Create new tile byte format

Track tiles now have their direction information stored in the high 4
bits of the tile byte, creating a clearer separation between the type of
tile and other persistent data.

This will make the code more managable for adding new tile types and with
the new macros and enums the code is much easier to read and understand.

3 files changed, 68 insertions, 57 deletions

diff --git a/src/level.cpp b/src/level.cpp
index 92ec208..bdff5fb 100644
--- a/src/level.cpp
+++ b/src/level.cpp
@@ -6,16 +6,15 @@ Level::Level(int width, int height, Bitmap& tileSprites)
 	: m_width(width), m_height(height), m_tileSprites(tileSprites)
 {
 	m_tiles = new uint8_t[width * height];
-	memset(m_tiles, 0, width * height);
+	memset(m_tiles, TileGround, width * height);
 }
 
 uint8_t Level::get(int x, int y)
 {
-	if (inBounds(x, y)) {
+	if (inBounds(x, y))
 		return m_tiles[x + y * m_width];
-	} else {
-		return 0;
-	}
+	else
+		return TileGround;
 }
 
 void Level::set(int x, int y, uint8_t tile)
@@ -43,24 +42,27 @@ void Level::draw(Bitmap& bitmap, int xo, int yo)
 			int tx = (x + y) % 2;
 			int ty = 0;
 
-			if (tile == NorthSouth) {
-				tx = 0;
-				ty = 2;
-			} else if (tile == EastWest) {
-				tx = 1;
-				ty = 2;
-			} else if (tile == SouthEast) {
-				tx = 0;
-				ty = 3;
-			} else if (tile == SouthWest) {
-				tx = 3;
-				ty = 3;
-			} else if (tile == NorthWest) {
-				tx = 1;
-				ty = 3;
-			} else if (tile == NorthEast) {
-				tx = 2;
-				ty = 3;
+			if (TILE_TYPE(tile) == TileTrack) {
+				uint8_t dir = TILE_DATA(tile);
+				if (dir == NorthSouth) {
+					tx = 0;
+					ty = 2;
+				} else if (dir == EastWest) {
+					tx = 1;
+					ty = 2;
+				} else if (dir == SouthEast) {
+					tx = 0;
+					ty = 3;
+				} else if (dir == SouthWest) {
+					tx = 3;
+					ty = 3;
+				} else if (dir == NorthWest) {
+					tx = 1;
+					ty = 3;
+				} else if (dir == NorthEast) {
+					tx = 2;
+					ty = 3;
+				}
 			}
 
 			bitmap.blit(m_tileSprites, xx, yy, tx * TileSize, ty * TileSize, TileSize, TileSize);
@@ -80,17 +82,17 @@ void Level::addVehicle(Train& vehicle)
 void Level::toggleTile(int x, int y)
 {
 	static const auto updateDirection = [&](int xt, int yt) {
-		if (get(xt, yt) > 0)
-			set(xt, yt, ChooseDirection(*this, xt, yt));
+		if (TILE_TYPE(get(xt, yt)) == TileTrack)
+			set(xt, yt, MAKE_TILE(TileTrack, ChooseDirection(*this, xt, yt)));
 	};
 
 	if (inBounds(x, y)) {
 		auto tile = get(x, y);
 
-		if (tile > 0)
-			tile = 0;
+		if (TILE_TYPE(tile) == TileTrack)
+			tile = TileGround;
 		else
-			tile = ChooseDirection(*this, x, y);
+			tile = MAKE_TILE(TileTrack, ChooseDirection(*this, x, y));
 
 		m_tiles[x + y * m_width] = tile;
 
@@ -101,14 +103,14 @@ void Level::toggleTile(int x, int y)
 	}
 }
 
-RailDirection ChooseDirection(Level& level, int x, int y)
+TrackDirection ChooseDirection(Level& level, int x, int y)
 {
 	if (!level.inBounds(x, y)) return NorthSouth;
 
-	bool n = level.get(x, y - 1) > 0;
-	bool e = level.get(x + 1, y) > 0;
-	bool s = level.get(x, y + 1) > 0;
-	bool w = level.get(x - 1, y) > 0;
+	bool n = TILE_TYPE(level.get(x, y - 1)) == TileTrack;
+	bool e = TILE_TYPE(level.get(x + 1, y)) == TileTrack;
+	bool s = TILE_TYPE(level.get(x, y + 1)) == TileTrack;
+	bool w = TILE_TYPE(level.get(x - 1, y)) == TileTrack;
 
 	if ((n || s) && !(e || w)) {
 		return NorthSouth;
diff --git a/src/level.h b/src/level.h
index e915da3..d24ccb4 100644
--- a/src/level.h
+++ b/src/level.h
@@ -5,8 +5,26 @@
 #include <cstring>
 #include <vector>
 
+#define TILE_TYPE(x) ((x)&0xf)
+#define TILE_DATA(x) (x >> 4 & 0xf)
+#define MAKE_TILE(t, d) ((((d) & 0xf) << 4) + ((t)&0xf))
+
 class Train;
 
+enum TileType : uint8_t {
+	TileGround,
+	TileTrack
+};
+
+enum TrackDirection : uint8_t {
+	NorthSouth,
+	EastWest,
+	SouthEast,
+	SouthWest,
+	NorthWest,
+	NorthEast,
+};
+
 class Level {
 public:
 	Level(int width, int height, Bitmap& tileSprites);
@@ -30,13 +48,4 @@ private:
 	std::vector<Train*> m_vehicles;
 };
 
-enum RailDirection {
-	NorthSouth = 1,
-	EastWest,
-	SouthEast,
-	SouthWest,
-	NorthWest,
-	NorthEast,
-};
-
-RailDirection ChooseDirection(Level& level, int x, int y);
\ No newline at end of file
+TrackDirection ChooseDirection(Level& level, int x, int y);
\ No newline at end of file
diff --git a/src/train.cpp b/src/train.cpp
index 2db57ef..7ce1c2d 100644
--- a/src/train.cpp
+++ b/src/train.cpp
@@ -10,7 +10,7 @@ void Train::update()
 		m_progress = m_next->m_progress;
 	} else {
 		auto tile = m_level.get(x, y);
-		if (tile == 0)
+		if (TILE_TYPE(tile) != TileTrack)
 			return;
 	}
 
@@ -66,24 +66,24 @@ void Train::addVehicle(Train* newTrain)
 
 void Train::findDirection()
 {
-	auto tile = m_level.get(x, y);
+	auto dir = TILE_DATA(m_level.get(x, y));
 
 	if (m_dir == North) {
-		if (tile == SouthEast) m_dir = East;
-		if (tile == SouthWest) m_dir = West;
-		if (tile == EastWest) m_dir = East;
+		if (dir == SouthEast) m_dir = East;
+		if (dir == SouthWest) m_dir = West;
+		if (dir == EastWest) m_dir = East;
 	} else if (m_dir == East) {
-		if (tile == NorthWest) m_dir = North;
-		if (tile == SouthWest) m_dir = South;
-		if (tile == NorthSouth) m_dir = South;
+		if (dir == NorthWest) m_dir = North;
+		if (dir == SouthWest) m_dir = South;
+		if (dir == NorthSouth) m_dir = South;
 	} else if (m_dir == South) {
-		if (tile == NorthEast) m_dir = East;
-		if (tile == NorthWest) m_dir = West;
-		if (tile == EastWest) m_dir = West;
+		if (dir == NorthEast) m_dir = East;
+		if (dir == NorthWest) m_dir = West;
+		if (dir == EastWest) m_dir = West;
 	} else if (m_dir == West) {
-		if (tile == NorthEast) m_dir = North;
-		if (tile == SouthEast) m_dir = South;
-		if (tile == NorthSouth) m_dir = North;
+		if (dir == NorthEast) m_dir = North;
+		if (dir == SouthEast) m_dir = South;
+		if (dir == NorthSouth) m_dir = North;
 	}
 }