From e4ef7748753489792e86f14fa7d8bace37ef8590 Mon Sep 17 00:00:00 2001
From: Charles Krinke
Date: Sun, 27 Jul 2008 16:21:51 +0000
Subject: Mantis#1831.Thank you kindly, Francis for a patch that addresses: Not
all combinations of list order equally likely with llListRandomize()
---
.../ScriptEngine/Common/LSL_BuiltIn_Commands.cs | 24 +++++++++-----------
.../Shared/Api/Implementation/LSL_Api.cs | 26 +++++++++-------------
2 files changed, 20 insertions(+), 30 deletions(-)
(limited to 'OpenSim')
diff --git a/OpenSim/Region/ScriptEngine/Common/LSL_BuiltIn_Commands.cs b/OpenSim/Region/ScriptEngine/Common/LSL_BuiltIn_Commands.cs
index a67e7ab..684c0cb 100644
--- a/OpenSim/Region/ScriptEngine/Common/LSL_BuiltIn_Commands.cs
+++ b/OpenSim/Region/ScriptEngine/Common/LSL_BuiltIn_Commands.cs
@@ -3803,9 +3803,6 @@ namespace OpenSim.Region.ScriptEngine.Common
int chunkk;
int[] chunks;
- int index1;
- int index2;
- int tmp;
m_host.AddScriptLPS(1);
@@ -3825,18 +3822,17 @@ namespace OpenSim.Region.ScriptEngine.Common
for (int i = 0; i < chunkk; i++)
chunks[i] = i;
- for (int i = 0; i < chunkk - 1; i++)
+ // Knuth shuffle the chunkk index
+ for (int i = chunkk - 1; i >= 1; i--)
{
- // randomly select 2 chunks
- index1 = rand.Next(rand.Next(65536));
- index1 = index1%chunkk;
- index2 = rand.Next(rand.Next(65536));
- index2 = index2%chunkk;
-
- // and swap their relative positions
- tmp = chunks[index1];
- chunks[index1] = chunks[index2];
- chunks[index2] = tmp;
+ // Elect an unrandomized chunk to swap
+ int index = rand.Next(i + 1);
+ int tmp;
+
+ // and swap position with first unrandomized chunk
+ tmp = chunks[i];
+ chunks[i] = chunks[index];
+ chunks[index] = tmp;
}
// Construct the randomized list
diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
index ed9bebf..4438395 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
@@ -3736,15 +3736,11 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api
public LSL_Types.list llListRandomize(LSL_Types.list src, int stride)
{
-
LSL_Types.list result;
Random rand = new Random();
int chunkk;
int[] chunks;
- int index1;
- int index2;
- int tmp;
m_host.AddScriptLPS(1);
@@ -3764,18 +3760,17 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api
for (int i = 0; i < chunkk; i++)
chunks[i] = i;
- for (int i = 0; i < chunkk - 1; i++)
+ // Knuth shuffle the chunkk index
+ for (int i = chunkk-1; i >= 1; i--)
{
- // randomly select 2 chunks
- index1 = rand.Next(rand.Next(65536));
- index1 = index1%chunkk;
- index2 = rand.Next(rand.Next(65536));
- index2 = index2%chunkk;
-
- // and swap their relative positions
- tmp = chunks[index1];
- chunks[index1] = chunks[index2];
- chunks[index2] = tmp;
+ // Elect an unrandomized chunk to swap
+ int index = rand.Next(i+1);
+ int tmp;
+
+ // and swap position with first unrandomized chunk
+ tmp = chunks[i];
+ chunks[i] = chunks[index];
+ chunks[index] = tmp;
}
// Construct the randomized list
@@ -3797,7 +3792,6 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api
}
return result;
-
}
/// <summary>
--
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