- lay tyre tracks only if wheels on ground

- new SurfaceType enum

src_rebuild/Game/C/dr2roads.c

@@ -11,9 +11,9 @@
 #include "main.h"
 #include "ASM/d2mapasm.h"
 
-sdPlane default_plane = { 0, 0, 0, 0, 2048 };
+sdPlane default_plane = { SURF_CONCRETE, 0, 0, 0, 2048 };
 
-sdPlane sea_plane = { 9, 0, 16384, 0, 2048 }; // a default surface if FindSurfaceD2 fails
+sdPlane sea_plane = { SURF_DEEPWATER, 0, 16384, 0, 2048 }; // a default surface if FindSurfaceD2 fails
 
 sdPlane* GetSeaPlane()
 {

src_rebuild/Game/C/handling.c

@@ -1511,7 +1511,7 @@ void CheckCarEffects(CAR_DATA* cp, int player_id)
 	for (cnt = 0; cnt < 4; cnt++)
 	{
 		if (cp->hd.wheel[cnt].susCompression != 0)
-			wheels_on_ground = 1;
+			wheels_on_ground |= 1 << cnt;
 	}
 
 	skidsound = 0;
@@ -1523,7 +1523,7 @@ void CheckCarEffects(CAR_DATA* cp, int player_id)
 		rear_vel = ABS(cp->hd.rear_vel);
 		front_vel = ABS(cp->hd.front_vel);
 
-		if (rear_vel > 15000 || cp->wheelspin)
+		if ((wheels_on_ground & 5) && (rear_vel > 15000 || cp->wheelspin))
 		{
 			lay_down_tracks |= 1;
 
@@ -1536,7 +1536,7 @@ void CheckCarEffects(CAR_DATA* cp, int player_id)
 				skidsound = 13000;
 		}
 		
-		if (front_vel > 15000)
+		if ((wheels_on_ground & 10) && front_vel > 15000)
 		{
 			lay_down_tracks |= 2;
 		}
@@ -1667,18 +1667,21 @@ void CheckCarEffects(CAR_DATA* cp, int player_id)
 	// make tyre tracks
 	GetTyreTrackPositions(cp, player_id);
 
+#define ADD_WHEEL_TYRE_TRACK(wheelNum, trackIdx) \
+		if (wheels_on_ground & (1 << wheelNum)) { \
+			AddTyreTrack(trackIdx, tracks_and_smoke, player_id, last_track_state[player_id][trackIdx] != -1); \
+			last_track_state[player_id][trackIdx] = 1; \
+		} else \
+			last_track_state[player_id][trackIdx] = -1;
+
 	if (lay_down_tracks & 1) // rear
 	{
 #if MAX_TYRE_TRACK_WHEELS == 4
-		AddTyreTrack(0, tracks_and_smoke, player_id, last_track_state[player_id][0] != -1);
+		ADD_WHEEL_TYRE_TRACK(0, 0)
-		AddTyreTrack(2, tracks_and_smoke, player_id, last_track_state[player_id][2] != -1);
+		ADD_WHEEL_TYRE_TRACK(2, 2)
-		last_track_state[player_id][0] = 1;
-		last_track_state[player_id][2] = 1;
 #else
-		AddTyreTrack(0, tracks_and_smoke, player_id, last_track_state[player_id][0] != -1);
+		ADD_WHEEL_TYRE_TRACK(0, 0)
-		AddTyreTrack(1, tracks_and_smoke, player_id, last_track_state[player_id][1] != -1);
+		ADD_WHEEL_TYRE_TRACK(2, 1)
-		last_track_state[player_id][0] = 1;
-		last_track_state[player_id][1] = 1;
 #endif
 	}
 	else
@@ -1695,17 +1698,17 @@ void CheckCarEffects(CAR_DATA* cp, int player_id)
 #if MAX_TYRE_TRACK_WHEELS == 4
 	if (lay_down_tracks & 2) // front
 	{
-		AddTyreTrack(1, tracks_and_smoke, player_id, last_track_state[player_id][1] != -1);
+		ADD_WHEEL_TYRE_TRACK(1, 1)
-		AddTyreTrack(3, tracks_and_smoke, player_id, last_track_state[player_id][3] != -1);
+		ADD_WHEEL_TYRE_TRACK(3, 3)
-		last_track_state[player_id][1] = 1;
-		last_track_state[player_id][3] = 1;
 	}
 	else
 	{
 		last_track_state[player_id][1] = -1;
 		last_track_state[player_id][3] = -1;
 	}
-#endif 
+#endif
+
+#undef ADD_WHEEL_TYRE_TRACK
 
 	SetTyreTrackOldPositions(player_id);
 }

src_rebuild/Game/C/shadow.c

@@ -137,10 +137,10 @@ void AddTyreTrack(int wheel, int tracksAndSmoke, int player_id, int continuous_t
 		// check surface type
 		if (SurfaceDataPtr != NULL) 
 		{
-			if (SurfaceDataPtr->surface == 6) 
+			if (SurfaceDataPtr->surface == SURF_WATER)
 				return;
 
-			if (SurfaceDataPtr->surface == 4)
+			if (SurfaceDataPtr->surface == SURF_GRASS)
 			{
 				tt_p->surface = 2;
 				player[player_id].onGrass = 1;
@@ -162,10 +162,10 @@ void AddTyreTrack(int wheel, int tracksAndSmoke, int player_id, int continuous_t
 		SurfaceDataPtr = sdGetCell(newtp);
 		trackSurface = 1;
 
-		if (SurfaceDataPtr->surface == 6)
+		if (SurfaceDataPtr->surface == SURF_WATER)
 			return;
 
-		if (SurfaceDataPtr->surface == 4)
+		if (SurfaceDataPtr->surface == SURF_GRASS)
 			trackSurface = 2;
 	}
 	

src_rebuild/Game/C/wheelforces.c

@@ -253,7 +253,7 @@ void AddWheelForcesDriver1(CAR_DATA* cp, CAR_LOCALS* cl)
 		friction_coef = (newCompression * (32400 - wetness) >> 15) + 500;
 
 		if (SurfacePtr != NULL)
-			wheel->onGrass = SurfacePtr->surface == 4;
+			wheel->onGrass = SurfacePtr->surface == SURF_GRASS;
 		else
 			wheel->onGrass = 0;
 
@@ -261,10 +261,10 @@ void AddWheelForcesDriver1(CAR_DATA* cp, CAR_LOCALS* cl)
 		{
 			switch (SurfacePtr->surface)
 			{
-				case 4:
+				case SURF_GRASS:
-				case 6:
+				case SURF_WATER:
-				case 9:
+				case SURF_DEEPWATER:
-				case 11:
+				case SURF_SAND:
 					wheel->surface = 0x80;
 					break;
 				default:
@@ -277,14 +277,14 @@ void AddWheelForcesDriver1(CAR_DATA* cp, CAR_LOCALS* cl)
 
 			switch (SurfacePtr->surface)
 			{
-				case 8:
+				case SURF_ALLEY:
 					wheel->surface |= 0x2;
 					break;
-				case 6:
+				case SURF_WATER:
-				case 9:
+				case SURF_DEEPWATER:
 					wheel->surface |= 0x1;
 					break;
-				case 11:
+				case SURF_SAND:
 					wheel->surface |= 0x3;
 					break;
 			}
@@ -697,7 +697,7 @@ void StepOneCar(CAR_DATA* cp)
 				Setup_Debris((VECTOR*)&deepestPoint, &direction, 10, 0);
 			}
 
-			if (SurfacePtr && (SurfacePtr->surface != 9) && (SurfacePtr->surface != 6))
+			if (SurfacePtr && (SurfacePtr->surface != SURF_DEEPWATER) && (SurfacePtr->surface != SURF_WATER))
 			{
 				CollisionSound(GetPlayerId(cp), cp, (impulse / 6 + (impulse >> 0x1f) >> 3) - (impulse >> 0x1f), 0);
 			}

src_rebuild/Game/dr2types.h

@@ -152,12 +152,20 @@ struct DRIVER2_JUNCTION
 	u_int flags;
 };
 
+enum SurfaceType
+{
+	SURF_CONCRETE	= 0,	// concrete/paved tiles
+	SURF_GRASS		= 4,
+	SURF_WATER		= 6,
+	SURF_ALLEY		= 8,
+	SURF_DEEPWATER	= 9,
+	SURF_SAND		= 11,
+};
+
 typedef struct _sdPlane
 {
-	short surface;
+	short surface;		// also one of SurfaceTypes
-	short a;
+	short a, b, c;
-	short b;
-	short c;
 	int d;
 } sdPlane;