From 9db9445e9fec2ce0ab52434e50cc21f30d4ef313 Mon Sep 17 00:00:00 2001
From: madmaxoft <github@xoft.cz>
Date: Fri, 20 Jun 2014 17:10:18 +0200
Subject: Optimized Voronoi calculation.

Fixes #818.
---
 src/VoronoiMap.cpp | 49 ++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 40 insertions(+), 9 deletions(-)

(limited to 'src/VoronoiMap.cpp')

diff --git a/src/VoronoiMap.cpp b/src/VoronoiMap.cpp
index 7a36edebc..9c3ca7e65 100644
--- a/src/VoronoiMap.cpp
+++ b/src/VoronoiMap.cpp
@@ -11,7 +11,9 @@
 
 
 cVoronoiMap::cVoronoiMap(int a_Seed, int a_CellSize) :
-	m_Noise(a_Seed),
+	m_Noise1(a_Seed + 1),
+	m_Noise2(a_Seed + 2),
+	m_Noise3(a_Seed + 3),
 	m_CellSize(a_CellSize)
 {
 }
@@ -57,26 +59,25 @@ int cVoronoiMap::GetValueAt(int a_X, int a_Y, int & a_MinDist1, int & a_MinDist2
 	int CellX = a_X / m_CellSize;
 	int CellZ = a_Y / m_CellSize;
 	
+	UpdateCell(CellX, CellZ);
+	
 	// Get 5x5 neighboring cell seeds, compare distance to each. Return the value in the minumim-distance cell
 	int MinDist = m_CellSize * m_CellSize * 16;  // There has to be a cell closer than this
 	int MinDist2 = MinDist;
 	int res = 0;  // Will be overriden
-	for (int x = CellX - 2; x <= CellX + 2; x++)
+	for (int x = 0; x < 5; x++)
 	{
-		int BaseX = x * m_CellSize;
-		for (int z = CellZ - 2; z < CellZ + 2; z++)
+		for (int z = 0; z < 5; z++)
 		{
-			int OffsetX = (m_Noise.IntNoise3DInt(x, 16 * x + 32 * z, z) / 8) % m_CellSize;
-			int OffsetZ = (m_Noise.IntNoise3DInt(x, 32 * x - 16 * z, z) / 8) % m_CellSize;
-			int SeedX = BaseX + OffsetX;
-			int SeedZ = z * m_CellSize + OffsetZ;
+			int SeedX = m_SeedX[x][z];
+			int SeedZ = m_SeedZ[x][z];
 			
 			int Dist = (SeedX - a_X) * (SeedX - a_X) + (SeedZ - a_Y) * (SeedZ - a_Y);
 			if (Dist < MinDist)
 			{
 				MinDist2 = MinDist;
 				MinDist = Dist;
-				res = m_Noise.IntNoise3DInt(x, x - z + 1000, z);
+				res = m_Noise3.IntNoise2DInt(x + CellX - 2, z + CellZ - 2);
 			}
 			else if (Dist < MinDist2)
 			{
@@ -93,3 +94,33 @@ int cVoronoiMap::GetValueAt(int a_X, int a_Y, int & a_MinDist1, int & a_MinDist2
 
 
 
+
+void cVoronoiMap::UpdateCell(int a_CellX, int a_CellZ)
+{
+	// If the specified cell is currently cached, bail out:
+	if ((a_CellX == m_CurrentCellX) && (a_CellZ == m_CurrentCellZ))
+	{
+		return;
+	}
+	
+	// Update the cell cache for the new cell position:
+	int NoiseBaseX = a_CellX - 2;
+	int NoiseBaseZ = a_CellZ - 2;
+	for (int x = 0; x < 5; x++)
+	{
+		int BaseX = (NoiseBaseX + x) * m_CellSize;
+		for (int z = 0; z < 5; z++)
+		{
+			int OffsetX = (m_Noise1.IntNoise2DInt(NoiseBaseX + x, NoiseBaseZ + z) / 8) % m_CellSize;
+			int OffsetZ = (m_Noise2.IntNoise2DInt(NoiseBaseX + x, NoiseBaseZ + z) / 8) % m_CellSize;
+			m_SeedX[x][z] = BaseX + OffsetX;
+			m_SeedZ[x][z] = (NoiseBaseZ + z) * m_CellSize + OffsetZ;
+		}  // for z
+	}  // for x
+	m_CurrentCellX = a_CellX;
+	m_CurrentCellZ = a_CellZ;
+}
+
+
+
+
-- 
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