From 67c4d16d9276f1761fcb437cb2ebf1ab52067296 Mon Sep 17 00:00:00 2001
From: Rob Pearce <rob@nethack.net>
Date: Wed, 26 Nov 2008 03:24:03 +0000
Subject: [PATCH] Modified ice inertia to be more realistic

---
 data/levels/level99.dat |  16 ++--
 defs.h                  |   5 ++
 rc.c                    | 181 +++++++++++++++++++++++++++++-----------
 rc.h                    |   3 +-
 4 files changed, 145 insertions(+), 60 deletions(-)

diff --git a/data/levels/level99.dat b/data/levels/level99.dat
index 58b24b5..c3d14fc 100644
--- a/data/levels/level99.dat
+++ b/data/levels/level99.dat
@@ -6,7 +6,7 @@ endhelp
 monsters
 0 5 23
 134 37 24
-50 11 23
+6 20 10
 endmonsters
 exitdir 1
 4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
@@ -17,6 +17,11 @@ exitdir 1
 4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
 4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
 4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
+4,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
+4,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
+4,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
+4,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
+4,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
 4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
 4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
 4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
@@ -28,15 +33,10 @@ exitdir 1
 4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
 4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
 4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
+4,0,0,0,1,1,1,1,1,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,0,0,0,0,0,4,
 4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
 4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
 4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
-4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
-4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,0,4,
-4,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
-4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
-4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
-4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
-4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,
+4,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
 4,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,4,
 layer2
diff --git a/defs.h b/defs.h
index f1058d7..8321db8 100644
--- a/defs.h
+++ b/defs.h
@@ -203,6 +203,11 @@
 #define BELLTIME	20 // how long the bell flash lasts
 #define CLOCKTIME	10 // how many seconds a clock lasts
 
+
+// ice 
+#define ICEACCEL	0.1
+#define ICEDECCEL	0
+
 // blackcloud
 #define CLOUDGROWSPEED	25 // lower is faster
 #define CLOUDGROWAMT	0.01 // lower is faster
diff --git a/rc.c b/rc.c
index a3fc7cd..5f7127b 100644
--- a/rc.c
+++ b/rc.c
@@ -1396,7 +1396,6 @@ void jump(sprite_t *s, int dir) {
 				s->jumping = 1;
 				s->dir = -s->jumpdir; // face backwards
 			} else {
-				// TODO: check this (the * getspeed bit)!
 				//s->jumpdir = s->dir * getspeed(s);
 				s->jumpdir = dir;
 				if (s->jumpdir != 0) {
@@ -1449,13 +1448,17 @@ void jump(sprite_t *s, int dir) {
 					if (!haspowerup(s, P_SPEED) == 1) s->jumpdir--; // go fast even if player is slow
 				}
 			} else {
+				tt= gettileat(s->x, s->y, NULL, NULL);
 				// if on rollers, they add to your inertia 
 				// if you are facing their direction
-				tt= gettileat(s->x, s->y, NULL, NULL);
 				if ((tt->id == T_RIGHT) && (s->jumpdir > 0)) {
 					s->jumpdir++;
 				} else if ((tt->id == T_LEFT) && (s->jumpdir < 0)) {
 					s->jumpdir--;
+				} else if (isice(tt->id)) {
+					s->jumpdir = s->xs / getspeed(s);
+					//if (s->jumpdir > getspeed(s)) s->jumpdir -= getspeed(s);
+					//if (s->jumpdir < -getspeed(s)) s->jumpdir += getspeed(s);
 				}
 			}
 
@@ -2478,7 +2481,7 @@ int movesprite(sprite_t *s) {
 		}
 	} else if (s->jumping) {
 		if (s->id != P_KINGRAT) {
-			movex(s, s->jumpdir*getspeed(s));
+			movex(s, s->jumpdir*getspeed(s), B_TRUE);
 		}
 		return B_FALSE;
 	}
@@ -2964,7 +2967,7 @@ int movesprite(sprite_t *s) {
 			xpoint = (curlevel->powerupx * TILEW) + (TILEW/2);
 			if (s->x <= xpoint) {
 				int rv = B_FALSE;
-				rv = movex(s, s->speed);
+				rv = movex(s, s->speed, B_TRUE);
 			}
 		} else { // not in intro sequence
 			if (!s->falling) {
@@ -3016,7 +3019,7 @@ int movesprite(sprite_t *s) {
 		
 				/* either move or turn around */
 				if (move) {
-					rv = movex(s, s->dir*getspeed(s));
+					rv = movex(s, s->dir*getspeed(s), B_TRUE);
 					if (rv) {
 						/* if we couldn't move (hit a wall), turn */
 						s->dir = -s->dir;
@@ -3064,9 +3067,9 @@ int movesprite(sprite_t *s) {
 				tunder = gettileat(s->x ,s->y,NULL,NULL);
 				t2under = gettileat(s->x ,s->y+s->img->h,NULL,NULL);
 				if ((tunder->solid == S_SLOPE) || (t2under->solid == S_SLOPE)) {
-					movex(s, s->dir*getspeed(s));
+					movex(s, s->dir*getspeed(s), B_TRUE);
 				} else if (s->jumpdir) {
-					movex(s, s->jumpdir*getspeed(s));
+					movex(s, s->jumpdir*getspeed(s), B_TRUE);
 				}
 			}
 		} // end if inintro
@@ -3103,7 +3106,7 @@ int movesprite(sprite_t *s) {
 		
 			/* either move or turn around */
 			if (move) {
-				rv = movex(s, s->dir*getspeed(s));
+				rv = movex(s, s->dir*getspeed(s), B_TRUE);
 				if (rv) {
 					/* if we couldn't move (hit a wall), turn */
 					s->dir = -s->dir;
@@ -3149,9 +3152,9 @@ int movesprite(sprite_t *s) {
 		} else { // falling
 			if (s->recoiling) {
 				// fall backwards
-				rv = movex(s, -s->dir*getspeed(s));
+				rv = movex(s, -s->dir*getspeed(s), B_TRUE);
 			} else if (s->jumpdir) {
-				movex(s, s->jumpdir*getspeed(s));
+				movex(s, s->jumpdir*getspeed(s), B_TRUE);
 			}
 		}
 	} else if (s->id == P_SLUG) {
@@ -3199,7 +3202,7 @@ int movesprite(sprite_t *s) {
 		
 			/* either move or turn around */
 			if (move) {
-				rv = movex(s, s->dir*getspeed(s));
+				rv = movex(s, s->dir*getspeed(s), B_TRUE);
 				if (rv) {
 					/* if we couldn't move (hit a wall), turn */
 					s->dir = -s->dir;
@@ -3250,7 +3253,7 @@ int movesprite(sprite_t *s) {
 		} else { // falling
 			int rv;
 			// move forwards 
-			rv = movex(s, s->dir*getspeed(s));
+			rv = movex(s, s->dir*getspeed(s), B_TRUE);
 		}
 	} else if (s->id == P_PLANT) {
 		// don't move!
@@ -3267,7 +3270,7 @@ int movesprite(sprite_t *s) {
 			int canseeplayer = B_TRUE;
 			int ydis;
 			// move 
-			rv = movex(s, s->dir*getspeed(s));
+			rv = movex(s, s->dir*getspeed(s), B_TRUE);
 			if (rv) {
 				/* if we couldn't move (hit a wall), turn */
 				s->dir = -s->dir;
@@ -3341,7 +3344,7 @@ int movesprite(sprite_t *s) {
 		} else if (s->timer1 == KRS_CHARGE) {
 			int rv;
 			// move fast forwards
-			rv = movex(s, s->dir*KR_CHARGESPEED);
+			rv = movex(s, s->dir*KR_CHARGESPEED, B_TRUE);
 			if (rv) {
 				// hit a wall - get stunned
 				s->timer1 = KRS_STUN;
@@ -3417,7 +3420,7 @@ int movesprite(sprite_t *s) {
 		*/
 		if ((s->timer1 == KSS_WALK1) || (s->timer1 == KSS_WALK2)) {
 			// walk back and forth
-			rv = movex(s, s->dir*getspeed(s));
+			rv = movex(s, s->dir*getspeed(s), B_TRUE);
 			if (rv) {
 				/* if we couldn't move (hit a wall), turn */
 				s->dir = -s->dir;
@@ -3871,7 +3874,7 @@ printf("setting target to y = %d\n",ss->timer2);
 
 						for  (ii = 0; ii < amt; ii++) {
 							//s2->x += dir;
-							if (movex(s2, dir)) break;
+							if (movex(s2, dir, B_TRUE)) break;
 						}
 						s2->moved = oldmoved; // so that we don't animate
 						s2->y += ydiff;
@@ -3931,7 +3934,7 @@ printf("setting target to y = %d\n",ss->timer2);
 	
 			/* either move or turn around */
 			if (move) {
-				rv = movex(s, s->dir*getspeed(s));
+				rv = movex(s, s->dir*getspeed(s), B_TRUE);
 				if (rv) {
 					/* if we couldn't move (hit a wall), turn */
 					s->dir = -s->dir;
@@ -3968,7 +3971,7 @@ printf("setting target to y = %d\n",ss->timer2);
 				}
 			}
 		} else { // falling
-			movex(s, s->jumpdir*getspeed(s));
+			movex(s, s->jumpdir*getspeed(s), B_TRUE);
 		}
 	} else if (s->id == P_SNAKE) {
 		/* timer1 loopsfrom 0 - 19
@@ -4070,7 +4073,7 @@ printf("setting target to y = %d\n",ss->timer2);
 	
 			/* either move or turn around */
 			if (move) {
-				rv = movex(s, s->dir*getspeed(s));
+				rv = movex(s, s->dir*getspeed(s), B_TRUE);
 				if (rv) {
 					/* if we couldn't move (hit a wall), turn */
 					s->dir = -s->dir;
@@ -4112,7 +4115,7 @@ printf("setting target to y = %d\n",ss->timer2);
 				}
 			}
 		} else { // falling
-			movex(s, s->jumpdir*getspeed(s));
+			movex(s, s->jumpdir*getspeed(s), B_TRUE);
 		}
 
 	} else if (s->id == P_BEE) {
@@ -4343,7 +4346,7 @@ printf("setting target to y = %d\n",ss->timer2);
 			
 					/* either move or turn around */
 					if (move) {
-						rv = movex(s, s->dir*myspeed);
+						rv = movex(s, s->dir*myspeed, B_TRUE);
 						if (rv) {
 							/* if we couldn't move (hit a wall), turn */
 							s->dir = -s->dir;
@@ -4394,7 +4397,7 @@ printf("setting target to y = %d\n",ss->timer2);
 					tunder = gettileat(s->x ,s->y,NULL,NULL);
 					t2under = gettileat(s->x ,s->y+s->img->h,NULL,NULL);
 					if ((tunder->solid == S_SLOPE) || (t2under->solid == S_SLOPE)) {
-						movex(s, s->dir*myspeed);
+						movex(s, s->dir*myspeed, B_TRUE);
 						// reset walk timer
 						s->timer1 = 0;
 					}
@@ -4522,7 +4525,7 @@ printf("setting target to y = %d\n",ss->timer2);
 			
 					/* either move or turn around */
 					if (move) {
-						rv = movex(s, s->dir*getspeed(s));
+						rv = movex(s, s->dir*getspeed(s), B_TRUE);
 						if (rv) {
 							/* if we couldn't move (hit a wall), turn */
 							s->dir = -s->dir;
@@ -4534,7 +4537,7 @@ printf("setting target to y = %d\n",ss->timer2);
 			}
 		}
 	} else if (s->id == P_SPIT) {
-		if (movex(s, s->xs)) {
+		if (movex(s, s->xs, B_TRUE)) {
 			s->dead = D_FINAL;
 		}
 	} else if (s->id == P_PINKCLOUD) {
@@ -4818,9 +4821,9 @@ printf("setting target to y = %d\n",ss->timer2);
 				spd = 7 - spd;
 				if (spd > 7) spd = 7; 
 				if (who->x > s->x) {
-					movex(s, spd);
+					movex(s, spd, B_FALSE);
 				} else if (who->x < s->x) {
-					movex(s, -spd);
+					movex(s, -spd, B_FALSE);
 				}
 			}
 		}
@@ -4838,9 +4841,9 @@ printf("setting target to y = %d\n",ss->timer2);
 				spd = 7 - spd;
 				if (spd > 7) spd = 7; 
 				if (who->x > s->x) {
-					movex(s, -spd);
+					movex(s, -spd, B_TRUE);
 				} else if (who->x < s->x) {
-					movex(s, spd);
+					movex(s, spd, B_TRUE);
 				}
 			}
 		}
@@ -4894,16 +4897,16 @@ void dotileeffects(sprite_t *s) {
 	switch (tt->id) {
 		case T_WATERRIGHT:
 			if (!ismonster(s->id) && !isfruit(s->id)) {
-				movex(s, 1.5);
+				movex(s, 1.5, B_TRUE);
 			} else if (s->id == P_PLANT) {
-				movex(s, 1.5);
+				movex(s, 1.5, B_TRUE);
 			}
 			break;
 		case T_WATERLEFT:
 			if (!ismonster(s->id) && !isfruit(s->id)) {
-				movex(s, -1.5);
+				movex(s, -1.5, B_TRUE);
 			} else if (s->id == P_PLANT) {
-				movex(s, -1.5);
+				movex(s, -1.5, B_TRUE);
 			}
 			break;
 		case T_WATERDOWN:
@@ -4924,27 +4927,38 @@ void dotileeffects(sprite_t *s) {
 		if (tt->id == T_RIGHT) {
 			if (globpowerup != PW_CLOCK) {
 				if (!ismonster(s->id) && !isfruit(s->id)) {
-					movex(s, 1.5);
+					movex(s, 1.5, B_FALSE);
 				} else if (s->id == P_PLANT) {
-					movex(s, 1.5);
+					movex(s, 1.5, B_FALSE);
 				}
 			}
 			finished = B_TRUE;
 		} else if (tt->id == T_LEFT) {
 			if (globpowerup != PW_CLOCK) {
 				if (!ismonster(s->id) && !isfruit(s->id)) {
-					movex(s, -1.5);
+					movex(s, -1.5, B_FALSE);
 				} else if (s->id == P_PLANT) {
-					movex(s, -1.5);
+					movex(s, -1.5, B_FALSE);
 				}
 			}
 			finished = B_TRUE;
-		} else if ((tt->id == T_ICE) || (tt->id == T_ICETOP)) {
+		} else if (isice(tt->id))  {
 			if (isplayer(s)) {
 				if (globpowerup != PW_CLOCK) {
 					if (!s->moved) {
-						movex(s, s->dir*s->speed);
-						s->moved = MV_ICE;
+						if (s->xs != 0) {
+							// slide along the ground
+							movex(s, s->xs, B_FALSE);
+
+							// slow down
+							if (s->xs > 0) {
+								s->xs -= ICEDECCEL;
+								if (s->xs < 0) s->xs = 0;
+							} else if (s->xs < 0) {
+								s->xs += ICEDECCEL;
+								if (s->xs > 0) s->xs = 0;
+							}
+						}
 					}
 				}
 			}
@@ -6818,6 +6832,13 @@ void dogravity(sprite_t *s) {
 			} 
 			s->falling = B_TRUE;
 
+			if (isplayer(s)) {
+				// stop ice inertia
+				if (!s->moved) {
+					s->xs = 0;
+				}
+			}
+
 			if (s->id == P_FLY) {
 				// constant speed - we are flying down, not falling
 				s->y += getspeed(s);
@@ -7231,13 +7252,14 @@ void dogravity(sprite_t *s) {
 }
 
 
-int movex(sprite_t *s,double amt) {
+int movex(sprite_t *s,double amt,int onpurpose) {
 	double newx,newy;
 	double curx,cury;
 	int tilex,tiley;
 	tiletype_t *tt,*tt2;
 	int newxoff,newgroundy;
 	int newtilex,newtiley;
+	int domove = B_FALSE;
 
 	double amtdir;
 
@@ -7260,9 +7282,11 @@ int movex(sprite_t *s,double amt) {
 		newy = cury-TILEH;
 		tt2 = gettileat(newx,newy,&newtilex,&newtiley);
 		if (tt2->solid == S_SOLID) {
+			s->xs = 0;
 			return B_TRUE;
 		}
 		if (tt2->solid == S_SLOPE && (!candoslopes(s->id))) {
+			s->xs = 0;
 			return B_TRUE;
 		}
 	}
@@ -7273,32 +7297,78 @@ int movex(sprite_t *s,double amt) {
 		newy = cury;
 		tt2 = gettileat(newx,newy,&newtilex,&newtiley);
 		if (tt2->solid == S_SOLID) {
+			s->xs = 0;
 			return B_TRUE;
 		}
 		if (tt2->solid == S_SLOPE && (!candoslopes(s->id))) {
+			s->xs = 0;
 			return B_TRUE;
 		}
 	}
 
 	/* get new position */
-	newx = curx + amt;
+
+	if (isplayer(s) && isice(tt->id) && onpurpose) {
+		double newxs;
+		// change speed
+		newxs = s->xs + (s->dir*ICEACCEL);
+		s->xs += (s->dir*ICEACCEL);
+		// don't get too fast!
+		if (newxs > getspeed(s)) newxs = getspeed(s);
+		if (newxs < -getspeed(s)) newxs = -getspeed(s);
+
+		newx = curx + newxs;
+		amt = newx - curx; 
+	} else {
+		newx = curx + amt;
+	}
+
+
+
 	newy = cury-2;
 	tt2 = gettileat(newx,newy,&newtilex,&newtiley);
 	newxoff = newx - (newtilex*TILEW);
 	newgroundy = newtiley*TILEH + tt2->lowness[newxoff];
 
 	/* new block is at least partially solid */
+	domove = B_FALSE;
 	if (tt2->solid == S_SOLID) {
+		s->xs = 0;
 		return B_TRUE;
 	} else if ((tt2->solid == S_SLOPE) && candoslopes(s->id)) { 
 		/* we can move, but need to adjust our height */
-		s->x += amt;
+		domove = B_TRUE;
 	} else {
 		/* new block is empty */
-		s->x += amt;
+		domove = B_TRUE;
 	}
 
-	s->moved = MV_WALK;
+	if (domove) {
+		if (isplayer(s) && isice(tt->id) && onpurpose) {
+			// change speed
+			s->xs += (s->dir*ICEACCEL);
+			// don't get too fast!
+			if (s->xs > getspeed(s)) s->xs = getspeed(s);
+			if (s->xs < -getspeed(s)) s->xs = -getspeed(s);
+
+			s->x += s->xs;
+			s->moved = MV_WALK;
+		} else {
+			s->x += amt;
+			s->xs = amt;
+			if (!onpurpose) {
+				if (isice(tt->id)) {
+					s->moved = MV_ICE;
+				} else {
+					s->moved = MV_WALK;
+				}
+			} else {
+				s->moved = MV_WALK;
+			}
+		}
+	} else {
+		s->xs = 0;
+	}
 
 	// rings
 	if (isplayer(s)) {
@@ -11842,14 +11912,14 @@ void doplayermovement(sprite_t *pl) {
 			if (moveok) {
 				if (keydown(pnum,KEY_RIGHT)) {
 					if (canmove(pl)) {
-						movex(pl, getspeed(pl));
+						movex(pl, getspeed(pl), B_TRUE);
 					}
 					if (canturn(pl)) {
 						pl->dir = D_RIGHT;
 					}
 				} else if (keydown(pnum,KEY_LEFT)) {
 					if (canmove(pl)) {
-						movex(pl, -getspeed(pl));
+						movex(pl, -getspeed(pl), B_TRUE);
 					}
 					if (canturn(pl)) {
 						pl->dir = D_LEFT;
@@ -12106,7 +12176,7 @@ void dointroseq(void) {
 				jump(player, D_RIGHT);
 				player->jumpspeed = 7;
 			} else if (player->falling) {
-				movex(player, getspeed(player)/2);
+				movex(player, getspeed(player)/2, B_TRUE);
 			}
 		}
 		if (player2) {
@@ -12117,7 +12187,7 @@ void dointroseq(void) {
 						jump(player2, D_LEFT);
 						player2->jumpspeed = 7;
 					} else if (player2->falling) {
-						movex(player2, -getspeed(player2)/2);
+						movex(player2, -getspeed(player2)/2, B_TRUE);
 					}
 				}
 			} else {
@@ -12125,7 +12195,7 @@ void dointroseq(void) {
 					jump(player2, D_LEFT);
 					player2->jumpspeed = 7;
 				} else if (player2->falling) {
-					movex(player2, -getspeed(player2)/2);
+					movex(player2, -getspeed(player2)/2, B_TRUE);
 				}
 			}
 		}
@@ -12148,7 +12218,7 @@ void dointroseq(void) {
 		// keep moving until we hit the ground
 		if (player) {
 			if (player->falling) {
-				movex(player, getspeed(player));
+				movex(player, getspeed(player), B_TRUE);
 				
 			}
 			if (introstate == IS_RATS2) {
@@ -12160,7 +12230,7 @@ void dointroseq(void) {
 		}
 		if (player2) {
 			if (player2->falling) {
-				movex(player2, -getspeed(player2));
+				movex(player2, -getspeed(player2), B_TRUE);
 				
 			}
 			if (introstate == IS_RATS2) {
@@ -12285,3 +12355,12 @@ int countbabies(sprite_t *s, int babytype) {
 	}
 	return numbabies;
 }
+
+int isice(int id) {
+	switch (id) {
+		case T_ICE:
+		case T_ICETOP:
+			return B_TRUE;
+	}
+	return B_FALSE;
+}
diff --git a/rc.h b/rc.h
index 56d01db..f27b096 100644
--- a/rc.h
+++ b/rc.h
@@ -12,7 +12,7 @@ void removenetting(sprite_t *s);
 void drawnetting(sprite_t *s);
 void dogravity(sprite_t *s);
 void dotileeffects(sprite_t *s);
-int movex(sprite_t *s,double amt);
+int movex(sprite_t *s,double amt,int onpurpose);
 void bouncesprite(sprite_t *s);
 int movesprite(sprite_t *s);
 int isinwater(sprite_t *s);
@@ -126,3 +126,4 @@ int addcredit(void);
 int getpnum(sprite_t *s);
 int isonplatform(double x, double y);
 int countbabies(sprite_t *s, int babytype);
+int isice(int id);