From 5622ad4b5efdba60db4bcfaf03ba358c569064f6 Mon Sep 17 00:00:00 2001
From: tron <tron@openttd.org>
Date: Sun, 7 May 2006 07:55:05 +0000
Subject: (svn r4765) Add GetTileMaxZ(), which returns the height of the
 highest corner of a tile, and use it to simplify the code in a few places

---
 industry_cmd.c     | 14 +++++---------
 landscape.c        |  3 +--
 tile.c             | 17 +++++++++++++++++
 tile.h             |  1 +
 train_cmd.c        |  9 ++-------
 tunnelbridge_cmd.c |  4 +---
 6 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/industry_cmd.c b/industry_cmd.c
index 1a4c96209..bad47ae6d 100644
--- a/industry_cmd.c
+++ b/industry_cmd.c
@@ -535,15 +535,11 @@ static void AnimateTile_Industry(TileIndex tile)
 
 static void CreateIndustryEffectSmoke(TileIndex tile)
 {
-	Slope tileh;
-	uint x;
-	uint y;
-	uint z;
-
-	tileh = GetTileSlope(tile, &z);
-	x = TileX(tile) * TILE_SIZE;
-	y = TileY(tile) * TILE_SIZE;
-	CreateEffectVehicle(x + 15, y + 14, z + 59 + (tileh != SLOPE_FLAT ? TILE_HEIGHT : 0), EV_CHIMNEY_SMOKE);
+	uint x = TileX(tile) * TILE_SIZE;
+	uint y = TileY(tile) * TILE_SIZE;
+	uint z = GetTileMaxZ(tile);
+
+	CreateEffectVehicle(x + 15, y + 14, z + 59, EV_CHIMNEY_SMOKE);
 }
 
 static void MakeIndustryTileBigger(TileIndex tile)
diff --git a/landscape.c b/landscape.c
index 53c72dfaf..cc044eab2 100644
--- a/landscape.c
+++ b/landscape.c
@@ -396,10 +396,9 @@ void InitializeLandscape(void)
 void ConvertGroundTilesIntoWaterTiles(void)
 {
 	TileIndex tile = 0;
-	uint h;
 
 	for (tile = 0; tile < MapSize(); ++tile) {
-		if (IsTileType(tile, MP_CLEAR) && GetTileSlope(tile, &h) == SLOPE_FLAT && h == 0) {
+		if (IsTileType(tile, MP_CLEAR) && GetTileMaxZ(tile) == 0) {
 			MakeWater(tile);
 		}
 	}
diff --git a/tile.c b/tile.c
index 36df4c542..98fb5f0bd 100644
--- a/tile.c
+++ b/tile.c
@@ -56,3 +56,20 @@ uint GetTileZ(TileIndex tile)
 	GetTileSlope(tile, &h);
 	return h;
 }
+
+
+uint GetTileMaxZ(TileIndex t)
+{
+	uint max;
+	uint h;
+
+	h = TileHeight(t);
+	max = h;
+	h = TileHeight(t + TileDiffXY(1, 0));
+	if (h > max) max = h;
+	h = TileHeight(t + TileDiffXY(0, 1));
+	if (h > max) max = h;
+	h = TileHeight(t + TileDiffXY(1, 1));
+	if (h > max) max = h;
+	return max * 8;
+}
diff --git a/tile.h b/tile.h
index cb51208e3..ebb1bb89a 100644
--- a/tile.h
+++ b/tile.h
@@ -30,6 +30,7 @@ typedef enum TropicZones {
 Slope GetTileh(uint n, uint w, uint e, uint s, uint *h);
 Slope GetTileSlope(TileIndex tile, uint *h);
 uint GetTileZ(TileIndex tile);
+uint GetTileMaxZ(TileIndex tile);
 
 static inline bool CorrectZ(Slope tileh)
 {
diff --git a/train_cmd.c b/train_cmd.c
index a4ae5d61e..a9d5950b1 100644
--- a/train_cmd.c
+++ b/train_cmd.c
@@ -2623,13 +2623,8 @@ static bool CheckCompatibleRail(const Vehicle *v, TileIndex tile)
 
 		case MP_TUNNELBRIDGE:
 			if (IsBridge(tile) && IsBridgeMiddle(tile)) {
-				uint height;
-				Slope tileh = GetTileSlope(tile, &height);
-
-				// correct Z position of a train going under a bridge on slopes
-				if (tileh != SLOPE_FLAT) height += TILE_HEIGHT;
-
-				if (v->z_pos > height) return true; // train is going over bridge
+				// is train going over the bridge?
+				if (v->z_pos > GetTileMaxZ(tile)) return true;
 			}
 			break;
 
diff --git a/tunnelbridge_cmd.c b/tunnelbridge_cmd.c
index 503616e67..aca77e9e1 100644
--- a/tunnelbridge_cmd.c
+++ b/tunnelbridge_cmd.c
@@ -1357,10 +1357,8 @@ static uint32 VehicleEnter_TunnelBridge(Vehicle *v, TileIndex tile, int x, int y
 		}
 	} else if (IsBridge(tile)) { // XXX is this necessary?
 		if (v->type == VEH_Road || (v->type == VEH_Train && IsFrontEngine(v))) {
-			uint h;
+			uint h = GetTileMaxZ(tile);
 
-			// Compensate for possible foundation
-			if (GetTileSlope(tile, &h) != SLOPE_FLAT) h += TILE_HEIGHT;
 			if (IsBridgeRamp(tile) ||
 					myabs(h - v->z_pos) > 2) { // high above the ground -> on the bridge
 				/* modify speed of vehicle */
-- 
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