More aggressive tile clearing for cave corridors

Use bresenham line drawing to ensure that even
corner corridors are big enough.

The downside is that due to the way bresenham
draws lines, it could cause a lot of tiles to be cleared
if they are on the wrong diagonal.

src/cdogs/algorithms.c

@@ -36,7 +36,7 @@ typedef struct
 	// and also whether to early-terminate if the line is blocked
 	bool CheckBlockedAndEarlyTerminate;
 	bool (*IsBlocked)(void *, Vec2i);
-	void (*Draw)(void *, Vec2i);
+	void (*OnPoint)(void *, Vec2i);
 	void *data;
 } AlgoLineData;
 static bool BresenhamLine(Vec2i from, Vec2i to, AlgoLineData *data)
@@ -61,7 +61,7 @@ static bool BresenhamLine(Vec2i from, Vec2i to, AlgoLineData *data)
 		}
 		else
 		{
-			data->Draw(data->data, v);
+			data->OnPoint(data->data, v);
 		}
 		if (e2 > -d.y)
 		{
@@ -84,7 +84,7 @@ static bool BresenhamLine(Vec2i from, Vec2i to, AlgoLineData *data)
 	}
 	else
 	{
-		data->Draw(data->data, v);
+		data->OnPoint(data->data, v);
 	}
 	return true;
 }
@@ -235,8 +235,8 @@ static bool XiaolinWuDraw(
 	}
 	else
 	{
-		if (RFPART(aa) > AAFACTOR) data->Draw(data->data, a);
-		if (FPART(aa) > AAFACTOR && !isEnd) data->Draw(data->data, b);
+		if (RFPART(aa) > AAFACTOR) data->OnPoint(data->data, a);
+		if (FPART(aa) > AAFACTOR && !isEnd) data->OnPoint(data->data, b);
 	}
 	return true;
 }
@@ -263,15 +263,15 @@ void BresenhamLineDraw(Vec2i from, Vec2i to, AlgoLineDrawData *data)
 {
 	AlgoLineData bData;
 	bData.CheckBlockedAndEarlyTerminate = false;
-	bData.Draw = data->Draw;
+	bData.OnPoint = data->Draw;
 	bData.data = data->data;
 	BresenhamLine(from, to, &bData);
 }
 void XiaolinWuLineDraw(Vec2i from, Vec2i to, AlgoLineDrawData *data)
 {
 	AlgoLineData bData;
 	bData.CheckBlockedAndEarlyTerminate = false;
-	bData.Draw = data->Draw;
+	bData.OnPoint = data->Draw;
 	bData.data = data->data;
 	XiaolinWuLine(from, to, &bData);
 }

src/cdogs/map_cave.c

@@ -27,15 +27,7 @@
 */
 #include "map_cave.h"
 
-#include "actors.h"
-#include "campaigns.h"
-#include "events.h"
-#include "game_events.h"
-#include "gamedata.h"
-#include "handle_game_events.h"
-#include "log.h"
-#include "map_build.h"
-#include "net_util.h"
+#include "algorithms.h"
 
 
 static void CaveRep(Map *map, const int r1, const int r2);
@@ -304,16 +296,16 @@ static void AddCorridor(
 	IMapSet(map, end, tile);
 }
 
+static bool CheckCorridorsAroundTile(
+	const Map *map, const int corridorWidth, const Vec2i v);
 // Make sure corridors are wide enough
-static void FixValidWallTile(
-	Map *map, const int corridorWidth, unsigned short *tile,
-	const Vec2i v, const Vec2i d);
 static void FixCorridors(Map *map, const int corridorWidth)
 {
 	// Find all instances where a corridor is too narrow
-	// Do this by ensuring that each wall tile is, on all four sides, either
+	// Do this by drawing a line from each wall tile to its surrounding square
+	// area, and that this line of tiles that each wall tile is either
 	// - blocked by a neighbouring wall tile, or
-	// - is followed by at least corridorWidth floor tiles in that direction
+	// - only consists of floor tiles
 	// If not, then replace that wall with a floor tile
 	Vec2i v;
 	for (v.y = corridorWidth; v.y < map->Size.y - corridorWidth; v.y++)
@@ -327,32 +319,69 @@ static void FixCorridors(Map *map, const int corridorWidth)
 			{
 				continue;
 			}
-			// Top
-			FixValidWallTile(map, corridorWidth, tile, v, Vec2iNew(0, -1));
-			// Bottom
-			FixValidWallTile(map, corridorWidth, tile, v, Vec2iNew(0, 1));
-			// Left
-			FixValidWallTile(map, corridorWidth, tile, v, Vec2iNew(-1, 0));
-			// Right
-			FixValidWallTile(map, corridorWidth, tile, v, Vec2iNew(1, 0));
+			if (!CheckCorridorsAroundTile(map, corridorWidth, v))
+			{
+				// Corridor checks failed; replace with a floor tile
+				*tile = MAP_FLOOR;
+			}
 		}
 	}
 }
-static void FixValidWallTile(
-	Map *map, const int corridorWidth, unsigned short *tile,
-	const Vec2i v, const Vec2i d)
+typedef struct
+{
+	const Map *M;
+	int Counter;
+	bool IsFirstWall;
+	bool AreAllFloors;
+} FixCorridorOnTileData;
+static void FixCorridorOnTile(void *data, Vec2i v);
+static bool CheckCorridorsAroundTile(
+	const Map *map, const int corridorWidth, const Vec2i v)
 {
-	Vec2i v1 = Vec2iAdd(v, d);
-	if (IMapGet(map, v1) != MAP_WALL)
+	AlgoLineDrawData data;
+	data.Draw = FixCorridorOnTile;
+	FixCorridorOnTileData onTileData;
+	onTileData.M = map;
+	data.data = &onTileData;
+	Vec2i v1;
+	for (v1.y = v.y - corridorWidth; v1.y <= v.y + corridorWidth; v1.y++)
 	{
-		for (int i = 0; i < corridorWidth; i++, v1 = Vec2iAdd(v1, d))
+		for (v1.x = v.x - corridorWidth; v1.x <= v.x + corridorWidth; v1.x++)
 		{
-			if (IMapGet(map, v1) != MAP_FLOOR)
+			// only draw out to edges
+			if (v1.y != v.y - corridorWidth && v1.y != v.y + corridorWidth &&
+				v1.x != v.x - corridorWidth && v1.x != v.x + corridorWidth)
 			{
-				// Not enough spaces; replace with floor
-				*tile = MAP_FLOOR;
-				return;
+				continue;
+			}
+			onTileData.Counter = 0;
+			onTileData.IsFirstWall = false;
+			onTileData.AreAllFloors = true;
+			BresenhamLineDraw(v, v1, &data);
+			if (!onTileData.IsFirstWall && !onTileData.AreAllFloors)
+			{
+				return false;
 			}
 		}
 	}
+	return true;
+}
+static void FixCorridorOnTile(void *data, Vec2i v)
+{
+	FixCorridorOnTileData *onTileData = data;
+	if (onTileData->Counter == 1)
+	{
+		// This is the first tile after the starting tile
+		// If this tile is a wall, result is good, and we don't care about
+		// the rest of the tiles anymore
+		onTileData->IsFirstWall = IMapGet(onTileData->M, v) == MAP_WALL;
+	}
+	if (onTileData->Counter > 0)
+	{
+		if (IMapGet(onTileData->M, v) != MAP_FLOOR)
+		{
+			onTileData->AreAllFloors = false;
+		}
+	}
+	onTileData->Counter++;
 }