1 files changed, 970 insertions, 0 deletions

diff --git a/src/Generating/Caves.cpp b/src/Generating/Caves.cpp
new file mode 100644
index 000000000..4221ea187
--- /dev/null
+++ b/src/Generating/Caves.cpp
@@ -0,0 +1,970 @@
+
+// Caves.cpp
+
+// Implements the various cave structure generators:
+//   - cStructGenWormNestCaves
+//   - cStructGenDualRidgeCaves
+//   - cStructGenMarbleCaves
+//   - cStructGenNetherCaves
+
+/*
+WormNestCave generator:
+Caves are generated in "nests" - groups of tunnels generated from a single point.
+For each chunk, all the nests that could intersect it are generated.
+For each nest, first the schematic structure is generated (tunnel from ... to ..., branch, tunnel2 from ... to ...)
+Then each tunnel is randomized by inserting points in between its ends.
+Finally each tunnel is smoothed and Bresenham-3D-ed so that it is a collection of spheres with their centers next to each other.
+When the tunnels are ready, they are simply carved into the chunk, one by one.
+To optimize, each tunnel keeps track of its bounding box, so that it can be skipped for chunks that don't intersect it.
+
+MarbleCaves generator:
+For each voxel a 3D noise function is evaluated, if the value crosses a boundary, the voxel is dug out, otherwise it is kept.
+Problem with this is the amount of CPU work needed for each chunk.
+Also the overall shape of the generated holes is unsatisfactory - there are whole "sheets" of holes in the ground.
+
+DualRidgeCaves generator:
+Instead of evaluating a single noise function, two different noise functions are multiplied. This produces
+regular tunnels instead of sheets. However due to the sheer amount of CPU work needed, the noise functions need to be
+reduced in complexity in order for this generator to be useful, so the caves' shapes are "bubbly" at best.
+*/
+
+#include "Globals.h"
+#include "Caves.h"
+
+
+
+
+
+/// How many nests in each direction are generated for a given chunk. Must be an even number
+#define NEIGHBORHOOD_SIZE 8
+
+
+
+
+
+const int MIN_RADIUS = 3;
+const int MAX_RADIUS = 8;
+
+
+
+
+
+struct cCaveDefPoint
+{
+	int m_BlockX;
+	int m_BlockY;
+	int m_BlockZ;
+	int m_Radius;
+	
+	cCaveDefPoint(int a_BlockX, int a_BlockY, int a_BlockZ, int a_Radius) :
+		m_BlockX(a_BlockX),
+		m_BlockY(a_BlockY),
+		m_BlockZ(a_BlockZ),
+		m_Radius(a_Radius)
+	{
+	}
+} ;
+
+typedef std::vector<cCaveDefPoint> cCaveDefPoints;
+
+
+
+
+
+/// A single non-branching tunnel of a WormNestCave
+class cCaveTunnel
+{
+	// The bounding box, including the radii around defpoints:
+	int m_MinBlockX, m_MaxBlockX;
+	int m_MinBlockY, m_MaxBlockY;
+	int m_MinBlockZ, m_MaxBlockZ;
+	
+	/// Generates the shaping defpoints for the ravine, based on the ravine block coords and noise
+	void Randomize(cNoise & a_Noise);
+	
+	/// Refines (adds and smooths) defpoints from a_Src into a_Dst; returns false if no refinement possible (segments too short)
+	bool RefineDefPoints(const cCaveDefPoints & a_Src, cCaveDefPoints & a_Dst);
+	
+	/// Does rounds of smoothing, two passes of RefineDefPoints(), as long as they return true
+	void Smooth(void);
+	
+	/// Linearly interpolates the points so that the maximum distance between two neighbors is max 1 block
+	void FinishLinear(void);
+	
+	/// Calculates the bounding box of the points present
+	void CalcBoundingBox(void);
+	
+public:
+	cCaveDefPoints m_Points;
+
+	cCaveTunnel(
+		int a_BlockStartX, int a_BlockStartY, int a_BlockStartZ, int a_StartRadius,
+		int a_BlockEndX,   int a_BlockEndY,   int a_BlockEndZ,   int a_EndRadius,
+		cNoise & a_Noise
+	);
+	
+	/// Carves the tunnel into the chunk specified
+	void ProcessChunk(
+		int a_ChunkX, int a_ChunkZ, 
+		cChunkDef::BlockTypes & a_BlockTypes, 
+		cChunkDef::HeightMap & a_HeightMap
+	);
+	
+	#ifdef _DEBUG
+	AString ExportAsSVG(int a_Color, int a_OffsetX, int a_OffsetZ) const;
+	#endif  // _DEBUG
+} ;
+
+typedef std::vector<cCaveTunnel *> cCaveTunnels;
+
+
+
+
+
+/// A collection of connected tunnels, possibly branching.
+class cStructGenWormNestCaves::cCaveSystem
+{
+public:
+	// The generating block position; is read directly in cStructGenWormNestCaves::GetCavesForChunk()
+	int m_BlockX;
+	int m_BlockZ;
+	
+	cCaveSystem(int a_BlockX, int a_BlockZ, int a_MaxOffset, int a_Size, cNoise & a_Noise);
+	~cCaveSystem();
+	
+	/// Carves the cave system into the chunk specified
+	void ProcessChunk(
+		int a_ChunkX, int a_ChunkZ, 
+		cChunkDef::BlockTypes & a_BlockTypes, 
+		cChunkDef::HeightMap & a_HeightMap
+	);
+	
+	#ifdef _DEBUG
+	AString ExportAsSVG(int a_Color, int a_OffsetX, int a_OffsetZ) const;
+	#endif  // _DEBUG
+
+protected:
+	int m_Size;
+	cCaveTunnels m_Tunnels;
+	
+	void Clear(void);
+
+	/// Generates a_Segment successive tunnels, with possible branches. Generates the same output for the same [x, y, z, a_Segments]
+	void GenerateTunnelsFromPoint(
+		int a_OriginX, int a_OriginY, int a_OriginZ, 
+		cNoise & a_Noise, int a_Segments
+	);
+	
+	/// Returns a radius based on the location provided.
+	int GetRadius(cNoise & a_Noise, int a_OriginX, int a_OriginY, int a_OriginZ);
+} ;
+
+
+
+
+
+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+// cCaveTunnel:
+
+cCaveTunnel::cCaveTunnel(
+	int a_BlockStartX, int a_BlockStartY, int a_BlockStartZ, int a_StartRadius,
+	int a_BlockEndX,   int a_BlockEndY,   int a_BlockEndZ,   int a_EndRadius,
+	cNoise & a_Noise
+)
+{
+	m_Points.push_back(cCaveDefPoint(a_BlockStartX, a_BlockStartY, a_BlockStartZ, a_StartRadius));
+	m_Points.push_back(cCaveDefPoint(a_BlockEndX,   a_BlockEndY,   a_BlockEndZ,   a_EndRadius));
+	
+	if ((a_BlockStartY <= 0) && (a_BlockEndY <= 0))
+	{
+		// Don't bother detailing this cave, it's under the world anyway
+		return;
+	}
+	
+	Randomize(a_Noise);
+	Smooth();
+	
+	// We know that the linear finishing won't affect the bounding box, so let's calculate it now, as we have less data:
+	CalcBoundingBox();
+	
+	FinishLinear();
+}
+
+
+
+
+
+void cCaveTunnel::Randomize(cNoise & a_Noise)
+{
+	// Repeat 4 times:
+	for (int i = 0; i < 4; i++)
+	{
+		// For each already present point, insert a point in between it and its predecessor, shifted randomly.
+		int PrevX = m_Points.front().m_BlockX;
+		int PrevY = m_Points.front().m_BlockY;
+		int PrevZ = m_Points.front().m_BlockZ;
+		int PrevR = m_Points.front().m_Radius;
+		cCaveDefPoints Pts;
+		Pts.reserve(m_Points.size() * 2 + 1);
+		Pts.push_back(m_Points.front());
+		for (cCaveDefPoints::const_iterator itr = m_Points.begin() + 1, end = m_Points.end(); itr != end; ++itr)
+		{
+			int Random = a_Noise.IntNoise3DInt(PrevX, PrevY, PrevZ + i) / 11;
+			int len = (PrevX - itr->m_BlockX) * (PrevX - itr->m_BlockX);
+			len += (PrevY - itr->m_BlockY) * (PrevY - itr->m_BlockY);
+			len += (PrevZ - itr->m_BlockZ) * (PrevZ - itr->m_BlockZ);
+			len = 3 * (int)sqrt((double)len) / 4;
+			int Rad = std::min(MAX_RADIUS, std::max(MIN_RADIUS, (PrevR + itr->m_Radius) / 2 + (Random % 3) - 1));
+			Random /= 4;
+			int x = (itr->m_BlockX + PrevX) / 2 + (Random % (len + 1) - len / 2);
+			Random /= 256;
+			int y = (itr->m_BlockY + PrevY) / 2 + (Random % (len / 2 + 1) - len / 4);
+			Random /= 256;
+			int z = (itr->m_BlockZ + PrevZ) / 2 + (Random % (len + 1) - len / 2);
+			Pts.push_back(cCaveDefPoint(x, y, z, Rad));
+			Pts.push_back(*itr);
+			PrevX = itr->m_BlockX;
+			PrevY = itr->m_BlockY;
+			PrevZ = itr->m_BlockZ;
+			PrevR = itr->m_Radius;
+		}
+		std::swap(Pts, m_Points);
+	}
+}
+
+
+
+
+
+bool cCaveTunnel::RefineDefPoints(const cCaveDefPoints & a_Src, cCaveDefPoints & a_Dst)
+{
+	// Smoothing: for each line segment, add points on its 1/4 lengths
+	bool res = false;
+	int Num = a_Src.size() - 2;  // this many intermediary points
+	a_Dst.clear();
+	a_Dst.reserve(Num * 2 + 2);
+	cCaveDefPoints::const_iterator itr = a_Src.begin() + 1;
+	a_Dst.push_back(a_Src.front());
+	int PrevX = a_Src.front().m_BlockX;
+	int PrevY = a_Src.front().m_BlockY;
+	int PrevZ = a_Src.front().m_BlockZ;
+	int PrevR = a_Src.front().m_Radius;
+	for (int i = 0; i <= Num; ++i, ++itr)
+	{
+		int dx = itr->m_BlockX - PrevX;
+		int dy = itr->m_BlockY - PrevY;
+		int dz = itr->m_BlockZ - PrevZ;
+		if (abs(dx) + abs(dz) + abs(dy) < 6)
+		{
+			// Too short a segment to smooth-subdivide into quarters
+			PrevX = itr->m_BlockX;
+			PrevY = itr->m_BlockY;
+			PrevZ = itr->m_BlockZ;
+			PrevR = itr->m_Radius;
+			continue;
+		}
+		int dr = itr->m_Radius - PrevR;
+		int Rad1 = std::max(PrevR + 1 * dr / 4, 1);
+		int Rad2 = std::max(PrevR + 3 * dr / 4, 1);
+		a_Dst.push_back(cCaveDefPoint(PrevX + 1 * dx / 4, PrevY + 1 * dy / 4, PrevZ + 1 * dz / 4, Rad1));
+		a_Dst.push_back(cCaveDefPoint(PrevX + 3 * dx / 4, PrevY + 3 * dy / 4, PrevZ + 3 * dz / 4, Rad2));
+		PrevX = itr->m_BlockX;
+		PrevY = itr->m_BlockY;
+		PrevZ = itr->m_BlockZ;
+		PrevR = itr->m_Radius;
+		res = true;
+	}
+	a_Dst.push_back(a_Src.back());
+	return res && (a_Src.size() < a_Dst.size());
+}
+
+
+
+
+
+void cCaveTunnel::Smooth(void)
+{
+	cCaveDefPoints Pts;
+	while (true)
+	{
+		if (!RefineDefPoints(m_Points, Pts))
+		{
+			std::swap(Pts, m_Points);
+			return;
+		}
+		if (!RefineDefPoints(Pts, m_Points))
+		{
+			return;
+		}
+	}
+}
+
+
+
+
+
+void cCaveTunnel::FinishLinear(void)
+{
+	// For each segment, use Bresenham's 3D line algorithm to draw a "line" of defpoints
+	cCaveDefPoints Pts;
+	std::swap(Pts, m_Points);
+	
+	m_Points.reserve(Pts.size() * 3);
+	int PrevX = Pts.front().m_BlockX;
+	int PrevY = Pts.front().m_BlockY;
+	int PrevZ = Pts.front().m_BlockZ;
+	for (cCaveDefPoints::const_iterator itr = Pts.begin() + 1, end = Pts.end(); itr != end; ++itr)
+	{
+		int x1 = itr->m_BlockX;
+		int y1 = itr->m_BlockY;
+		int z1 = itr->m_BlockZ;
+		int dx = abs(x1 - PrevX);
+		int dy = abs(y1 - PrevY);
+		int dz = abs(z1 - PrevZ);
+		int sx = (PrevX < x1) ? 1 : -1;
+		int sy = (PrevY < y1) ? 1 : -1;
+		int sz = (PrevZ < z1) ? 1 : -1;
+		int err = dx - dz;
+		int R = itr->m_Radius;
+
+		if (dx >= std::max(dy, dz))  // x dominant
+		{
+			int yd = dy - dx / 2;
+			int zd = dz - dx / 2;
+
+			while (true)
+			{
+				m_Points.push_back(cCaveDefPoint(PrevX, PrevY, PrevZ, R));
+
+				if (PrevX == x1)
+				{
+					break;
+				}
+
+				if (yd >= 0)  // move along y
+				{
+					PrevY += sy;
+					yd -= dx;
+				}
+
+				if (zd >= 0)  // move along z
+				{
+					PrevZ += sz;
+					zd -= dx;
+				}
+
+				// move along x
+				PrevX  += sx;
+				yd += dy;
+				zd += dz;
+			}
+		}
+		else if (dy >= std::max(dx, dz))  // y dominant
+		{
+			int xd = dx - dy / 2;
+			int zd = dz - dy / 2;
+
+			while (true)
+			{
+				m_Points.push_back(cCaveDefPoint(PrevX, PrevY, PrevZ, R));
+
+				if (PrevY == y1)
+				{
+					break;
+				}
+
+				if (xd >= 0)  // move along x
+				{
+					PrevX += sx;
+					xd -= dy;
+				}
+
+				if (zd >= 0)  // move along z
+				{
+					PrevZ += sz;
+					zd -= dy;
+				}
+
+				// move along y
+				PrevY += sy;
+				xd += dx;
+				zd += dz;
+			}
+		}
+		else
+		{
+			// z dominant
+			ASSERT(dz >= std::max(dx, dy));
+			int xd = dx - dz / 2;
+			int yd = dy - dz / 2;
+
+			while (true)
+			{
+				m_Points.push_back(cCaveDefPoint(PrevX, PrevY, PrevZ, R));
+
+				if (PrevZ == z1)
+				{
+					break;
+				}
+
+				if (xd >= 0)  // move along x
+				{
+					PrevX += sx;
+					xd -= dz;
+				}
+
+				if (yd >= 0)  // move along y
+				{
+					PrevY += sy;
+					yd -= dz;
+				}
+				
+				// move along z
+				PrevZ += sz;
+				xd += dx;
+				yd += dy;
+			}
+		}  // if (which dimension is dominant)
+	}  // for itr
+}
+
+
+
+
+
+void cCaveTunnel::CalcBoundingBox(void)
+{
+	m_MinBlockX = m_MaxBlockX = m_Points.front().m_BlockX;
+	m_MinBlockY = m_MaxBlockY = m_Points.front().m_BlockY;
+	m_MinBlockZ = m_MaxBlockZ = m_Points.front().m_BlockZ;
+	for (cCaveDefPoints::const_iterator itr = m_Points.begin() + 1, end = m_Points.end(); itr != end; ++itr)
+	{
+		m_MinBlockX = std::min(m_MinBlockX, itr->m_BlockX - itr->m_Radius);
+		m_MaxBlockX = std::max(m_MaxBlockX, itr->m_BlockX + itr->m_Radius);
+		m_MinBlockY = std::min(m_MinBlockY, itr->m_BlockY - itr->m_Radius);
+		m_MaxBlockY = std::max(m_MaxBlockY, itr->m_BlockY + itr->m_Radius);
+		m_MinBlockZ = std::min(m_MinBlockZ, itr->m_BlockZ - itr->m_Radius);
+		m_MaxBlockZ = std::max(m_MaxBlockZ, itr->m_BlockZ + itr->m_Radius);
+	}  // for itr - m_Points[]
+}
+
+
+
+
+
+void cCaveTunnel::ProcessChunk(
+	int a_ChunkX, int a_ChunkZ, 
+	cChunkDef::BlockTypes & a_BlockTypes, 
+	cChunkDef::HeightMap & a_HeightMap
+)
+{
+	int BaseX = a_ChunkX * cChunkDef::Width;
+	int BaseZ = a_ChunkZ * cChunkDef::Width;
+	if (
+		(BaseX > m_MaxBlockX) || (BaseX + cChunkDef::Width < m_MinBlockX) ||
+		(BaseX > m_MaxBlockX) || (BaseX + cChunkDef::Width < m_MinBlockX)
+	)
+	{
+		// Tunnel does not intersect the chunk at all, bail out
+		return;
+	}
+
+	int BlockStartX = a_ChunkX * cChunkDef::Width;
+	int BlockStartZ = a_ChunkZ * cChunkDef::Width;
+	int BlockEndX = BlockStartX + cChunkDef::Width;
+	int BlockEndZ = BlockStartZ + cChunkDef::Width;
+	for (cCaveDefPoints::const_iterator itr = m_Points.begin(), end = m_Points.end(); itr != end; ++itr)
+	{
+		if (
+			(itr->m_BlockX + itr->m_Radius < BlockStartX) ||
+			(itr->m_BlockX - itr->m_Radius > BlockEndX) ||
+			(itr->m_BlockZ + itr->m_Radius < BlockStartZ) ||
+			(itr->m_BlockZ - itr->m_Radius > BlockEndZ)
+		)
+		{
+			// Cannot intersect, bail out early
+			continue;
+		}
+		
+		// Carve out a sphere around the xyz point, m_Radius in diameter; skip 3/7 off the top and bottom:
+		int DifX = itr->m_BlockX - BlockStartX;  // substitution for faster calc
+		int DifY = itr->m_BlockY;
+		int DifZ = itr->m_BlockZ - BlockStartZ;  // substitution for faster calc
+		int Bottom = std::max(itr->m_BlockY - 3 * itr->m_Radius / 7, 1);
+		int Top    = std::min(itr->m_BlockY + 3 * itr->m_Radius / 7, (int)(cChunkDef::Height));
+		int SqRad  = itr->m_Radius * itr->m_Radius;
+		for (int z = 0; z < cChunkDef::Width; z++) for (int x = 0; x < cChunkDef::Width; x++) 
+		{
+			for (int y = Bottom; y <= Top; y++)
+			{
+				int SqDist = (DifX - x) * (DifX - x) + (DifY - y) * (DifY - y) + (DifZ - z) * (DifZ - z);
+				if (4 * SqDist <= SqRad)
+				{
+					switch (cChunkDef::GetBlock(a_BlockTypes, x, y, z))
+					{
+						// Only carve out these specific block types
+						case E_BLOCK_DIRT:
+						case E_BLOCK_GRASS:
+						case E_BLOCK_STONE:
+						case E_BLOCK_COBBLESTONE:
+						case E_BLOCK_GRAVEL:
+						case E_BLOCK_SAND:
+						case E_BLOCK_SANDSTONE:
+						case E_BLOCK_NETHERRACK:
+						case E_BLOCK_COAL_ORE:
+						case E_BLOCK_IRON_ORE:
+						case E_BLOCK_GOLD_ORE:
+						case E_BLOCK_DIAMOND_ORE:
+						case E_BLOCK_REDSTONE_ORE:
+						case E_BLOCK_REDSTONE_ORE_GLOWING:
+						{
+							cChunkDef::SetBlock(a_BlockTypes, x, y, z, E_BLOCK_AIR);
+							break;
+						}
+						default: break;
+					}
+				}
+			}  // for y
+		}  // for x, z
+	}  // for itr - m_Points[]
+	
+	/*
+	#ifdef _DEBUG		
+	// For debugging purposes, outline the shape of the cave using glowstone, *after* carving the entire cave:
+	for (cCaveDefPoints::const_iterator itr = m_Points.begin(), end = m_Points.end(); itr != end; ++itr)
+	{
+		int DifX = itr->m_BlockX - BlockStartX;  // substitution for faster calc
+		int DifZ = itr->m_BlockZ - BlockStartZ;  // substitution for faster calc
+		if (
+			(DifX >= 0) && (DifX < cChunkDef::Width) &&
+			(itr->m_BlockY > 0) && (itr->m_BlockY < cChunkDef::Height) &&
+			(DifZ >= 0) && (DifZ < cChunkDef::Width)
+		)
+		{
+			cChunkDef::SetBlock(a_BlockTypes, DifX, itr->m_BlockY, DifZ, E_BLOCK_GLOWSTONE);
+		}
+	}  // for itr - m_Points[]
+	#endif  // _DEBUG
+	//*/
+}
+
+
+
+
+
+#ifdef _DEBUG
+AString cCaveTunnel::ExportAsSVG(int a_Color, int a_OffsetX, int a_OffsetZ) const
+{
+	AString SVG;
+	SVG.reserve(m_Points.size() * 20 + 200);
+  AppendPrintf(SVG, "<path style=\"fill:none;stroke:#%06x;stroke-width:1px;\"\nd=\"", a_Color);
+  char Prefix = 'M';  // The first point needs "M" prefix, all the others need "L"
+  for (cCaveDefPoints::const_iterator itr = m_Points.begin(); itr != m_Points.end(); ++itr)
+  {
+		AppendPrintf(SVG, "%c %d,%d ", Prefix, a_OffsetX + itr->m_BlockX, a_OffsetZ + itr->m_BlockZ);
+		Prefix = 'L';
+  }
+  SVG.append("\"/>\n");
+	return SVG;
+}
+#endif  // _DEBUG
+
+
+
+
+
+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+// cStructGenWormNestCaves::cCaveSystem:
+
+cStructGenWormNestCaves::cCaveSystem::cCaveSystem(int a_BlockX, int a_BlockZ, int a_MaxOffset, int a_Size, cNoise & a_Noise) :
+	m_BlockX(a_BlockX),
+	m_BlockZ(a_BlockZ),
+	m_Size(a_Size)
+{
+	int Num = 1 + a_Noise.IntNoise2DInt(a_BlockX, a_BlockZ) % 3;
+	for (int i = 0; i < Num; i++)
+	{
+		int OriginX = a_BlockX + (a_Noise.IntNoise3DInt(13 * a_BlockX, 17 * a_BlockZ, 11 * i) / 19) % a_MaxOffset;
+		int OriginZ = a_BlockZ + (a_Noise.IntNoise3DInt(17 * a_BlockX, 13 * a_BlockZ, 11 * i) / 23) % a_MaxOffset;
+		int OriginY  = 20 + (a_Noise.IntNoise3DInt(19 * a_BlockX, 13 * a_BlockZ, 11 * i) / 17) % 20;
+		
+		// Generate three branches from the origin point:
+		// The tunnels generated depend on X, Y, Z and Branches,
+		// for the same set of numbers it generates the same offsets!
+		// That's why we add a +1 to X in the third line
+		GenerateTunnelsFromPoint(OriginX,     OriginY, OriginZ, a_Noise, 3);
+		GenerateTunnelsFromPoint(OriginX,     OriginY, OriginZ, a_Noise, 2);
+		GenerateTunnelsFromPoint(OriginX + 1, OriginY, OriginZ, a_Noise, 3);
+	}
+}
+
+
+
+
+
+cStructGenWormNestCaves::cCaveSystem::~cCaveSystem()
+{
+	Clear();
+}
+
+
+
+
+
+
+void cStructGenWormNestCaves::cCaveSystem::ProcessChunk(
+	int a_ChunkX, int a_ChunkZ, 
+	cChunkDef::BlockTypes & a_BlockTypes, 
+	cChunkDef::HeightMap & a_HeightMap
+)
+{
+	for (cCaveTunnels::const_iterator itr = m_Tunnels.begin(), end = m_Tunnels.end(); itr != end; ++itr)
+	{
+		(*itr)->ProcessChunk(a_ChunkX, a_ChunkZ, a_BlockTypes, a_HeightMap);
+	}  // for itr - m_Tunnels[]
+}
+
+
+
+
+
+#ifdef _DEBUG
+AString cStructGenWormNestCaves::cCaveSystem::ExportAsSVG(int a_Color, int a_OffsetX, int a_OffsetZ) const
+{
+	AString SVG;
+	SVG.reserve(512 * 1024);
+	for (cCaveTunnels::const_iterator itr = m_Tunnels.begin(), end = m_Tunnels.end(); itr != end; ++itr)
+	{
+		SVG.append((*itr)->ExportAsSVG(a_Color, a_OffsetX, a_OffsetZ));
+	}  // for itr - m_Tunnels[]
+
+	// Base point highlight:
+	AppendPrintf(SVG, "<path style=\"fill:none;stroke:#ff0000;stroke-width:1px;\"\nd=\"M %d,%d L %d,%d\"/>\n",
+		a_OffsetX + m_BlockX - 5, a_OffsetZ + m_BlockZ, a_OffsetX + m_BlockX + 5, a_OffsetZ + m_BlockZ
+	);
+	AppendPrintf(SVG, "<path style=\"fill:none;stroke:#ff0000;stroke-width:1px;\"\nd=\"M %d,%d L %d,%d\"/>\n",
+		a_OffsetX + m_BlockX, a_OffsetZ + m_BlockZ - 5, a_OffsetX + m_BlockX, a_OffsetZ + m_BlockZ + 5
+	);
+	
+	// A gray line from the base point to the first point of the ravine, for identification:
+	AppendPrintf(SVG, "<path style=\"fill:none;stroke:#cfcfcf;stroke-width:1px;\"\nd=\"M %d,%d L %d,%d\"/>\n",
+		a_OffsetX + m_BlockX, a_OffsetZ + m_BlockZ, 
+		a_OffsetX + m_Tunnels.front()->m_Points.front().m_BlockX, 
+		a_OffsetZ + m_Tunnels.front()->m_Points.front().m_BlockZ
+	);
+	
+	// Offset guides:
+	if (a_OffsetX > 0)
+	{
+		AppendPrintf(SVG, "<path style=\"fill:none;stroke:#0000ff;stroke-width:1px;\"\nd=\"M %d,0 L %d,1024\"/>\n",
+			a_OffsetX, a_OffsetX
+		);
+	}
+	if (a_OffsetZ > 0)
+	{
+		AppendPrintf(SVG, "<path style=\"fill:none;stroke:#0000ff;stroke-width:1px;\"\nd=\"M 0,%d L 1024,%d\"/>\n",
+			a_OffsetZ, a_OffsetZ
+		);
+	}
+	
+	return SVG;
+}
+#endif  // _DEBUG
+
+
+
+
+
+void cStructGenWormNestCaves::cCaveSystem::Clear(void)
+{
+	for (cCaveTunnels::const_iterator itr = m_Tunnels.begin(), end = m_Tunnels.end(); itr != end; ++itr)
+	{
+		delete *itr;
+	}
+	m_Tunnels.clear();
+}
+
+
+
+
+
+void cStructGenWormNestCaves::cCaveSystem::GenerateTunnelsFromPoint(
+	int a_OriginX, int a_OriginY, int a_OriginZ, 
+	cNoise & a_Noise, int a_NumSegments
+)
+{
+	int DoubleSize = m_Size * 2;
+	int Radius = GetRadius(a_Noise, a_OriginX + a_OriginY, a_OriginY + a_OriginZ, a_OriginZ + a_OriginX);
+	for (int i = a_NumSegments - 1; i >= 0; --i)
+	{
+		int EndX = a_OriginX + (((a_Noise.IntNoise3DInt(a_OriginX, a_OriginY, a_OriginZ + 11 * a_NumSegments) / 7) % DoubleSize) - m_Size) / 2;
+		int EndY = a_OriginY + (((a_Noise.IntNoise3DInt(a_OriginY, 13 * a_NumSegments, a_OriginZ + a_OriginX) / 7) % DoubleSize) - m_Size) / 4;
+		int EndZ = a_OriginZ + (((a_Noise.IntNoise3DInt(a_OriginZ + 17 * a_NumSegments, a_OriginX, a_OriginY) / 7) % DoubleSize) - m_Size) / 2;
+		int EndR = GetRadius(a_Noise, a_OriginX + 7 * i, a_OriginY + 11 * i, a_OriginZ + a_OriginX);
+		m_Tunnels.push_back(new cCaveTunnel(a_OriginX, a_OriginY, a_OriginZ, Radius, EndX, EndY, EndZ, EndR, a_Noise));
+		GenerateTunnelsFromPoint(EndX, EndY, EndZ, a_Noise, i);
+		a_OriginX = EndX;
+		a_OriginY = EndY;
+		a_OriginZ = EndZ;
+		Radius = EndR;
+	}  // for i - a_NumSegments
+}
+
+
+
+
+
+int cStructGenWormNestCaves::cCaveSystem::GetRadius(cNoise & a_Noise, int a_OriginX, int a_OriginY, int a_OriginZ)
+{
+	// Instead of a flat distribution noise function, we need to shape it, so that most caves are smallish and only a few select are large
+	int rnd = a_Noise.IntNoise3DInt(a_OriginX, a_OriginY, a_OriginZ) / 11;
+	/*
+	// Not good enough:
+	// The algorithm of choice: emulate gauss-distribution noise by adding 3 flat noises, then fold it in half using absolute value.
+	// To save on processing, use one random value and extract 3 bytes to be separately added as the gaussian noise
+	int sum = (rnd & 0xff) + ((rnd >> 8) & 0xff) + ((rnd >> 16) & 0xff);
+	// sum is now a gaussian-distribution noise within [0 .. 767], with center at 384.
+	// We want mapping 384 -> 3, 0 -> 19, 768 -> 19, so divide by 24 to get [0 .. 31] with center at 16, then use abs() to fold around the center
+	int res = 3 + abs((sum / 24) - 16);
+	*/
+	
+	// Algorithm of choice: random value in the range of zero to random value - heavily towards zero
+	int res = MIN_RADIUS + (rnd >> 8) % ((rnd % (MAX_RADIUS - MIN_RADIUS)) + 1);
+	return res;
+}
+
+
+
+
+
+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+// cStructGenWormNestCaves:
+
+cStructGenWormNestCaves::~cStructGenWormNestCaves()
+{
+	ClearCache();
+}
+
+
+
+
+
+void cStructGenWormNestCaves::ClearCache(void)
+{
+	for (cCaveSystems::const_iterator itr = m_Cache.begin(), end = m_Cache.end(); itr != end; ++itr)
+	{
+		delete *itr;
+	}  // for itr - m_Cache[]
+	m_Cache.clear();
+}
+
+
+
+
+
+void cStructGenWormNestCaves::GenStructures(cChunkDesc & a_ChunkDesc)
+{
+	int ChunkX = a_ChunkDesc.GetChunkX();
+	int ChunkZ = a_ChunkDesc.GetChunkZ();
+	cCaveSystems Caves;
+	GetCavesForChunk(ChunkX, ChunkZ, Caves);
+	for (cCaveSystems::const_iterator itr = Caves.begin(); itr != Caves.end(); ++itr)
+	{
+		(*itr)->ProcessChunk(ChunkX, ChunkZ, a_ChunkDesc.GetBlockTypes(), a_ChunkDesc.GetHeightMap());
+	}  // for itr - Caves[]
+}
+
+
+
+
+
+void cStructGenWormNestCaves::GetCavesForChunk(int a_ChunkX, int a_ChunkZ, cStructGenWormNestCaves::cCaveSystems & a_Caves)
+{
+	int BaseX = a_ChunkX * cChunkDef::Width / m_Grid;
+	int BaseZ = a_ChunkZ * cChunkDef::Width / m_Grid;
+	if (BaseX < 0)
+	{
+		--BaseX;
+	}
+	if (BaseZ < 0)
+	{
+		--BaseZ;
+	}
+	BaseX -= NEIGHBORHOOD_SIZE / 2;
+	BaseZ -= NEIGHBORHOOD_SIZE / 2;
+
+	// Walk the cache, move each cave system that we want into a_Caves:
+	int StartX = BaseX * m_Grid;
+	int EndX = (BaseX + NEIGHBORHOOD_SIZE + 1) * m_Grid;
+	int StartZ = BaseZ * m_Grid;
+	int EndZ = (BaseZ + NEIGHBORHOOD_SIZE + 1) * m_Grid;
+	for (cCaveSystems::iterator itr = m_Cache.begin(), end = m_Cache.end(); itr != end;)
+	{
+		if (
+			((*itr)->m_BlockX >= StartX) && ((*itr)->m_BlockX < EndX) &&
+			((*itr)->m_BlockZ >= StartZ) && ((*itr)->m_BlockZ < EndZ)
+		)
+		{
+			// want
+			a_Caves.push_back(*itr);
+			itr = m_Cache.erase(itr);
+		}
+		else
+		{
+			// don't want
+			++itr;
+		}
+	}  // for itr - m_Cache[]
+	
+	for (int x = 0; x < NEIGHBORHOOD_SIZE; x++)
+	{
+		int RealX = (BaseX + x) * m_Grid;
+		for (int z = 0; z < NEIGHBORHOOD_SIZE; z++)
+		{
+			int RealZ = (BaseZ + z) * m_Grid;
+			bool Found = false;
+			for (cCaveSystems::const_iterator itr = a_Caves.begin(), end = a_Caves.end(); itr != end; ++itr)
+			{
+				if (((*itr)->m_BlockX == RealX) && ((*itr)->m_BlockZ == RealZ))
+				{
+					Found = true;
+					break;
+				}
+			}
+			if (!Found)
+			{
+				a_Caves.push_back(new cCaveSystem(RealX, RealZ, m_MaxOffset, m_Size, m_Noise));
+			}
+		}
+	}
+	
+	// Copy a_Caves into m_Cache to the beginning:
+	cCaveSystems CavesCopy(a_Caves);
+	m_Cache.splice(m_Cache.begin(), CavesCopy, CavesCopy.begin(), CavesCopy.end());
+	
+	// Trim the cache if it's too long:
+	if (m_Cache.size() > 100)
+	{
+		cCaveSystems::iterator itr = m_Cache.begin();
+		std::advance(itr, 100);
+		for (cCaveSystems::iterator end = m_Cache.end(); itr != end; ++itr)
+		{
+			delete *itr;
+		}
+		itr = m_Cache.begin();
+		std::advance(itr, 100);
+		m_Cache.erase(itr, m_Cache.end());
+	}
+	
+	/*
+	// Uncomment this block for debugging the caves' shapes in 2D using an SVG export
+	#ifdef _DEBUG
+	AString SVG;
+	SVG.append("<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\"?>\n<svg xmlns=\"http://www.w3.org/2000/svg\" width=\"1024\" height = \"1024\">\n");
+	SVG.reserve(2 * 1024 * 1024);
+	for (cCaveSystems::const_iterator itr = a_Caves.begin(), end = a_Caves.end(); itr != end; ++itr)
+	{
+		int Color = 0x10 * abs((*itr)->m_BlockX / m_Grid);
+		Color |= 0x1000 * abs((*itr)->m_BlockZ / m_Grid);
+		SVG.append((*itr)->ExportAsSVG(Color, 512, 512));
+	}
+	SVG.append("</svg>\n");
+	
+	AString fnam;
+	Printf(fnam, "wnc\\%03d_%03d.svg", a_ChunkX, a_ChunkZ);
+	cFile File(fnam, cFile::fmWrite);
+	File.Write(SVG.c_str(), SVG.size());
+	#endif  // _DEBUG
+	//*/
+}
+
+
+
+
+
+
+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+// cStructGenMarbleCaves:
+
+static float GetMarbleNoise( float x, float y, float z, cNoise & a_Noise )
+{
+	static const float PI_2 = 1.57079633f;
+	float oct1 = (a_Noise.CubicNoise3D(x * 0.1f, y * 0.1f, z * 0.1f )) * 4;
+
+	oct1 = oct1 * oct1 * oct1;
+	if (oct1 < 0.f)  oct1 = PI_2;
+	if (oct1 > PI_2) oct1 = PI_2;
+
+	return oct1;
+}
+
+
+
+
+
+void cStructGenMarbleCaves::GenStructures(cChunkDesc & a_ChunkDesc)
+{
+	cNoise Noise(m_Seed);
+	for (int z = 0; z < cChunkDef::Width; z++) 
+	{
+		const float zz = (float)(a_ChunkDesc.GetChunkZ() * cChunkDef::Width + z);
+		for (int x = 0; x < cChunkDef::Width; x++)
+		{
+			const float xx = (float)(a_ChunkDesc.GetChunkX() * cChunkDef::Width + x);
+			
+			int Top = a_ChunkDesc.GetHeight(x, z);
+			for (int y = 1; y < Top; ++y )
+			{
+				if (a_ChunkDesc.GetBlockType(x, y, z) != E_BLOCK_STONE)
+				{
+					continue;
+				}
+
+				const float yy = (float)y;
+				const float WaveNoise = 1;
+				if (cosf(GetMarbleNoise(xx, yy * 0.5f, zz, Noise)) * fabs(cosf(yy * 0.2f + WaveNoise * 2) * 0.75f + WaveNoise) > 0.0005f)
+				{
+					a_ChunkDesc.SetBlockType(x, y, z, E_BLOCK_AIR);
+				}
+			}  // for y
+		}  // for x
+	}  // for z
+}
+
+
+
+
+
+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+// cStructGenDualRidgeCaves:
+
+void cStructGenDualRidgeCaves::GenStructures(cChunkDesc & a_ChunkDesc)
+{
+	for (int z = 0; z < cChunkDef::Width; z++) 
+	{
+		const float zz = (float)(a_ChunkDesc.GetChunkZ() * cChunkDef::Width + z) / 10;
+		for (int x = 0; x < cChunkDef::Width; x++)
+		{
+			const float xx = (float)(a_ChunkDesc.GetChunkX() * cChunkDef::Width + x) / 10;
+			
+			int Top = a_ChunkDesc.GetHeight(x, z);
+			for (int y = 1; y <= Top; ++y)
+			{
+				const float yy = (float)y / 10;
+				const float WaveNoise = 1;
+				float n1 = m_Noise1.CubicNoise3D(xx, yy, zz);
+				float n2 = m_Noise2.CubicNoise3D(xx, yy, zz);
+				float n3 = m_Noise1.CubicNoise3D(xx * 4, yy * 4, zz * 4) / 4;
+				float n4 = m_Noise2.CubicNoise3D(xx * 4, yy * 4, zz * 4) / 4;
+				if ((abs(n1 + n3) * abs(n2 + n4)) > m_Threshold)
+				{
+					a_ChunkDesc.SetBlockType(x, y, z, E_BLOCK_AIR);
+				}
+			}  // for y
+		}  // for x
+	}  // for z
+}
+
+
+
+