*** collision.c.orig	Mon Apr 27 08:38:12 1998
--- collision.c	Mon May  4 00:51:30 1998
***************
*** 59,65 ****
  #define in_range(o1, o2, r)			\
      (DELTA((o1)->pos.x, (o2)->pos.x) < (r)	\
       && DELTA((o1)->pos.y, (o2)->pos.y) < (r))
! #else
  /* proposed edgewrap version: */
  #define in_range(o1, o2, r)						\
      (BIT(World.rules->mode, WRAP_PLAY)					\
--- 59,67 ----
  #define in_range(o1, o2, r)			\
      (DELTA((o1)->pos.x, (o2)->pos.x) < (r)	\
       && DELTA((o1)->pos.y, (o2)->pos.y) < (r))
! #endif
! 
! #if 0
  /* proposed edgewrap version: */
  #define in_range(o1, o2, r)						\
      (BIT(World.rules->mode, WRAP_PLAY)					\
***************
*** 81,86 ****
--- 83,151 ----
  	&& DELTA((o1)->pos.y, (o2)->pos.y) < (r)))
  #endif
  
+ /* The very first "analytical" collision patch, XPilot 3.6.2
+    Faster than other patches and accurate below half warp-speed
+    Trivial common subexpressions are eliminated by any reasonable compiler,
+    and kept here for readability.
+    Written by Pontus (Rakk, Kepler) pontus@ctrl-c.liu.se Jan 1998
+    Kudos to Svenske and Mad Gurka for beta testing, and Murx for
+    being a collision patch pioneer.
+    */
+ 
+ int in_range(int p1x,int p1y,int p2x,int p2y,int q1x,int q1y,int q2x,int q2y,int r) {
+ 
+   long fac1,fac2;
+   double tmin,fminx,fminy;
+   long top,bot;
+   bool mpx,mpy,mqx,mqy;
+ 
+   /* Get the wrapped coordinates straight */
+   if (BIT(World.rules->mode, WRAP_PLAY)) {
+     if ((mpx = (ABS(p2x-p1x)>World.width/2))) {
+       if (p1x>p2x) p1x-=World.width; else p2x-=World.width;
+     }
+     if ((mpy = (ABS(p2y-p1y)>World.height/2))) {
+       if (p1y>p2y) p1y-=World.height; else p2y-=World.height;
+     }
+     if ((mqx = (ABS(q2x-q1x)>World.width/2))) {
+       if (q1x>q2x) q1x-=World.width; else q2x-=World.width;
+     }
+     if ((mqy = (ABS(q2y-q1y)>World.height/2))) {
+       if (q1y>q2y) q1y-=World.height; else q2y-=World.height;
+     }
+ 
+     if (mpx && !mqx && (q2x>World.width/2 || q1x>World.width/2)) {
+       q1x-=World.width; q2x-=World.width;
+     }
+ 
+     if (mqy && !mpy && (q2y>World.height/2 || q1y>World.height/2)) {
+       q1y-=World.height; q2y-=World.height;
+     }
+ 
+     if (mqx && !mpx && (p2x>World.width/2 || p1x>World.width/2)) {
+       p1x-=World.width; p2x-=World.width;
+     }
+ 
+     if (mqy && !mpy && (p2y>World.height/2 || p1y>World.height/2)) {
+       p1y-=World.height; p2y-=World.height;
+     }
+ 
+   }
+ 
+   /* Do the detection */
+   if ((p2x-q2x)*(p2x-q2x)+(p2y-q2y)*(p2y-q2y) < r*r) return 1;
+   fac1=-p1x+p2x+q1x-q2x;
+   fac2=-p1y+p2y+q1y-q2y;
+   top=-(fac1*(-p2x+q2x)+fac2*(-p2y+q2y));
+   bot=(fac1*fac1+fac2*fac2);
+   if (top<0 || bot<1 || top>bot) return 0;
+   tmin=((double) top)/((double) bot);
+   fminx=-p2x+q2x+fac1*tmin;
+   fminy=-p2y+q2y+fac2*tmin;
+   if (fminx*fminx+fminy*fminy<r*r) return 1; else return 0;
+ }
+ 
+ 
  /*
   * Globals
   */
***************
*** 332,339 ****
  		}
  		if (BIT(Players[j]->used, OBJ_PHASING_DEVICE))
  		    continue;
! 		if (!in_range((object *)pl, (object *)Players[j],
! 				2*SHIP_SZ-6)) {
  		    continue;
  		}
  
--- 397,406 ----
  		}
  		if (BIT(Players[j]->used, OBJ_PHASING_DEVICE))
  		    continue;
! 		if (!in_range(pl->prevpos.x,pl->prevpos.y,pl->pos.x,pl->pos.y,
! 			Players[j]->prevpos.x,Players[j]->prevpos.y,
! 			Players[j]->pos.x,Players[j]->pos.y,
! 			2*SHIP_SZ-6)){
  		    continue;
  		}
  
***************
*** 685,691 ****
  	}
  
  	range = SHIP_SZ + obj->pl_range;
! 	if (!in_range((object *)pl, obj, range))
  	    continue;
  
  	if (obj->id != -1) {
--- 752,760 ----
  	}
  
  	range = SHIP_SZ + obj->pl_range;
! 	if (!in_range(pl->prevpos.x,pl->prevpos.y,pl->pos.x,pl->pos.y,
! 		obj->prevpos.x,obj->prevpos.y,obj->pos.x,obj->pos.y,
! 		range))
  	    continue;
  
  	if (obj->id != -1) {
***************
*** 723,729 ****
  	 * Objects actually only hit the player if they are really close.
  	 */
  	radius = SHIP_SZ + obj->pl_radius;
! 	hit = (radius >= range || in_range((object *)pl, obj, radius));
  	rel_velocity = LENGTH(pl->vel.x - obj->vel.x, pl->vel.y - obj->vel.y);
  
  	/*
--- 792,801 ----
  	 * Objects actually only hit the player if they are really close.
  	 */
  	radius = SHIP_SZ + obj->pl_radius;
! 	hit = (radius >= range ||
! 	in_range(pl->prevpos.x,pl->prevpos.y,pl->pos.x,pl->pos.y,
! 		obj->prevpos.x,obj->prevpos.y,obj->pos.x,obj->pos.y,
! 		range));
  	rel_velocity = LENGTH(pl->vel.x - obj->vel.x, pl->vel.y - obj->vel.y);
  
  	/*
*** walls.c.orig	Tue Apr 21 11:29:49 1998
--- walls.c	Mon May  4 00:51:00 1998
***************
*** 1831,1836 ****
--- 1831,1838 ----
      int			dist;
      move_info_t		mi;
      move_state_t	ms;
+     bool		pos_update = false;
+ 
  
      Object_position_remember(obj);
  
***************
*** 1873,1878 ****
--- 1875,1881 ----
      for (;;) {
  	Move_segment(&ms);
  	if (!(ms.done.x | ms.done.y)) {
+ 	    pos_update |= ( ms.crash || ms.bounce);
  	    if (ms.crash) {
  		break;
  	    }
***************
*** 1935,1940 ****
--- 1938,1944 ----
      if (ms.crash) {
  	Object_crash(&ms);
      }
+     if (pos_update) Object_position_remember(obj);
  }
  
  static void Player_crash(move_state_t *ms, int pt, bool turning)
***************
*** 2125,2130 ****
--- 2129,2135 ----
      vector		r[RES];
      ivec		sign;		/* sign (-1 or 1) of direction */
      ipos		block;		/* block index */
+     bool		pos_update = false;
  
  
      if (BIT(pl->status, PLAYING|PAUSE|GAME_OVER|KILLED) != PLAYING) {
***************
*** 2252,2257 ****
--- 2257,2263 ----
  	crash = -1;
  	for (i = 0; i < pl->ship->num_points; i++) {
  	    Move_segment(&ms[i]);
+ 	    pos_update |= (ms[i].crash || ms[i].bounce);
  	    if (ms[i].crash) {
  		crash = i;
  		break;
***************
*** 2448,2453 ****
--- 2454,2460 ----
      if (ms[worst].crash) {
  	Player_crash(&ms[worst], worst, false);
      }
+     if (pos_update) Player_position_remember(pl);
  }
  
  void Turn_player(int ind)