_const, float t);
838 // if ( keyd_pressed[KEY_LSHIFT] ) {
839 // keyd_pressed[KEY_LSHIFT] = 0;
843 ci->forward += (ci->forward_cruise_percent / 100.0f);
845 // mprintf(("ci->forward == %7.3f\n", ci->forward));
847 // give control imput to cause rotation in engine wash
849 if ( wash_rot && Wash_on ) {
850 ci->pitch += wash_rot->x;
851 ci->bank += wash_rot->z;
852 ci->heading += wash_rot->y;
855 if (ci->pitch > 1.0f ) ci->pitch = 1.0f;
856 else if (ci->pitch < -1.0f ) ci->pitch = -1.0f;
858 if (ci->vertical > 1.0f ) ci->vertical = 1.0f;
859 else if (ci->vertical < -1.0f ) ci->vertical = -1.0f;
861 if (ci->heading > 1.0f ) ci->heading = 1.0f;
862 else if (ci->heading < -1.0f ) ci->heading = -1.0f;
864 if (ci->sideways > 1.0f ) ci->sideways = 1.0f;
865 else if (ci->sideways < -1.0f ) ci->sideways = -1.0f;
867 if (ci->bank > 1.0f ) ci->bank = 1.0f;
868 else if (ci->bank < -1.0f ) ci->bank = -1.0f;
870 if ( pi->flags & PF_AFTERBURNER_ON )
873 if (ci->forward > 1.0f ) ci->forward = 1.0f;
874 else if (ci->forward < -1.0f ) ci->forward = -1.0f;
876 pi->desired_rotvel.x = ci->pitch * pi->max_rotvel.x;
877 pi->desired_rotvel.y = ci->heading * pi->max_rotvel.y;
881 #ifdef BANK_WHEN_TURN
882 // To change direction of bank, negate the whole expression.
883 // To increase magnitude of banking, decrease denominator.
884 // Adam: The following statement is all the math for banking while turning.
885 delta_bank = - (ci->heading * pi->max_rotvel.y)/2.0f;
890 pi->desired_rotvel.z = ci->bank * pi->max_rotvel.z + delta_bank;
891 pi->forward_thrust = ci->forward;
893 if ( pi->flags & PF_AFTERBURNER_ON ) {
894 goal_vel.x = ci->sideways*pi->afterburner_max_vel.x;
895 goal_vel.y = ci->vertical*pi->afterburner_max_vel.y;
896 goal_vel.z = ci->forward* pi->afterburner_max_vel.z;
899 goal_vel.x = ci->sideways*pi->max_vel.x;
900 goal_vel.y = ci->vertical*pi->max_vel.y;
901 goal_vel.z = ci->forward* pi->max_vel.z;
904 if ( goal_vel.z < -pi->max_rear_vel )
905 goal_vel.z = -pi->max_rear_vel;
908 if ( pi->flags & PF_ACCELERATES ) {
910 // Determine *resultant* DESIRED VELOCITY (desired_vel) accounting for RAMPING of velocity
911 // Use LOCAL coordinates
912 // if slide_enabled, ramp velocity for x and y, otherwise set goal (0)
913 // always ramp velocity for z
916 // If reduced damp in effect, then adjust ramp_velocity and desired_velocity can not change as fast.
917 // Scale according to reduced_damp_time_expansion.
918 float reduced_damp_ramp_time_expansion;
919 if ( pi->flags & PF_REDUCED_DAMP ) {
920 float reduced_damp_fraction_time_left = timestamp_until( pi->reduced_damp_decay ) / (float) REDUCED_DAMP_TIME;
921 reduced_damp_ramp_time_expansion = 1.0f + (REDUCED_DAMP_FACTOR-1) * reduced_damp_fraction_time_left;
923 reduced_damp_ramp_time_expansion = 1.0f;
926 // 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) )
927 // Int3(); // Get dave A
929 if (pi->flags & PF_SLIDE_ENABLED) {
930 // determine the local velocity
931 // deterimine whether accelerating or decleration toward goal for x
932 if ( goal_vel.x > 0.0f ) {
933 if ( goal_vel.x >= pi->prev_ramp_vel.x )
934 ramp_time_const = pi->slide_accel_time_const;
936 ramp_time_const = pi->slide_decel_time_const;
937 } else { // goal_vel.x <= 0.0
938 if ( goal_vel.x <= pi->prev_ramp_vel.x )
939 ramp_time_const = pi->slide_accel_time_const;
941 ramp_time_const = pi->slide_decel_time_const;
943 // If reduced damp in effect, then adjust ramp_velocity and desired_velocity can not change as fast
944 if ( pi->flags & PF_REDUCED_DAMP ) {
945 ramp_time_const *= reduced_damp_ramp_time_expansion;
947 pi->prev_ramp_vel.x = velocity_ramp(pi->prev_ramp_vel.x, goal_vel.x, ramp_time_const, sim_time);
949 // deterimine whether accelerating or decleration toward goal for y
950 if ( goal_vel.y > 0.0f ) {
951 if ( goal_vel.y >= pi->prev_ramp_vel.y )
952 ramp_time_const = pi->slide_accel_time_const;
954 ramp_time_const = pi->slide_decel_time_const;
955 } else { // goal_vel.y <= 0.0
956 if ( goal_vel.y <= pi->prev_ramp_vel.y )
957 ramp_time_const = pi->slide_accel_time_const;
959 ramp_time_const = pi->slide_decel_time_const;
961 // If reduced damp in effect, then adjust ramp_velocity and desired_velocity can not change as fast
962 if ( pi->flags & PF_REDUCED_DAMP ) {
963 ramp_time_const *= reduced_damp_ramp_time_expansion;
965 pi->prev_ramp_vel.y = velocity_ramp( pi->prev_ramp_vel.y, goal_vel.y, ramp_time_const, sim_time);
968 pi->prev_ramp_vel.x = 0.0f;
969 pi->prev_ramp_vel.y = 0.0f;
972 // find ramp velocity in the forward direction
973 if ( goal_vel.z >= pi->prev_ramp_vel.z ) {
974 if ( pi->flags & PF_AFTERBURNER_ON )
975 ramp_time_const = pi->afterburner_forward_accel_time_const;
977 ramp_time_const = pi->forward_accel_time_const;
979 ramp_time_const = pi->forward_decel_time_const;
981 // If reduced damp in effect, then adjust ramp_velocity and desired_velocity can not change as fast
982 if ( pi->flags & PF_REDUCED_DAMP ) {
983 ramp_time_const *= reduced_damp_ramp_time_expansion;
985 pi->prev_ramp_vel.z = velocity_ramp( pi->prev_ramp_vel.z, goal_vel.z, ramp_time_const, sim_time);
988 // this translates local desired velocities to world velocities
990 vm_vec_zero(&pi->desired_vel);
991 vm_vec_scale_add2( &pi->desired_vel, &orient->rvec, pi->prev_ramp_vel.x );
992 vm_vec_scale_add2( &pi->desired_vel, &orient->uvec, pi->prev_ramp_vel.y );
993 vm_vec_scale_add2( &pi->desired_vel, &orient->fvec, pi->prev_ramp_vel.z );
994 } else // object does not accelerate (PF_ACCELERATES not set)
995 pi->desired_vel = pi->vel;
1000 // ----------------------------------------------------------------
1001 // Do *dest = *delta unless:
1002 // *delta is pretty small
1003 // and they are of different signs.
1004 void physics_set_rotvel_and_saturate(float *dest, float delta)
1007 if ((delta ^ *dest) < 0) {
1008 if (abs(delta) < F1_0/8) {
1009 // mprintf((0, "D"));
1012 // mprintf((0, "d"));
1015 // mprintf((0, "!"));
1023 // ----------------------------------------------------------------------------
1024 // physics_apply_whack applies an instaneous whack on an object changing
1025 // both the objects velocity and the rotational velocity based on the impulse
1028 // input: impulse => impulse vector ( force*time = impulse = change in momentum (mv) )
1029 // pos => vector from center of mass to location of where the force acts
1030 // pi => pointer to phys_info struct of object getting whacked
1031 // orient => orientation matrix (needed to set rotational impulse in body coords)
1032 // mass => mass of the object (may be different from pi.mass if docked)
1034 #define WHACK_LIMIT 0.001f
1035 #define ROTVEL_WHACK_CONST 0.12
1036 void physics_apply_whack(vector *impulse, vector *pos, physics_info *pi, matrix *orient, float mass)
1038 vector local_torque, torque;
1041 // Detect null vector.
1042 if ((fl_abs(impulse->x) <= WHACK_LIMIT) && (fl_abs(impulse->y) <= WHACK_LIMIT) && (fl_abs(impulse->z) <= WHACK_LIMIT))
1045 // first do the rotational velocity
1046 // calculate the torque on the body based on the point on the
1047 // object that was hit and the momentum being applied to the object
1049 vm_vec_crossprod(&torque, pos, impulse);
1050 vm_vec_rotate ( &local_torque, &torque, orient );
1052 vector delta_rotvel;
1053 vm_vec_rotate( &delta_rotvel, &local_torque, &pi->I_body_inv );
1054 vm_vec_scale ( &delta_rotvel, (float) ROTVEL_WHACK_CONST );
1055 vm_vec_add2( &pi->rotvel, &delta_rotvel );
1058 if (check_rotvel_limit( pi )) {
1059 nprintf(("Physics", "rotvel reset in physics_apply_whack\n"));
1063 //mprintf(("Whack: %7.3f %7.3f %7.3f\n", pi->rotvel.x, pi->rotvel.y, pi->rotvel.z));
1065 // instant whack on the velocity
1066 // reduce damping on all axes
1067 pi->flags |= PF_REDUCED_DAMP;
1068 update_reduced_damp_timestamp( pi, vm_vec_mag(impulse) );
1070 // find time for shake from weapon to end
1071 int dtime = timestamp_until(pi->afterburner_decay);
1072 if (dtime < WEAPON_SHAKE_TIME) {
1073 pi->afterburner_decay = timestamp( WEAPON_SHAKE_TIME );
1076 vm_vec_scale_add2( &pi->vel, impulse, 1.0f / pi->mass );
1077 if (!(pi->flags & PF_USE_VEL) && (vm_vec_mag_squared(&pi->vel) > MAX_SHIP_SPEED*MAX_SHIP_SPEED)) {
1079 nprintf(("Physics", "speed reset in physics_apply_whack [speed: %f]\n", vm_vec_mag(&pi->vel)));
1081 vm_vec_normalize(&pi->vel);
1082 vm_vec_scale(&pi->vel, (float)RESET_SHIP_SPEED);
1084 vm_vec_rotate( &pi->prev_ramp_vel, &pi->vel, orient ); // set so velocity will ramp starting from current speed
1085 // ramped velocity is now affected by collision
1088 // function generates a velocity ramp with a given time constant independent of frame rate
1089 // uses an exponential approach to desired velocity and a cheat when close to improve closure speed
1090 float velocity_ramp (float v_in, float v_goal, float ramp_time_const, float t)
1096 // JAS: If no time elapsed, change nothing
1100 delta_v = v_goal - v_in;
1101 dist = (float)fl_abs(delta_v);
1103 // hack to speed up closure when close to goal
1104 if (dist < ramp_time_const/3)
1105 ramp_time_const = dist / 3;
1107 // Rather than get a divide by zero, just go to the goal
1108 if ( ramp_time_const < 0.0001f ) {
1112 // determine decay factor (ranges from 0 for short times to 1 for long times)
1113 // when decay factor is near 0, the velocity in nearly unchanged
1114 // when decay factor in near 1, the velocity approaches goal
1115 decay_factor = (float)exp(- t / ramp_time_const);
1117 return (v_in + delta_v * (1.0f - decay_factor) );
1121 // ----------------------------------------------------------------------------
1122 // physics_apply_shock applies applies a shockwave to an object. This causes a velocity impulse and
1123 // and a rotational impulse. This is different than physics_apply_whack since a shock wave is a pressure
1124 // wave which acts over the *surface* of the object, not a point.
1126 // inputs: direction_vec => a position vector whose direction is from the center of the shock wave to the object
1127 // pressure => the pressure of the shock wave at the object
1128 // pi => physics_info structure
1129 // orient => matrix orientation of the object
1130 // min => vector of minimum values of the bounding box
1131 // max => vector of maximum values of the bounding box
1132 // radius => bounding box radius of the object, used for scaling rotation
1134 // outputs: makes changes to physics_info structure rotvel and vel variables
1136 #define STD_PRESSURE 1000 // amplitude of standard shockwave blasts
1137 #define MIN_RADIUS 10 // radius within which full rotvel and shake applied
1138 #define MAX_RADIUS 50 // radius at which no rotvel or shake applied
1139 #define MAX_ROTVEL 0.4 // max rotational velocity
1140 #define MAX_SHAKE 0.1 // max rotational amplitude of shake
1141 #define MAX_VEL 8 // max vel from shockwave
1142 void physics_apply_shock(vector *direction_vec, float pressure, physics_info *pi, matrix *orient, vector *min, vector *max, float radius)
1145 vector local_torque, temp_torque, torque;
1150 if (radius > MAX_RADIUS) {
1154 vm_vec_normalize_safe ( direction_vec );
1156 area.x = (max->y - min->z) * (max->z - min->z);
1157 area.y = (max->x - min->x) * (max->z - min->z);
1158 area.z = (max->x - min->x) * (max->y - min->y);
1160 normal.x = vm_vec_dotprod( direction_vec, &orient->rvec );
1161 normal.y = vm_vec_dotprod( direction_vec, &orient->uvec );
1162 normal.z = vm_vec_dotprod( direction_vec, &orient->fvec );
1164 sin.x = fl_sqrt( fl_abs(1.0f - normal.x*normal.x) );
1165 sin.y = fl_sqrt( fl_abs(1.0f - normal.y*normal.y) );
1166 sin.z = fl_sqrt( fl_abs(1.0f - normal.z*normal.z) );
1168 vm_vec_make( &torque, 0.0f, 0.0f, 0.0f );
1170 // find the torque exerted due to the shockwave hitting each face
1171 // model the effect of the shockwave as if the shockwave were a plane of projectiles,
1172 // all moving in the direction direction_vec. then find the torque as the cross prod
1173 // of the force (pressure * area * normal * sin * scale * mass)
1174 // normal takes account the fraction of the surface exposed to the shockwave
1175 // the sin term is not technically needed but "feels" better
1176 // scale factors out the increase in area with larger objects
1177 // more massive objects get less rotation
1179 // find torque due to forces on the right/left face
1180 if ( normal.x < 0.0f ) // normal < 0, hits the right face
1181 vm_vec_copy_scale( &impact_vec, &orient->rvec, max->x * pressure * area.x * normal.x * sin.x / pi->mass );
1182 else // normal > 0, hits the left face
1183 vm_vec_copy_scale( &impact_vec, &orient->rvec, min->x * pressure * area.x * -normal.x * sin.x / pi->mass );
1185 vm_vec_crossprod( &temp_torque, &impact_vec, direction_vec );
1186 vm_vec_add2( &torque, &temp_torque );
1188 // find torque due to forces on the up/down face
1189 if ( normal.y < 0.0f )
1190 vm_vec_copy_scale( &impact_vec, &orient->uvec, max->y * pressure * area.y * normal.y * sin.y / pi->mass );
1192 vm_vec_copy_scale( &impact_vec, &orient->uvec, min->y * pressure * area.y * -normal.y * sin.y / pi->mass );
1194 vm_vec_crossprod( &temp_torque, &impact_vec, direction_vec );
1195 vm_vec_add2( &torque, &temp_torque );
1197 // find torque due to forces on the forward/backward face
1198 if ( normal.z < 0.0f )
1199 vm_vec_copy_scale( &impact_vec, &orient->fvec, max->z * pressure * area.z * normal.z * sin.z / pi->mass );
1201 vm_vec_copy_scale( &impact_vec, &orient->fvec, min->z * pressure * area.z * -normal.z * sin.z / pi->mass );
1203 vm_vec_crossprod( &temp_torque, &impact_vec, direction_vec );
1204 vm_vec_add2( &torque, &temp_torque );
1206 // compute delta rotvel, scale according to blast and radius
1208 vector delta_rotvel;
1209 vm_vec_rotate( &local_torque, &torque, orient );
1210 vm_vec_copy_normalize(&delta_rotvel, &local_torque);
1211 if (radius < MIN_RADIUS) {
1214 scale = (MAX_RADIUS - radius)/(MAX_RADIUS-MIN_RADIUS);
1216 vm_vec_scale(&delta_rotvel, (float)(MAX_ROTVEL*(pressure/STD_PRESSURE)*scale));
1217 // nprintf(("Physics", "rotvel scale %f\n", (MAX_ROTVEL*(pressure/STD_PRESSURE)*scale)));
1218 vm_vec_add2(&pi->rotvel, &delta_rotvel);
1220 // set shockwave shake amplitude, duration, flag
1221 pi->shockwave_shake_amp = (float)(MAX_SHAKE*(pressure/STD_PRESSURE)*scale);
1222 pi->shockwave_decay = timestamp( SW_BLAST_DURATION );
1223 pi->flags |= PF_IN_SHOCKWAVE;
1225 // set reduced translational damping, set flags
1226 float velocity_scale = (float)MAX_VEL*scale;
1227 pi->flags |= PF_REDUCED_DAMP;
1228 update_reduced_damp_timestamp( pi, velocity_scale*pi->mass );
1229 vm_vec_scale_add2( &pi->vel, direction_vec, velocity_scale );
1230 vm_vec_rotate(&pi->prev_ramp_vel, &pi->vel, orient); // set so velocity will ramp starting from current speed
1232 // check that kick from shockwave is not too large
1233 if (!(pi->flags & PF_USE_VEL) && (vm_vec_mag_squared(&pi->vel) > MAX_SHIP_SPEED*MAX_SHIP_SPEED)) {
1235 nprintf(("Physics", "speed reset in physics_apply_shock [speed: %f]\n", vm_vec_mag(&pi->vel)));
1237 vm_vec_normalize(&pi->vel);
1238 vm_vec_scale(&pi->vel, (float)RESET_SHIP_SPEED);
1242 if (check_rotvel_limit( pi )) {
1243 nprintf(("Physics", "rotvel reset in physics_apply_shock\n"));
1247 // ramped velocity is now affected by collision
1250 // ----------------------------------------------------------------------------
1251 // physics_collide_whack applies an instaneous whack on an object changing
1252 // both the objects velocity and the rotational velocity based on the impulse
1255 // input: impulse => impulse vector ( force*time = impulse = change in momentum (mv) )
1256 // world_delta_rotvel => change in rotational velocity (already calculated)
1257 // pi => pointer to phys_info struct of object getting whacked
1258 // orient => orientation matrix (needed to set rotational impulse in body coords)
1261 // Warning: Do not change ROTVEL_COLLIDE_WHACK_CONST. This will mess up collision physics.
1262 // If you need to change the rotation, change COLLISION_ROTATION_FACTOR in collide_ship_ship.
1263 #define ROTVEL_COLLIDE_WHACK_CONST 1.0
1264 void physics_collide_whack( vector *impulse, vector *world_delta_rotvel, physics_info *pi, matrix *orient )
1266 vector body_delta_rotvel;
1268 // Detect null vector.
1269 if ((fl_abs(impulse->x) <= WHACK_LIMIT) && (fl_abs(impulse->y) <= WHACK_LIMIT) && (fl_abs(impulse->z) <= WHACK_LIMIT))
1272 vm_vec_rotate( &body_delta_rotvel, world_delta_rotvel, orient );
1273 // vm_vec_scale( &body_delta_rotvel, (float) ROTVEL_COLLIDE_WHACK_CONST );
1274 vm_vec_add2( &pi->rotvel, &body_delta_rotvel );
1277 if (check_rotvel_limit( pi )) {
1278 nprintf(("Physics", "rotvel reset in physics_collide_whack\n"));
1282 update_reduced_damp_timestamp( pi, vm_vec_mag(impulse) );
1284 // find time for shake from weapon to end
1285 int dtime = timestamp_until(pi->afterburner_decay);
1286 if (dtime < WEAPON_SHAKE_TIME) {
1287 pi->afterburner_decay = timestamp( WEAPON_SHAKE_TIME );
1290 pi->flags |= PF_REDUCED_DAMP;
1291 vm_vec_scale_add2( &pi->vel, impulse, 1.0f / pi->mass );
1292 // check that collision does not give ship too much speed
1293 // reset if too high
1294 if (!(pi->flags & PF_USE_VEL) && (vm_vec_mag_squared(&pi->vel) > MAX_SHIP_SPEED*MAX_SHIP_SPEED)) {
1296 nprintf(("Physics", "speed reset in physics_collide_whack [speed: %f]\n", vm_vec_mag(&pi->vel)));
1298 vm_vec_normalize(&pi->vel);
1299 vm_vec_scale(&pi->vel, (float)RESET_SHIP_SPEED);
1301 vm_vec_rotate( &pi->prev_ramp_vel, &pi->vel, orient ); // set so velocity will ramp starting from current speed
1302 // ramped velocity is now affected by collision
1303 // rotate previous ramp velocity (in model coord) to be same as vel (in world coords)
1307 int check_rotvel_limit( physics_info *pi )
1309 if ( 0 == pi->flags ) // weapon
1315 int change_made = 0;
1316 if ( !(pi->flags & PF_DEAD_DAMP) ) {
1317 // case of normal, live ship
1318 // -- Commented out by MK: Assert( vm_vec_mag_squared(&pi->max_rotvel) > ROTVEL_TOL );
1319 // Assert( (pi->max_rotvel.x <= ROTVEL_CAP) && (pi->max_rotvel.y <= ROTVEL_CAP) && (pi->max_rotvel.z <= ROTVEL_CAP) );
1320 // Warning(LOCATION,"Excessive rotvel (wx: %f, wy: %f, wz:%f)\n", pi->rotvel.x, pi->rotvel.y, pi->rotvel.z);
1321 if ( fl_abs(pi->rotvel.x) > pi->max_rotvel.x ) {
1322 pi->rotvel.x = (pi->rotvel.x / fl_abs(pi->rotvel.x)) * (pi->max_rotvel.x - (float) ROTVEL_TOL);
1325 if ( fl_abs(pi->rotvel.y) > pi->max_rotvel.y ) {
1326 pi->rotvel.y = (pi->rotvel.y / fl_abs(pi->rotvel.y)) * (pi->max_rotvel.y - (float) ROTVEL_TOL);
1329 if ( fl_abs(pi->rotvel.z) > pi->max_rotvel.z ) {
1330 pi->rotvel.z = (pi->rotvel.z / fl_abs(pi->rotvel.z)) * (pi->max_rotvel.z - (float) ROTVEL_TOL);
1334 // case of dead ship
1335 if ( fl_abs(pi->rotvel.x) > DEAD_ROTVEL_CAP ) {
1336 pi->rotvel.x = (pi->rotvel.x / fl_abs(pi->rotvel.x)) * (float) (DEAD_ROTVEL_CAP - ROTVEL_TOL);
1339 if ( fl_abs(pi->rotvel.y) > DEAD_ROTVEL_CAP ) {
1340 pi->rotvel.y = (pi->rotvel.y / fl_abs(pi->rotvel.y)) * (float) (DEAD_ROTVEL_CAP - ROTVEL_TOL);
1343 if ( fl_abs(pi->rotvel.z) > DEAD_ROTVEL_CAP ) {
1344 pi->rotvel.z = (pi->rotvel.z / fl_abs(pi->rotvel.z)) * (float) (DEAD_ROTVEL_CAP - ROTVEL_TOL);
1351 // ----------------------------------------------------------------------------
1352 // update_reduced_damp_timestamp()
1354 void update_reduced_damp_timestamp( physics_info *pi, float impulse )
1357 // Compute duration of reduced damp from present
1358 // Compare with current value and increase if greater, otherwise ignore
1359 int reduced_damp_decay_time;
1360 reduced_damp_decay_time = (int) (REDUCED_DAMP_TIME * impulse / (REDUCED_DAMP_VEL * pi->mass));
1361 if ( reduced_damp_decay_time > REDUCED_DAMP_TIME )
1362 reduced_damp_decay_time = REDUCED_DAMP_TIME;
1364 // Reset timestamp if larger than current (if any)
1365 if ( timestamp_valid( pi->reduced_damp_decay ) ) {
1366 int time_left = timestamp_until( pi->reduced_damp_decay );
1367 if ( time_left > 0 ) {
1368 // increment old time, but apply cap
1369 int new_time = reduced_damp_decay_time + time_left;
1370 if ( new_time < REDUCED_DAMP_TIME ) {
1371 pi->reduced_damp_decay = timestamp( new_time );
1374 pi->reduced_damp_decay = timestamp( reduced_damp_decay_time );
1378 pi->reduced_damp_decay = timestamp( reduced_damp_decay_time );