From e49313202c759f70f6cf1113c8b53471122eb7da Mon Sep 17 00:00:00 2001
From: "madmaxoft@gmail.com"
 <madmaxoft@gmail.com@0a769ca7-a7f5-676a-18bf-c427514a06d6>
Date: Sun, 29 Jul 2012 20:15:03 +0000
Subject: DistortedVoronoi BiomeGen now uses 4x4 linear interpolation for
 distortion, 50 % speed increase in the chunk generator with a hardly
 noticeable change in biome shapes.

git-svn-id: http://mc-server.googlecode.com/svn/trunk@708 0a769ca7-a7f5-676a-18bf-c427514a06d6
---
 source/BioGen.cpp | 17 ++++++++++---
 source/cNoise.cpp | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 source/cNoise.h   | 11 +++++++++
 3 files changed, 98 insertions(+), 4 deletions(-)

diff --git a/source/BioGen.cpp b/source/BioGen.cpp
index 73529abb6..a43d995df 100644
--- a/source/BioGen.cpp
+++ b/source/BioGen.cpp
@@ -258,14 +258,25 @@ void cBioGenDistortedVoronoi::GenBiomes(int a_ChunkX, int a_ChunkZ, cChunkDef::B
 {
 	int BaseZ = cChunkDef::Width * a_ChunkZ;
 	int BaseX = cChunkDef::Width * a_ChunkX;
+	
+	// Distortions for linear interpolation:
+	int DistortX[cChunkDef::Width + 1][cChunkDef::Width + 1];
+	int DistortZ[cChunkDef::Width + 1][cChunkDef::Width + 1];
+	for (int x = 0; x <= 4; x++) for (int z = 0; z <= 4; z++)
+	{
+		Distort(BaseX + x * 4, BaseZ + z * 4, DistortX[4 * x][4 * z], DistortZ[4 * x][4 * z]);
+	}
+	
+	IntArrayLinearInterpolate2D(&DistortX[0][0], cChunkDef::Width + 1, cChunkDef::Width + 1, 4, 4);
+	IntArrayLinearInterpolate2D(&DistortZ[0][0], cChunkDef::Width + 1, cChunkDef::Width + 1, 4, 4);
+	
 	for (int z = 0; z < cChunkDef::Width; z++)
 	{
 		int AbsoluteZ = BaseZ + z;
 		for (int x = 0; x < cChunkDef::Width; x++)
 		{
-			int DistX, DistZ;
-			Distort(BaseX + x, AbsoluteZ, DistX, DistZ);
-			cChunkDef::SetBiome(a_BiomeMap, x, z, VoronoiBiome(DistX, DistZ));
+			// Distort(BaseX + x, AbsoluteZ, DistX, DistZ);
+			cChunkDef::SetBiome(a_BiomeMap, x, z, VoronoiBiome(DistortX[x][z], DistortZ[x][z]));
 		}  // for x
 	}  // for z
 }
diff --git a/source/cNoise.cpp b/source/cNoise.cpp
index 2dd26e5aa..b4e7a5752 100644
--- a/source/cNoise.cpp
+++ b/source/cNoise.cpp
@@ -183,6 +183,10 @@ float cNoise::SSE_CubicNoise2D( float a_X, float a_Y ) const
 }
 #endif
 
+
+
+
+
 /******************
  * Interpolated (and 1 smoothed) noise in 3-dimensions
  **/
@@ -216,6 +220,10 @@ float cNoise::CosineNoise3D( float a_X, float a_Y, float a_Z ) const
 	return CosineInterpolate( interp1, interp2, FracZ );
 }
 
+
+
+
+
 float cNoise::CubicNoise3D( float a_X, float a_Y, float a_Z ) const
 {
 	const int	BaseX = FAST_FLOOR( a_X );
@@ -281,6 +289,10 @@ float cNoise::CubicNoise3D( float a_X, float a_Y, float a_Z ) const
 	return CubicInterpolate( yinterp1, yinterp2, yinterp3, yinterp4, FracZ );
 }
 
+
+
+
+
 /******************
  * Private
  **/
@@ -300,6 +312,66 @@ __m128 cNoise::CubicInterpolate4( const __m128 & a_A, const __m128 & a_B, const
 }
 #endif
 
+
+
+
+
+void IntArrayLinearInterpolate2D(
+	int * a_Array, 
+	int a_SizeX, int a_SizeY,  // Dimensions of the array
+	int a_AnchorStepX, int a_AnchorStepY  // Distances between the anchor points in each direction
+)
+{
+	// First interpolate columns where the anchor points are:
+	int LastYCell = a_SizeY - a_AnchorStepY;
+	for (int y = 0; y < LastYCell; y += a_AnchorStepY)
+	{
+		int Idx = a_SizeX * y;
+		for (int x = 0; x < a_SizeX; x += a_AnchorStepX)
+		{
+			int StartValue = a_Array[Idx];
+			int EndValue   = a_Array[Idx + a_SizeX * a_AnchorStepY];
+			int Diff = EndValue - StartValue;
+			for (int CellY = 1; CellY < a_AnchorStepY; CellY++)
+			{
+				a_Array[Idx + a_SizeX * CellY] = StartValue + CellY * Diff / a_AnchorStepY;
+			}  // for CellY
+			Idx += a_AnchorStepX;
+		}  // for x
+	}  // for y
+	
+	// Now interpolate in rows, each row has values in the anchor columns
+	int LastXCell = a_SizeX - a_AnchorStepX;
+	for (int y = 0; y < a_SizeY; y++)
+	{
+		int Idx = a_SizeX * y;
+		for (int x = 0; x < LastXCell; x += a_AnchorStepX)
+		{
+			int StartValue = a_Array[Idx];
+			int EndValue   = a_Array[Idx + a_AnchorStepX];
+			int Diff = EndValue - StartValue;
+			for (int CellX = 1; CellX < a_AnchorStepX; CellX++)
+			{
+				a_Array[Idx + CellX] = StartValue + CellX * Diff / a_AnchorStepX;
+			}  // for CellY
+			Idx += a_AnchorStepX;
+		}
+	}
+}
+
+
+
+
+
+
+
+
+
+
 #if NOISE_USE_INLINE
 # include "cNoise.inc"
-#endif
\ No newline at end of file
+#endif
+
+
+
+
diff --git a/source/cNoise.h b/source/cNoise.h
index 74c2cdd02..6d0a69483 100644
--- a/source/cNoise.h
+++ b/source/cNoise.h
@@ -74,6 +74,17 @@ private:
 
 
 
+/// Linearly interpolates values in the array between the anchor points
+extern void IntArrayLinearInterpolate2D(
+	int * a_Array, 
+	int a_SizeX, int a_SizeY,  // Dimensions of the array
+	int a_AnchorStepX, int a_AnchorStepY  // Distances between the anchor points in each direction
+);
+
+
+
+
+
 #if NOISE_USE_INLINE
 # include "cNoise.inc"
 #endif
-- 
cgit v1.2.3