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* Patch from jhurliman - Implements a binary search in the LLRAW exporter which dramatically speeds up exports.

0.6.0-stable
Adam Frisby 2008-05-26 21:39:01 +00:00
parent ed717ec181
commit de06c85259
1 changed files with 44 additions and 26 deletions
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68
OpenSim/Region/Environment/Modules/World/Terrain/FileLoaders/LLRAW.cs
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@ -33,6 +33,40 @@ namespace OpenSim.Region.Environment.Modules.World.Terrain.FileLoaders
{
public class LLRAW : ITerrainLoader
{
public struct HeightmapLookupValue : IComparable<HeightmapLookupValue>
{
public int Index;
public double Value;
public HeightmapLookupValue(int index, double value)
{
Index = index;
Value = value;
}
public int CompareTo(HeightmapLookupValue val)
{
return Value.CompareTo(val.Value);
}
}
/// <summary>Lookup table to speed up terrain exports</summary>
HeightmapLookupValue[] LookupHeightTable;
public LLRAW()
{
LookupHeightTable = new HeightmapLookupValue[256 * 256];
for (int i = 0; i < 256; i++)
{
for (int j = 0; j < 256; j++)
{
LookupHeightTable[i + (j * 256)] = new HeightmapLookupValue(i + (j * 256), ((double)i * ((double)j / 127.0d)));
}
}
Array.Sort<HeightmapLookupValue>(LookupHeightTable);
}
#region ITerrainLoader Members
public ITerrainChannel LoadFile(string filename)
@ -70,37 +104,21 @@ namespace OpenSim.Region.Environment.Modules.World.Terrain.FileLoaders
FileStream s = file.Open(FileMode.CreateNew, FileAccess.Write);
BinaryWriter binStream = new BinaryWriter(s);
// Generate a smegging big lookup table to speed the operation up (it needs it)
double[] lookupHeightTable = new double[65536];
int i;
int y;
for (i = 0; i < 256; i++)
{
int j;
for (j = 0; j < 256; j++)
{
lookupHeightTable[i + (j * 256)] = (i * (j / 127.0));
}
}
// Output the calculated raw
for (y = 0; y < map.Height; y++)
for (int y = 0; y < map.Height; y++)
{
int x;
for (x = 0; x < map.Width; x++)
for (int x = 0; x < map.Width; x++)
{
double t = map[x, y];
double min = double.MaxValue;
int index = 0;
for (i = 0; i < 65536; i++)
{
if (Math.Abs(t - lookupHeightTable[i]) < min)
{
min = Math.Abs(t - lookupHeightTable[i]);
index = i;
}
}
// The lookup table is pre-sorted, so we either find an exact match or
// the next closest (smaller) match with a binary search
index = Array.BinarySearch<HeightmapLookupValue>(LookupHeightTable, new HeightmapLookupValue(0, t));
if (index < 0)
index = ~index - 1;
index = LookupHeightTable[index].Index;
byte red = (byte) (index & 0xFF);
byte green = (byte) ((index >> 8) & 0xFF);