ryan's struct patch for gcc 2.95

[taylor/freespace2.git] / src / debris / debris.cpp

/*
 * Copyright (C) Volition, Inc. 1999.  All rights reserved.
 *
 * All source code herein is the property of Volition, Inc. You may not sell 
 * or otherwise commercially exploit the source or things you created based on
 * the source.
 */

/*
 * $Logfile: /Freespace2/code/Debris/Debris.cpp $
 * $Revision$
 * $Date$
 * $Author$
 *
 * Code for the pieces of exploding object debris.
 *
 * $Log$
 * Revision 1.4  2002/06/17 06:33:08  relnev
 * ryan's struct patch for gcc 2.95
 *
 * Revision 1.3  2002/06/09 04:41:15  relnev
 * added copyright header
 *
 * Revision 1.2  2002/05/28 08:52:03  relnev
 * implemented two assembly stubs.
 *
 * cleaned up a few warnings.
 *
 * added a little demo hackery to make it progress a little farther.
 *
 * Revision 1.1.1.1  2002/05/03 03:28:08  root
 * Initial import.
 *
 * 
 * 16    8/01/99 1:13p Dave
 * Fixed objsnd problem with hull debris pieces.
 * 
 * 15    7/01/99 4:23p Dave
 * Full support for multiple linked ambient engine sounds. Added "big
 * damage" flag.
 * 
 * 14    7/01/99 11:44a Dave
 * Updated object sound system to allow multiple obj sounds per ship.
 * Added hit-by-beam sound. Added killed by beam sound.
 * 
 * 13    5/18/99 11:50a Andsager
 * Remove unused object type OBJ_GHOST_SAVE
 * 
 * 12    5/14/99 11:50a Andsager
 * Added vaporize for SMALL ships hit by HUGE beams.  Modified dying
 * frame.  Enlarged debris shards and range at which visible.
 * 
 * 11    4/23/99 12:01p Johnson
 * Added SIF_HUGE_SHIP
 * 
 * 10    2/26/99 4:14p Dave
 * Put in the ability to have multiple shockwaves for ships.
 * 
 * 9     1/20/99 6:04p Dave
 * Another bit of stuff for beam weapons. Ships will properly use them
 * now, although they're really deadly.
 * 
 * 8     12/03/98 3:14p Andsager
 * Check in code that checks rotating submodel actually has ship subsystem
 * 
 * 7     11/19/98 11:07p Andsager
 * Check in of physics and collision detection of rotating submodels
 * 
 * 6     11/13/98 10:13a Andsager
 * simplify collision code
 * 
 * 5     11/05/98 5:55p Dave
 * Big pass at reducing #includes
 * 
 * 4     10/23/98 1:11p Andsager
 * Make ship sparks emit correctly from rotating structures.
 * 
 * 3     10/16/98 1:22p Andsager
 * clean up header files
 * 
 * 2     10/07/98 10:52a Dave
 * Initial checkin.
 * 
 * 1     10/07/98 10:48a Dave
 * 
 * 119   8/28/98 3:28p Dave
 * EMP effect done. AI effects may need some tweaking as required.
 * 
 * 118   5/03/98 5:41p Mike
 * Add Framecount to nprintf.
 * 
 * 117   4/15/98 10:00p Allender
 * make debris have own signature set.
 * 
 * 116   4/15/98 9:42a Adam
 * added 2 more explosion types (1, actually, but placeholder for 2)
 * 
 * 115   4/13/98 4:52p Allender
 * remove AI_frametime and us flFrametime instead.  Make lock warning work
 * in multiplayer for aspect seeking missiles.  Debris fixups
 * 
 * 114   4/10/98 12:16p Allender
 * fix ship hit kill and debris packets
 * 
 * 113   4/09/98 5:43p Allender
 * multiplayer network object fixes.  debris and self destructed ships
 * should all sync up.  Fix problem where debris pieces (hull pieces) were
 * not getting a net signature
 * 
 * 112   4/01/98 5:34p John
 * Made only the used POFs page in for a level.   Reduced some interp
 * arrays.    Made custom detail level work differently.
 * 
 * 111   3/31/98 5:11p John
 * Removed demo/save/restore.  Made NDEBUG defined compile.  Removed a
 * bunch of debug stuff out of player file.  Made model code be able to
 * unload models and malloc out only however many models are needed.
 * 
 * 110   3/26/98 5:21p John
 * Added new code to preload all bitmaps at the start of a level.
 * Commented it out, though.
 * 
 * 109   3/23/98 12:20p Andsager
 * Enable collision from rotation in ship_debris and ship_debris
 * collisions.
 * 
 * 108   3/19/98 12:09p John
 * Fixed a bug using 6 characters.   r_heavy was using local coordinates
 * instead of world so all asteroid-ship and debris-ship hitpos's were in
 * the wrong spot.  Ok, I rearreanged some code to make it clearer also.
 * 
 * 
 * 107   3/12/98 6:47p John
 * MAde arcs on debris further than objrad*50 not render.
 * 
 * 106   3/09/98 2:10p Andsager
 * Put in checks for debris (other) with excessive velocity.
 * 
 * 105   2/26/98 10:07p Hoffoss
 * Rewrote state saving and restoring to fix bugs and simplify the code.
 * 
 * 104   2/22/98 12:19p John
 * Externalized some strings
 * 
 * 103   2/20/98 8:31p Lawrance
 * Add radius parm to sound_play_3d()
 * 
 * 102   2/10/98 6:43p Lawrance
 * Moved asteroid code to a separate lib.
 * 
 * 101   2/07/98 2:14p Mike
 * Improve asteroid splitting.  Add ship:asteroid collisions.  Timestamp
 * ship:debris collisions.
 * 
 * 100   2/06/98 7:45p John
 * Reversed order of asteroid models so blown up ones are smaller.  
 * 
 * 99    2/06/98 7:28p John
 * Made debris and particles not get created if > 200 m from eye.   Added
 * max_velocity to asteroid's physics info for aiding in throwing out
 * collision pairs.
 * 
 * 98    2/06/98 3:08p Mike
 * More asteroid stuff, including resolving conflicts between the two
 * asteroid_field structs!
 * 
 * 97    2/06/98 12:25a Mike
 * More asteroid stuff.
 * 
 * 96    2/05/98 9:41p Mike
 * Asteroid work, intermediate checkin to resolve compile errors.
 * 
 * 95    2/05/98 9:21p John
 * Some new Direct3D code.   Added code to monitor a ton of stuff in the
 * game.
 * 
 * 94    2/05/98 12:51a Mike
 * Early asteroid stuff.
 * 
 * 93    2/03/98 6:01p Andsager
 * Fix excessive rotvel in debris_create.  Check using physics function
 * check_rotvel_limit.
 * 
 * 92    2/03/98 11:14a Andsager
 * Temp check in to stop debris being created with excess rotvel
 * 
 * 91    2/02/98 4:45p Mike
 * Increase translational and rotational velocity imparted to debris
 * pieces at request of Adam.
 * 
 * 90    1/30/98 2:56p John
 * Made debris arcs jump around.  Made only 2/3 of the chunks have arcing
 * 
 * 89    1/30/98 11:48a John
 * Made debris arcs cast light.  Added sound effects for them.
 * 
 * 88    1/29/98 5:50p John
 * Made electrical arcing on debris pieces be persistent from frame to
 * frame
 * 
 * 87    1/29/98 8:39a Andsager
 * Changed mass and moment of intertia based area vs. volume
 * 
 * 86    1/27/98 11:02a John
 * Added first rev of sparks.   Made all code that calls model_render call
 * clear_instance first.   Made debris pieces not render by default when
 * clear_instance is called.
 * 
 * 85    1/24/98 4:49p Lawrance
 * Only delete hull piece if you can find an old one that isn't already
 * about to die.
 * 
 * 84    1/23/98 5:06p John
 * Took L out of vertex structure used B (blue) instead.   Took all small
 * fireballs out of fireball types and used particles instead.  Fixed some
 * debris explosion things.  Restructured fireball code.   Restructured
 * some lighting code.   Made dynamic lighting on by default. Made groups
 * of lasers only cast one light.  Made fireballs not cast light.
 * 
 * $NoKeywords: $
 */

#include "3d.h"
#include "bmpman.h"
#include "object.h"
#include "debris.h"
#include "fireballs.h"
#include "radar.h"
#include "missionparse.h"               // For MAX_SPECIES_NAMES
#include "gamesnd.h"
#include "objectsnd.h"
#include "linklist.h"
#include "systemvars.h"
#include "multi.h"
#include "multimsgs.h"
#include "particle.h"
#include "freespace.h"
#include "multiutil.h"
#include "objcollide.h"
#include "timer.h"

#define MAX_LIFE                                                                        10.0f
#define MIN_RADIUS_FOR_PERSISTANT_DEBRIS        50              // ship radius at which debris from it becomes persistant
#define DEBRIS_SOUND_DELAY                                              2000    // time to start debris sound after created

// limit the number of hull debris chunks that can exist.  
#define MAX_HULL_PIECES         10
int             Num_hull_pieces;                // number of hull pieces in existance
debris  Hull_debris_list;               // head of linked list for hull debris chunks, for quick search

debris Debris[MAX_DEBRIS_PIECES];

int Num_debris_pieces = 0;
int Debris_inited = 0;

int Debris_model = -1;
int Debris_vaporize_model = -1;
int Debris_num_submodels = 0;
char * Debris_texture_files[MAX_SPECIES_NAMES] = { 
        NOX("debris01a"),       // Terran
        NOX("debris01b"),       // Species B
        NOX("debris01c"),       // Shivan
        };

int Debris_textures[MAX_SPECIES_NAMES];

#define MAX_DEBRIS_DIST                                 10000.0f                        //      Debris goes away if it's this far away.
#define DEBRIS_DISTANCE_CHECK_TIME              (10*1000)               //      Check every 10 seconds.
#define DEBRIS_INDEX(dp) (dp-Debris)

#define MAX_SPEED_SMALL_DEBRIS          200                                     // maximum velocity of small debris piece
#define MAX_SPEED_BIG_DEBRIS                    150                                     // maximum velocity of big debris piece
#define MAX_SPEED_CAPITAL_DEBRIS        100                                     // maximum velocity of capital debris piece
#define DEBRIS_SPEED_DEBUG

// ---------------------------------------------------------------------------------------
// debris_start_death_roll()
//
//      Start the sequence of a piece of debris writhing in unholy agony!!!
//
static void debris_start_death_roll(object *debris_obj, debris *debris_p)
{
        if (debris_p->is_hull)  {
                // tell everyone else to blow up the piece of debris
                if( MULTIPLAYER_MASTER )
                        send_debris_update_packet(debris_obj,DEBRIS_UPDATE_NUKE);

                int fireball_type = FIREBALL_EXPLOSION_LARGE1 + rand()%FIREBALL_NUM_LARGE_EXPLOSIONS;
                fireball_create( &debris_obj->pos, fireball_type, OBJ_INDEX(debris_obj), debris_obj->radius*1.75f);

                // only play debris destroy sound if hull piece and it has been around for at least 2 seconds
                if ( Missiontime > debris_p->time_started + 2*F1_0 ) {
                        snd_play_3d( &Snds[SND_MISSILE_IMPACT1], &debris_obj->pos, &View_position, debris_obj->radius );
                        
                }
        }

        debris_obj->flags |= OF_SHOULD_BE_DEAD;
//      demo_do_flag_dead(OBJ_INDEX(debris_obj));
}

// ---------------------------------------------------------------------------------------
// debris_init()
//
// This will get called at the start of each level.
//
void debris_init()
{
        int i;

        if ( !Debris_inited ) {
                Debris_inited = 1;
        }

        Debris_model = -1;
        Debris_vaporize_model = -1;
        Debris_num_submodels = 0;
                
        // Reset everything between levels
        Num_debris_pieces = 0;
        for (i=0; i<MAX_DEBRIS_PIECES; i++ )    {
                Debris[i].flags = 0;
                Debris[i].sound_delay = 0;
        }
                
        Num_hull_pieces = 0;
        list_init(&Hull_debris_list);
}

// Page in debris bitmaps at level load
void debris_page_in()
{
        int i;

        Debris_model = model_load( NOX("debris01.pof"), 0, NULL );
        if (Debris_model>-1)    {
                polymodel * pm;
                pm = model_get(Debris_model);
                Debris_num_submodels = pm->n_models;
        }

        Debris_vaporize_model = model_load( NOX("debris02.pof"), 0, NULL );

        for (i=0; i<MAX_SPECIES_NAMES; i++ )    {
                nprintf(( "Paging", "Paging in debris texture '%s'\n", Debris_texture_files[i] ));
                Debris_textures[i] = bm_load( Debris_texture_files[i] );
                if ( Debris_textures[i] < 0 ) { 
                        Warning( LOCATION, "Couldn't load species %d debris\ntexture, '%s'\n", i, Debris_texture_files[i] );
                }
                bm_page_in_texture( Debris_textures[i] );
        }
        
}

MONITOR(NumSmallDebrisRend);
MONITOR(NumHullDebrisRend);

// ---------------------------------------------------------------------------------------
// debris_render()
//
//
void debris_render(object * obj)
{
        int                     i, num, swapped;
        polymodel       *pm;
        debris          *db;


        swapped = -1;
        pm = NULL;      
        num = obj->instance;

        Assert(num >= 0 && num < MAX_DEBRIS_PIECES );
        db = &Debris[num];

        Assert( db->flags & DEBRIS_USED );

        // Swap in a different texture depending on the species
        if ( (db->species > -1) && (db->species < MAX_SPECIES_NAMES) )  {

                pm = model_get( db->model_num );

                if ( pm && (pm->n_textures == 1) ) {
                        swapped = pm->textures[0];
                        pm->textures[0] = Debris_textures[db->species];
                }
        }

        model_clear_instance( db->model_num );

        // Only render electrical arcs if within 500m of the eye (for a 10m piece)
        if ( vm_vec_dist_quick( &obj->pos, &Eye_position ) < obj->radius*50.0f )        {
                for (i=0; i<MAX_DEBRIS_ARCS; i++ )      {
                        if ( timestamp_valid( db->arc_timestamp[i] ) )  {
                                model_add_arc( db->model_num, db->submodel_num, &db->arc_pts[i][0], &db->arc_pts[i][1], MARC_TYPE_NORMAL );
                        }
                }
        }

        if ( db->is_hull )      {
                MONITOR_INC(NumHullDebrisRend,1);
                submodel_render( db->model_num, db->submodel_num, &obj->orient, &obj->pos );
        } else {
                MONITOR_INC(NumSmallDebrisRend,1);
                submodel_render( db->model_num, db->submodel_num, &obj->orient, &obj->pos, MR_NO_LIGHTING );
        }

        if ((swapped!=-1) && pm)        {
                pm->textures[0] = swapped;
        }
}

// Removed the DEBRIS_EXPIRE flag, and remove item from Hull_debris_list
void debris_clear_expired_flag(debris *db)
{
        if ( db->flags & DEBRIS_EXPIRE ) {
                db->flags &= ~DEBRIS_EXPIRE;
                if ( db->is_hull ) {
                        Num_hull_pieces--;
                        list_remove(Hull_debris_list, db);
                        Assert( Num_hull_pieces >= 0 );
                }
        }
}

// ---------------------------------------------------------------------------------------
// debris_delete()
//
// Delete the debris object.  This is only ever called via obj_delete().  Do not call directly.
// Use debris_start_death_roll() if you want to force a debris piece to die.
//
void debris_delete( object * obj )
{
        int             num;
        debris  *db;

        num = obj->instance;
        Assert( Debris[num].objnum == OBJ_INDEX(obj));

        db = &Debris[num];

        Assert( Num_debris_pieces >= 0 );
        if ( db->is_hull && (db->flags & DEBRIS_EXPIRE) ) {
                debris_clear_expired_flag(db);
        }

        db->flags = 0;
        Num_debris_pieces--;
}

//      If debris piece *db is far away from all players, make it go away very soon.
//      In single player game, delete if MAX_DEBRIS_DIST from player.
//      In multiplayer game, delete if MAX_DEBRIS_DIST from all players.
void maybe_delete_debris(debris *db)
{
        object  *objp;

        if (timestamp_elapsed(db->next_distance_check)) {
                if (!(Game_mode & GM_MULTIPLAYER)) {            //      In single player game, just check against player.
                        if (vm_vec_dist_quick(&Player_obj->pos, &Objects[db->objnum].pos) > MAX_DEBRIS_DIST)
                                db->lifeleft = 0.1f;
                        else
                                db->next_distance_check = timestamp(DEBRIS_DISTANCE_CHECK_TIME);
                } else {
                        for ( objp = GET_FIRST(&obj_used_list); objp !=END_OF_LIST(&obj_used_list); objp = GET_NEXT(objp) ) {
                                if (objp->flags & OF_PLAYER_SHIP) {
                                        if (vm_vec_dist_quick(&objp->pos, &Objects[db->objnum].pos) < MAX_DEBRIS_DIST) {
                                                db->next_distance_check = timestamp(DEBRIS_DISTANCE_CHECK_TIME);
                                                return;
                                        }
                                }
                        }
                        db->lifeleft = 0.1f;
                }
        }
}

// broke debris_move into debris_process_pre and debris_process_post as was done with all
// *_move functions on 8/13 by MK and MA.
void debris_process_pre( object *objp, float frame_time)
{
}

MONITOR(NumSmallDebris);
MONITOR(NumHullDebris);

// ---------------------------------------------------------------------------------------
// debris_process_post()
//
// Do various updates to debris:  check if time to die, start fireballs
//
// parameters:          obj                     =>              pointer to debris object
//                                              frame_time      =>              time elapsed since last debris_move() called
//
//      Maybe delete debris if it's very far away from player.
void debris_process_post(object * obj, float frame_time)
{
        int i, num;
        num = obj->instance;

        int objnum = OBJ_INDEX(obj);
        Assert( Debris[num].objnum == objnum );
        debris *db = &Debris[num];

        if ( db->is_hull ) {
                MONITOR_INC(NumHullDebris,1);
                radar_plot_object( obj );

                if ( timestamp_elapsed(db->sound_delay) ) {
                        obj_snd_assign(objnum, SND_DEBRIS, &vmd_zero_vector, 0);
                        db->sound_delay = 0;
                }
        } else {
                MONITOR_INC(NumSmallDebris,1);
        }

        if ( db->lifeleft >= 0.0f) {
                db->lifeleft -= frame_time;
                if ( db->lifeleft < 0.0f )      {
                        debris_start_death_roll(obj, db);
                }
        }

        maybe_delete_debris(db);        //      Make this debris go away if it's very far away.

        // ================== DO THE ELECTRIC ARCING STUFF =====================
        if ( db->arc_frequency <= 0 )   {
                return;                 // If arc_frequency <= 0, this piece has no arcs on it
        }

        if ( !timestamp_elapsed(db->fire_timeout) && timestamp_elapsed(db->next_fireball))      {

                // start the next fireball up in the next 50 - 100 ms
                //db->next_fireball = timestamp_rand(60,80);            

                db->next_fireball = timestamp_rand(db->arc_frequency,db->arc_frequency*2 );
                db->arc_frequency += 100;       

                if (db->is_hull)        {

                        int n, n_arcs = ((rand()>>5) % 3)+1;            // Create 1-3 sparks

                        vector v1, v2, v3, v4;
                        submodel_get_two_random_points( db->model_num, db->submodel_num, &v1, &v2 );
                        submodel_get_two_random_points( db->model_num, db->submodel_num, &v3, &v4 );

                        n = 0;

                        int a = 100, b = 1000;
                        int lifetime = (myrand()%((b)-(a)+1))+(a);

                        // Create the spark effects
                        for (i=0; i<MAX_DEBRIS_ARCS; i++ )      {
                                if ( !timestamp_valid( db->arc_timestamp[i] ) ) {
                                        //db->arc_timestamp[i] = timestamp_rand(400,1000);      // live up to a second
                                        db->arc_timestamp[i] = timestamp(lifetime);     // live up to a second

                                        switch( n )     {
                                        case 0:
                                                db->arc_pts[i][0] = v1;
                                                db->arc_pts[i][1] = v2;
                                                break;
                                        case 1:
                                                db->arc_pts[i][0] = v2;
                                                db->arc_pts[i][1] = v3;
                                                break;

                                        case 2:
                                                db->arc_pts[i][0] = v2;
                                                db->arc_pts[i][1] = v4;
                                                break;

                                        default:
                                                Int3();
                                        }
                                                
                                        n++;
                                        if ( n == n_arcs )
                                                break;  // Don't need to create anymore
                                }
                        }

        
                        // rotate v2 out of local coordinates into world.
                        // Use v2 since it is used in every bolt.  See above switch().
                        vector snd_pos;
                        vm_vec_unrotate(&snd_pos, &v2, &obj->orient);
                        vm_vec_add2(&snd_pos, &obj->pos );

                        //Play a sound effect
                        if ( lifetime > 750 )   {
                                // 1.00 second effect
                                snd_play_3d( &Snds[SND_DEBRIS_ARC_05], &snd_pos, &View_position, obj->radius );
                        } else if ( lifetime >  500 )   {
                                // 0.75 second effect
                                snd_play_3d( &Snds[SND_DEBRIS_ARC_04], &snd_pos, &View_position, obj->radius );
                        } else if ( lifetime >  250 )   {
                                // 0.50 second effect
                                snd_play_3d( &Snds[SND_DEBRIS_ARC_03], &snd_pos, &View_position, obj->radius );
                        } else if ( lifetime >  100 )   {
                                // 0.25 second effect
                                snd_play_3d( &Snds[SND_DEBRIS_ARC_02], &snd_pos, &View_position, obj->radius );
                        } else {
                                // 0.10 second effect
                                snd_play_3d( &Snds[SND_DEBRIS_ARC_01], &snd_pos, &View_position, obj->radius );
                        }

                }



        }

        for (i=0; i<MAX_DEBRIS_ARCS; i++ )      {
                if ( timestamp_valid( db->arc_timestamp[i] ) )  {
                        if ( timestamp_elapsed( db->arc_timestamp[i] ) )        {
                                // Kill off the spark
                                db->arc_timestamp[i] = timestamp(-1);
                        } else {
                                // Maybe move a vertex....  20% of the time maybe?
                                int mr = myrand();
                                if ( mr < RAND_MAX/5 )  {
                                        vector v1, v2;
                                        submodel_get_two_random_points( db->model_num, db->submodel_num, &v1, &v2 );
                                        db->arc_pts[i][mr % 2] = v1;
                                }
                        }
                }
        }

}

// ---------------------------------------------------------------------------------------
// debris_find_oldest()
//
// Locate the oldest hull debris chunk.  Search through the Hull_debris_list, which is a list
// of all the hull debris chunks.
//
int debris_find_oldest()
{
        int             oldest_index;
        fix             oldest_time;
        debris  *db;

        oldest_index = -1;
        oldest_time = 0x7fffffff;

        for ( db = GET_FIRST(&Hull_debris_list); db != END_OF_LIST(&Hull_debris_list); db = GET_NEXT(db) ) {
                if ( (db->time_started < oldest_time) && !(Objects[db->objnum].flags & OF_SHOULD_BE_DEAD) ) {
                        oldest_index = DEBRIS_INDEX(db);
                        oldest_time = db->time_started;
                }
        }

        return oldest_index;
}

#define DEBRIS_ROTVEL_SCALE     5.0f
void calc_debris_physics_properties( physics_info *pi, vector *min, vector *max );
// ---------------------------------------------------------------------------------------
// debris_create()
//
// Create debris from an object
//
//      exp_force:      Explosion force, used to assign velocity to pieces.
//                                      1.0f assigns velocity like before.  2.0f assigns twice as much to non-inherited part of velocity
object *debris_create(object *source_obj, int model_num, int submodel_num, vector *pos, vector *exp_center, int hull_flag, float exp_force)
{
        int             i, n, objnum, parent_objnum;
        object  *obj;
        ship            *shipp;
        debris  *db;    
        polymodel *pm;
        int vaporize;

        parent_objnum = OBJ_INDEX(source_obj);

        Assert( (source_obj->type == OBJ_SHIP ) || (source_obj->type == OBJ_GHOST));
        Assert( source_obj->instance >= 0 && source_obj->instance < MAX_SHIPS );        
        shipp = &Ships[source_obj->instance];
        vaporize = (shipp->flags &SF_VAPORIZE);

        if ( !hull_flag )       {
                // Make vaporize debris seen from farther away
                float dist = vm_vec_dist_quick( pos, &Eye_position );
                if (vaporize) {
                        dist /= 2.0f;
                }
                if ( dist > 200.0f ) {
                        //mprintf(( "Not creating debris that is %.1f m away\n", dist ));
                        return NULL;
                }
        }

        if ( hull_flag && (Num_hull_pieces >= MAX_HULL_PIECES ) ) {
                // cause oldest hull debris chunk to blow up
                n = debris_find_oldest();
                if ( n >= 0 ) {
                        debris_start_death_roll(&Objects[Debris[n].objnum], &Debris[n] );
                }
        }

        for (n=0; n<MAX_DEBRIS_PIECES; n++ ) {
                if ( !(Debris[n].flags & DEBRIS_USED) )
                        break;
        }

        if ( n == MAX_DEBRIS_PIECES ) {
                nprintf(("Warning","Frame %i: Could not create debris, no more slots left\n", Framecount));
                return NULL;
        }

        db = &Debris[n];

        // Create Debris piece n!
        if ( hull_flag ) {
                if (rand() < RAND_MAX/6)        // Make some pieces blow up shortly after explosion.
                        db->lifeleft = 2.0f * ((float) myrand()/(float) RAND_MAX) + 0.5f;
                else
                        db->lifeleft = -1.0f;           // large hull pieces stay around forever
        }       else {
                db->lifeleft = (i2fl(myrand())/i2fl(RAND_MAX))*2.0f+0.1f;
        }

        // increase lifetime for vaporized debris
        if (vaporize) {
                db->lifeleft *= 3.0f;
        }
        db->flags |= DEBRIS_USED;
        db->is_hull = hull_flag;
        db->source_objnum = parent_objnum;
        db->source_sig = source_obj->signature;
        db->ship_info_index = shipp->ship_info_index;
        db->team = shipp->team;
        db->fire_timeout = 0;   // if not changed, timestamp_elapsed() will return false
        db->time_started = Missiontime;
        db->species = Ship_info[shipp->ship_info_index].species;
        db->next_distance_check = (myrand() % 2000) + 4*DEBRIS_DISTANCE_CHECK_TIME;

        for (i=0; i<MAX_DEBRIS_ARCS; i++ )      {
                db->arc_timestamp[i] = timestamp(-1);
                //      vector  arc_pts[MAX_DEBRIS_ARCS][2];            // The endpoints of each arc
        }

        if ( db->is_hull )      {
                // Only make 1/2 of the pieces have arcs
                if ( myrand() < RAND_MAX*2/3 )  {
                        db->arc_frequency = 1000;
                } else {
                        db->arc_frequency = 0;
                }
        } else {
                db->arc_frequency = 0;
        }

        if ( model_num < 0 )    {
                if (vaporize) {
                        db->model_num = Debris_vaporize_model;
                } else {
                        db->model_num = Debris_model;
                }
                db->submodel_num = (myrand()>>4) % Debris_num_submodels;
        } else {
                db->model_num = model_num;
                db->submodel_num = submodel_num;
        }
        float radius = submodel_get_radius( db->model_num, db->submodel_num );

        db->next_fireball = timestamp_rand(500,2000);   //start one 1/2 - 2 secs later

        if ( pos == NULL )
                pos = &source_obj->pos;

        uint flags = OF_RENDERS | OF_PHYSICS;
        if ( hull_flag )        
                flags |= OF_COLLIDES;
        objnum = obj_create( OBJ_DEBRIS, parent_objnum, n, &source_obj->orient, pos, radius, flags );
        if ( objnum == -1 ) {
                mprintf(("Couldn't create debris object -- out of object slots\n"));
                return NULL;
        }

        db->objnum = objnum;
        
        obj = &Objects[objnum];

        // assign the network signature.  The signature will be 0 for non-hull pieces, but since that
        // is our invalid signature, it should be okay.
        obj->net_signature = 0;
        if ( (Game_mode & GM_MULTIPLAYER) && hull_flag ) {
                obj->net_signature = multi_get_next_network_signature( MULTI_SIG_DEBRIS );
        }

        // -- No long need shield: bset_shield_strength(obj, 100.0f);           //      Hey!  Set to some meaningful value!

        if (source_obj->type == OBJ_SHIP) {
                obj->hull_strength = Ship_info[Ships[source_obj->instance].ship_info_index].initial_hull_strength/8.0f;
        } else
                obj->hull_strength = 10.0f;

        Num_debris_pieces++;

        vector rotvel, radial_vel, to_center;

        if ( exp_center )
                vm_vec_sub( &to_center,pos, exp_center );
        else
                vm_vec_zero(&to_center);

        float scale;

        if ( hull_flag )        {
                float t;
                scale = exp_force * i2fl((myrand()%20) + 10);   // for radial_vel away from location of blast center
                db->sound_delay = timestamp(DEBRIS_SOUND_DELAY);

                // set up physics mass and I_inv for hull debris pieces
                pm = model_get(model_num);
                vector *min, *max;
                min = &pm->submodel[submodel_num].min;
                max = &pm->submodel[submodel_num].max;
                calc_debris_physics_properties( &obj->phys_info, min, max );

                // limit the amount of time that fireballs appear
                // let fireball length be linked to radius of ship.  Range is .33 radius => 3.33 radius seconds.
                t = 1000*Objects[db->source_objnum].radius/3 + myrand()%(fl2i(1000*3*Objects[db->source_objnum].radius));
                db->fire_timeout = timestamp(fl2i(t));          // fireballs last from 5 - 30 seconds
                
                if ( Objects[db->source_objnum].radius < MIN_RADIUS_FOR_PERSISTANT_DEBRIS ) {
                        db->flags |= DEBRIS_EXPIRE;     // debris can expire
                        Num_hull_pieces++;
                        list_append(&Hull_debris_list, db);
                } else {
                        nprintf(("Alan","A forever chunk of debris was created from ship with radius %f\n",Objects[db->source_objnum].radius));
                }
        }
        else {
                scale = exp_force * i2fl((myrand()%20) + 10);   // for radial_vel away from blast center (non-hull)
        }

        if ( vm_vec_mag_squared( &to_center ) < 0.1f )  {
                vm_vec_rand_vec_quick(&radial_vel);
                vm_vec_scale(&radial_vel, scale );
        }
        else {
                vm_vec_normalize(&to_center);
                vm_vec_copy_scale(&radial_vel, &to_center, scale );
        }

        //      MK: This next line causes debris pieces to get between 50% and 100% of the parent ship's
        //      velocity.  What would be very cool is if the rotational velocity of the parent would become 
        // translational velocity of the debris piece.  This would be based on the location of the debris
        //      piece in the parent object.

        // DA: here we need to vel_from_rot = w x to_center, where w is world is unrotated to world coords and offset is the 
        // displacement fromt the center of the parent object to the center of the debris piece

        vector world_rotvel, vel_from_rotvel;
        vm_vec_unrotate ( &world_rotvel, &source_obj->phys_info.rotvel, &source_obj->orient );
        vm_vec_crossprod ( &vel_from_rotvel, &world_rotvel, &to_center );
        vm_vec_scale ( &vel_from_rotvel, DEBRIS_ROTVEL_SCALE);

        vm_vec_add (&obj->phys_info.vel, &radial_vel, &source_obj->phys_info.vel);
        vm_vec_add2(&obj->phys_info.vel, &vel_from_rotvel);

#ifdef DEBRIS_SPEED_DEBUG
        // check that debris is not created with too high a velocity
        if (hull_flag) {
                int ship_info_flag = Ship_info[Ships[source_obj->instance].ship_info_index].flags;
                if (ship_info_flag & (SIF_SMALL_SHIP | SIF_NOT_FLYABLE | SIF_HARMLESS)) {
                        if (vm_vec_mag_squared(&obj->phys_info.vel) > MAX_SPEED_SMALL_DEBRIS*MAX_SPEED_SMALL_DEBRIS) {
                                float scale = MAX_SPEED_SMALL_DEBRIS / vm_vec_mag(&obj->phys_info.vel);
                                vm_vec_scale(&obj->phys_info.vel, scale);
                        }
                } else if (ship_info_flag & SIF_BIG_SHIP) {
                        if (vm_vec_mag_squared(&obj->phys_info.vel) > MAX_SPEED_BIG_DEBRIS*MAX_SPEED_BIG_DEBRIS) {
                                float scale = MAX_SPEED_BIG_DEBRIS / vm_vec_mag(&obj->phys_info.vel);
                                vm_vec_scale(&obj->phys_info.vel, scale);
                        }
                } else if (ship_info_flag & SIF_HUGE_SHIP) {
                        if (vm_vec_mag_squared(&obj->phys_info.vel) > MAX_SPEED_CAPITAL_DEBRIS*MAX_SPEED_CAPITAL_DEBRIS) {
                                float scale = MAX_SPEED_CAPITAL_DEBRIS / vm_vec_mag(&obj->phys_info.vel);
                                vm_vec_scale(&obj->phys_info.vel, scale);
                        }
                } else {
                        Warning(LOCATION, "Ship has info flag that is not among the following:  SMALL, NOT_FLYABLE, HARMLESS, BIG, CAPITAL, SUPERCAP");
                }
        }
#endif

//      vm_vec_scale_add(&obj->phys_info.vel, &radial_vel, &source_obj->phys_info.vel, frand()/2.0f + 0.5f);
//      nprintf(("Andsager","object vel from rotvel: %0.2f, %0.2f, %0.2f\n",vel_from_rotvel.x, vel_from_rotvel.y, vel_from_rotvel.z));

// make sure rotational velocity does not get too high
        if (radius < 1.0) {
                radius = 1.0f;
        }

        scale = ( 6.0f + i2fl(myrand()%4) ) / radius;

        vm_vec_rand_vec_quick(&rotvel);
        vm_vec_scale(&rotvel, scale);

        obj->phys_info.flags |= PF_DEAD_DAMP;
        obj->phys_info.rotvel = rotvel;
        check_rotvel_limit( &obj->phys_info );


        // blow out his reverse thrusters. Or drag, same thing.
        obj->phys_info.rotdamp = 10000.0f;
        obj->phys_info.side_slip_time_const = 10000.0f;
        obj->phys_info.flags |= (PF_REDUCED_DAMP | PF_DEAD_DAMP);       // set damping equal for all axis and not changable

        vm_vec_zero(&obj->phys_info.max_vel);           // make so he can't turn on his own VOLITION anymore.
        vm_vec_zero(&obj->phys_info.max_rotvel);        // make so he can't change speed on his own VOLITION anymore.


        // ensure vel is valid
        Assert( !vm_is_vec_nan(&obj->phys_info.vel) );

//      if ( hull_flag )        {
//              vm_vec_zero(&obj->phys_info.vel);
//              vm_vec_zero(&obj->phys_info.rotvel);
//      }

        return obj;
}

// ---------------------------------------------------------------------------------------
// debris_hit()
//
//      Alas, poor debris_obj got whacked.  Fortunately, we know who did it, where and how hard, so we
//      can do something about it.
//
void debris_hit(object *debris_obj, object *other_obj, vector *hitpos, float damage)
{
        debris  *debris_p = &Debris[debris_obj->instance];


        // Do a little particle spark shower to show we hit
        {
                particle_emitter        pe;

                pe.pos = *hitpos;                                                               // Where the particles emit from
                pe.vel = debris_obj->phys_info.vel;             // Initial velocity of all the particles

                vector tmp_norm;
                vm_vec_sub( &tmp_norm, hitpos, &debris_obj->pos );
                vm_vec_normalize_safe(&tmp_norm);
                        
                pe.normal = tmp_norm;                   // What normal the particle emit around
                pe.normal_variance = 0.3f;              //      How close they stick to that normal 0=good, 1=360 degree
                pe.min_rad = 0.20f;                             // Min radius
                pe.max_rad = 0.40f;                             // Max radius

                // Sparks for first time at this spot
                pe.num_low = 10;                                // Lowest number of particles to create
                pe.num_high = 10;                       // Highest number of particles to create
                pe.normal_variance = 0.3f;              //      How close they stick to that normal 0=good, 1=360 degree
                pe.min_vel = 0.0f;                              // How fast the slowest particle can move
                pe.max_vel = 10.0f;                             // How fast the fastest particle can move
                pe.min_life = 0.25f;                    // How long the particles live
                pe.max_life = 0.75f;                    // How long the particles live
                particle_emit( &pe, PARTICLE_FIRE, 0 );
        }

        // multiplayer clients bail here
        if(MULTIPLAYER_CLIENT){
                return;
        }

        if ( damage < 0.0f ) {
                damage = 0.0f;
        }

        debris_obj->hull_strength -= damage;

        if (debris_obj->hull_strength < 0.0f) {
                debris_start_death_roll(debris_obj, debris_p );
        } else {
                // otherwise, give all the other players an update on the debris
                if(MULTIPLAYER_MASTER){
                        send_debris_update_packet(debris_obj,DEBRIS_UPDATE_UPDATE);
                }
        }
}

// ---------------------------------------------------------------------------------------
// debris_check_collision()
//
//      See if poor debris object *obj got whacked by evil *other_obj at point *hitpos.
// NOTE: debris_hit_info pointer NULL for debris:weapon collision, otherwise debris:ship collision.
//      Return true if hit, else return false.
//
#ifndef PLAT_UNIX
#pragma warning ( push )
#pragma warning ( disable : 4701 )
#endif
int debris_check_collision(object *pdebris, object *other_obj, vector *hitpos, collision_info_struct *debris_hit_info)
{
        mc_info mc;
        int             num;

        Assert( pdebris->type == OBJ_DEBRIS );

        num = pdebris->instance;
        Assert( num >= 0 );

        Assert( Debris[num].objnum == OBJ_INDEX(pdebris));      

        // debris_hit_info NULL - so debris-weapon collision
        if ( debris_hit_info == NULL ) {
                // debris weapon collision
                Assert( other_obj->type == OBJ_WEAPON );
                mc.model_num = Debris[num].model_num;   // Fill in the model to check
                mc.submodel_num = Debris[num].submodel_num;
                model_clear_instance( mc.model_num );
                mc.orient = &pdebris->orient;                                   // The object's orient
                mc.pos = &pdebris->pos;                                                 // The object's position
                mc.p0 = &other_obj->last_pos;                           // Point 1 of ray to check
                mc.p1 = &other_obj->pos;                                        // Point 2 of ray to check
                mc.flags = (MC_CHECK_MODEL | MC_SUBMODEL);

                if (model_collide(&mc)) {
                        *hitpos = mc.hit_point_world;
                }

                return mc.num_hits;
        }
        
        // debris ship collision -- use debris_hit_info to calculate physics
        object *ship_obj = other_obj;
        Assert( ship_obj->type == OBJ_SHIP );

        object *heavy = debris_hit_info->heavy;
        object *light = debris_hit_info->light;
        object *heavy_obj = heavy;
        object *light_obj = light;

        vector zero, p0, p1;
        vm_vec_zero(&zero);
        vm_vec_sub(&p0, &light->last_pos, &heavy->last_pos);
        vm_vec_sub(&p1, &light->pos, &heavy->pos);

        mc.pos = &zero;                                                         // The object's position
        mc.p0 = &p0;                                                                    // Point 1 of ray to check
        mc.p1 = &p1;                                                                    // Point 2 of ray to check

        // find the light object's position in the heavy object's reference frame at last frame and also in this frame.
        vector p0_temp, p0_rotated;
                
        // Collision detection from rotation enabled if at rotaion is less than 30 degree in frame
        // This should account for all ships
        if ( (vm_vec_mag_squared(&heavy->phys_info.rotvel) * flFrametime*flFrametime) < (PI*PI/36) ) {
                // collide_rotate calculate (1) start position and (2) relative velocity
                debris_hit_info->collide_rotate = 1;
                vm_vec_rotate(&p0_temp, &p0, &heavy->last_orient);
                vm_vec_unrotate(&p0_rotated, &p0_temp, &heavy->orient);
                mc.p0 = &p0_rotated;                            // Point 1 of ray to check
                vm_vec_sub(&debris_hit_info->light_rel_vel, &p1, &p0_rotated);
                vm_vec_scale(&debris_hit_info->light_rel_vel, 1/flFrametime);
        } else {
                debris_hit_info->collide_rotate = 0;
                vm_vec_sub(&debris_hit_info->light_rel_vel, &light->phys_info.vel, &heavy->phys_info.vel);
        }

        int mc_ret_val = 0;

        if ( debris_hit_info->heavy == ship_obj ) {     // ship is heavier, so debris is sphere. Check sphere collision against ship poly model
                mc.model_num = Ships[ship_obj->instance].modelnum;              // Fill in the model to check
                mc.orient = &ship_obj->orient;                                                          // The object's orient
                mc.radius = pdebris->radius;
                mc.flags = (MC_CHECK_MODEL | MC_CHECK_SPHERELINE);

                // copy important data
                int copy_flags = mc.flags;  // make a copy of start end positions of sphere in  big ship RF
                vector copy_p0, copy_p1;
                copy_p0 = *mc.p0;
                copy_p1 = *mc.p1;

                // first test against the sphere - if this fails then don't do any submodel tests
                mc.flags = MC_ONLY_SPHERE | MC_CHECK_SPHERELINE;

                int submodel_list[MAX_ROTATING_SUBMODELS];
                int num_rotating_submodels = 0;
                polymodel *pm;

                ship_model_start(ship_obj);

                if (model_collide(&mc)) {

                        // Set earliest hit time
                        debris_hit_info->hit_time = FLT_MAX;

                        // Do collision the cool new way
                        if ( debris_hit_info->collide_rotate ) {
                                // We collide with the sphere, find the list of rotating submodels and test one at a time
                                model_get_rotating_submodel_list(submodel_list, &num_rotating_submodels, heavy_obj);

                                // Get polymodel and turn off all rotating submodels, collide against only 1 at a time.
                                pm = model_get(Ships[heavy_obj->instance].modelnum);

                                // turn off all rotating submodels and test for collision
                                for (int i=0; i<num_rotating_submodels; i++) {
                                        pm->submodel[submodel_list[i]].blown_off = 1;
                                }

                                // reset flags to check MC_CHECK_MODEL | MC_CHECK_SPHERELINE and maybe MC_CHECK_INVISIBLE_FACES and MC_SUBMODEL_INSTANCE
                                mc.flags = copy_flags | MC_SUBMODEL_INSTANCE;

                                // check each submodel in turn
                                for (int i=0; i<num_rotating_submodels; i++) {
                                        // turn on submodel for collision test
                                        pm->submodel[submodel_list[i]].blown_off = 0;

                                        // set angles for last frame (need to set to prev to get p0)
                                        angles copy_angles = pm->submodel[submodel_list[i]].angs;

                                        // find the start and end positions of the sphere in submodel RF
                                        pm->submodel[submodel_list[i]].angs = pm->submodel[submodel_list[i]].sii->prev_angs;
                                        world_find_model_point(&p0, &light_obj->last_pos, pm, submodel_list[i], &heavy_obj->last_orient, &heavy_obj->last_pos);

                                        pm->submodel[submodel_list[i]].angs = copy_angles;
                                        world_find_model_point(&p1, &light_obj->pos, pm, submodel_list[i], &heavy_obj->orient, &heavy_obj->pos);

                                        mc.p0 = &p0;
                                        mc.p1 = &p1;
                                        // mc.pos = zero        // in submodel RF

                                        mc.orient = &vmd_identity_matrix;
                                        mc.submodel_num = submodel_list[i];

                                        if ( model_collide(&mc) ) {
                                                if ( mc.hit_dist < debris_hit_info->hit_time ) {
                                                        mc_ret_val = 1;

                                                        // set up debris_hit_info common
                                                        set_hit_struct_info(debris_hit_info, &mc, SUBMODEL_ROT_HIT);
                                                        model_find_world_point(&debris_hit_info->hit_pos, &mc.hit_point, mc.model_num, mc.hit_submodel, &heavy_obj->orient, &zero);

                                                        // set up debris_hit_info for rotating submodel
                                                        if (debris_hit_info->edge_hit == 0) {
                                                                model_find_obj_dir(&debris_hit_info->collision_normal, &mc.hit_normal, heavy_obj, mc.hit_submodel);
                                                        }

                                                        // find position in submodel RF of light object at collison
                                                        vector int_light_pos, diff;
                                                        vm_vec_sub(&diff, mc.p1, mc.p0);
                                                        vm_vec_scale_add(&int_light_pos, mc.p0, &diff, mc.hit_dist);
                                                        model_find_world_point(&debris_hit_info->light_collision_cm_pos, &int_light_pos, mc.model_num, mc.hit_submodel, &heavy_obj->orient, &zero);
                                                }
                                        }
                                        // Don't look at this submodel again
                                        pm->submodel[submodel_list[i]].blown_off = 1;
                                }

                        }

                        // Recover and do usual ship_ship collision, but without rotating submodels
                        mc.flags = copy_flags;
                        *mc.p0 = copy_p0;
                        *mc.p1 = copy_p1;
                        mc.orient = &heavy_obj->orient;

                        // usual ship_ship collision test
                        if ( model_collide(&mc) )       {
                                // check if this is the earliest hit
                                if (mc.hit_dist < debris_hit_info->hit_time) {
                                        mc_ret_val = 1;

                                        set_hit_struct_info(debris_hit_info, &mc, SUBMODEL_NO_ROT_HIT);

                                        // get collision normal if not edge hit
                                        if (debris_hit_info->edge_hit == 0) {
                                                model_find_obj_dir(&debris_hit_info->collision_normal, &mc.hit_normal, heavy_obj, mc.hit_submodel);
                                        }

                                        // find position in submodel RF of light object at collison
                                        vector diff;
                                        vm_vec_sub(&diff, mc.p1, mc.p0);
                                        vm_vec_scale_add(&debris_hit_info->light_collision_cm_pos, mc.p0, &diff, mc.hit_dist);

                                }
                        }

                        ship_model_stop( ship_obj );
                }

        } else {
                // Debris is heavier obj
                mc.model_num = Debris[num].model_num;           // Fill in the model to check
                mc.submodel_num = Debris[num].submodel_num;
                model_clear_instance( mc.model_num );
                mc.orient = &pdebris->orient;                           // The object's orient
                mc.radius = model_get_core_radius( Ships[ship_obj->instance].modelnum );

                // check for collision between debris model and ship sphere
                mc.flags = (MC_CHECK_MODEL | MC_SUBMODEL | MC_CHECK_SPHERELINE);

                mc_ret_val = model_collide(&mc);

                if (mc_ret_val) {
                        set_hit_struct_info(debris_hit_info, &mc, SUBMODEL_NO_ROT_HIT);

                        // set normal if not edge hit
                        if ( !debris_hit_info->edge_hit ) {
                                vm_vec_unrotate(&debris_hit_info->collision_normal, &mc.hit_normal, &heavy->orient);
                        }

                        // find position in submodel RF of light object at collison
                        vector diff;
                        vm_vec_sub(&diff, mc.p1, mc.p0);
                        vm_vec_scale_add(&debris_hit_info->light_collision_cm_pos, mc.p0, &diff, mc.hit_dist);

                }
        }


        if ( mc_ret_val )       {

                // SET PHYSICS PARAMETERS
                // already have (hitpos - heavy) and light_cm_pos
                // get heavy cm pos - already have light_cm_pos
                debris_hit_info->heavy_collision_cm_pos = zero;

                // get r_heavy and r_light
                debris_hit_info->r_heavy = debris_hit_info->hit_pos;
                vm_vec_sub(&debris_hit_info->r_light, &debris_hit_info->hit_pos, &debris_hit_info->light_collision_cm_pos);

                // set normal for edge hit
                if ( debris_hit_info->edge_hit ) {
                        vm_vec_copy_normalize(&debris_hit_info->collision_normal, &debris_hit_info->r_light);
                        vm_vec_negate(&debris_hit_info->collision_normal);
                }

                // get world hitpos
                vm_vec_add(hitpos, &debris_hit_info->heavy->pos, &debris_hit_info->r_heavy);

                return 1;
        } else {
                // no hit
                return 0;
        }
}
#ifndef PLAT_UNIX
#pragma warning ( pop )
#endif

// ---------------------------------------------------------------------------------------
// debris_get_team()
//
//      Return the team field for a debris object
//
int debris_get_team(object *objp)
{
        Assert( objp->type == OBJ_DEBRIS );
        Assert( objp->instance >= 0 && objp->instance < MAX_DEBRIS_PIECES );
        return Debris[objp->instance].team;
}

// fills in debris physics properties when created, specifically mass and moment of inertia
void calc_debris_physics_properties( physics_info *pi, vector *mins, vector *maxs )
{
        float dx, dy, dz, mass;
        dx = maxs->xyz.x - mins->xyz.x;
        dy = maxs->xyz.y - mins->xyz.y;
        dz = maxs->xyz.z - mins->xyz.z;

        // John, with new bspgen, just set pi->mass = mass
        mass = 0.12f * dx * dy * dz;
        pi->mass = (float) pow(mass, 0.6666667f) * 4.65f;

        pi->I_body_inv.v.rvec.xyz.x = 12.0f / (pi->mass *  (dy*dy + dz*dz));
        pi->I_body_inv.v.rvec.xyz.y = 0.0f;
        pi->I_body_inv.v.rvec.xyz.z = 0.0f;

        pi->I_body_inv.v.uvec.xyz.x = 0.0f;
        pi->I_body_inv.v.uvec.xyz.y = 12.0f / (pi->mass *  (dx*dx + dz*dz));
        pi->I_body_inv.v.uvec.xyz.z = 0.0f;

        pi->I_body_inv.v.fvec.xyz.x = 0.0f;
        pi->I_body_inv.v.fvec.xyz.y = 0.0f;
        pi->I_body_inv.v.fvec.xyz.z = 12.0f / (pi->mass *  (dx*dx + dy*dy));
}