From c410a4e3325350e3d9a72b867dcef44df9136f54 Mon Sep 17 00:00:00 2001
From: Merov Linden <merov@lindenlab.com>
Date: Thu, 12 Apr 2012 20:19:56 -0700
Subject: SH-3080 : Implement the TextureReverseByteRange setting so we can
 play with that parameter

---
 indra/llimage/llimage.cpp               |  4 +++-
 indra/llimage/llimage.h                 |  4 +++-
 indra/llimage/llimagej2c.cpp            |  6 +++---
 indra/newview/app_settings/settings.xml | 11 +++++++++++
 indra/newview/llappviewer.cpp           |  2 +-
 5 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/indra/llimage/llimage.cpp b/indra/llimage/llimage.cpp
index 7f95441075..6775b005f4 100644
--- a/indra/llimage/llimage.cpp
+++ b/indra/llimage/llimage.cpp
@@ -49,12 +49,14 @@
 std::string LLImage::sLastErrorMessage;
 LLMutex* LLImage::sMutex = NULL;
 bool LLImage::sUseNewByteRange = false;
+S32  LLImage::sMinimalReverseByteRangePercent = 75;
 LLPrivateMemoryPool* LLImageBase::sPrivatePoolp = NULL ;
 
 //static
-void LLImage::initClass(bool use_new_byte_range)
+void LLImage::initClass(bool use_new_byte_range, S32 minimal_reverse_byte_range_percent)
 {
 	sUseNewByteRange = use_new_byte_range;
+    sMinimalReverseByteRangePercent = minimal_reverse_byte_range_percent;
 	sMutex = new LLMutex(NULL);
 
 	LLImageBase::createPrivatePool() ;
diff --git a/indra/llimage/llimage.h b/indra/llimage/llimage.h
index a643e4d9f5..46e6d1a901 100644
--- a/indra/llimage/llimage.h
+++ b/indra/llimage/llimage.h
@@ -92,18 +92,20 @@ typedef enum e_image_codec
 class LLImage
 {
 public:
-	static void initClass(bool use_new_byte_range = false);
+	static void initClass(bool use_new_byte_range = false, S32 minimal_reverse_byte_range_percent = 75);
 	static void cleanupClass();
 
 	static const std::string& getLastError();
 	static void setLastError(const std::string& message);
 	
 	static bool useNewByteRange() { return sUseNewByteRange; }
+    static S32  getReverseByteRangePercent() { return sMinimalReverseByteRangePercent; }
 	
 protected:
 	static LLMutex* sMutex;
 	static std::string sLastErrorMessage;
 	static bool sUseNewByteRange;
+    static S32  sMinimalReverseByteRangePercent;
 };
 
 //============================================================================
diff --git a/indra/llimage/llimagej2c.cpp b/indra/llimage/llimagej2c.cpp
index 69d261c9a6..4c5c8a9c52 100644
--- a/indra/llimage/llimagej2c.cpp
+++ b/indra/llimage/llimagej2c.cpp
@@ -289,7 +289,6 @@ S32 LLImageJ2C::calcDataSizeJ2C(S32 w, S32 h, S32 comp, S32 discard_level, F32 r
 	S32 bytes;
 	S32 new_bytes = sqrt((F32)(w*h))*(F32)(comp)*rate*1000.f/layer_factor;
 	S32 old_bytes = (S32)((F32)(w*h*comp)*rate);
-	//llinfos << "Merov debug : w = " << w << ", h = " << h << ", c = " << comp << ", r = " << rate << ", d = " << discard_level << ", l = " << nb_layers << ", old = " << old_bytes << ", new = " << new_bytes << llendl;
 	bytes = (LLImage::useNewByteRange() ? new_bytes : old_bytes);
 	bytes = llmax(bytes, calcHeaderSizeJ2C());
 	return bytes;
@@ -329,8 +328,9 @@ S32 LLImageJ2C::calcDiscardLevelBytes(S32 bytes)
 	}
 	while (1)
 	{
-		S32 bytes_needed = calcDataSize(discard_level); // virtual
-		if (bytes >= bytes_needed - (bytes_needed>>2)) // For J2c, up the res at 75% of the optimal number of bytes
+		S32 bytes_needed = calcDataSize(discard_level);
+		// Use TextureReverseByteRange percent (see settings.xml) of the optimal size to qualify as correct rendering for the given discard level
+		if (bytes >= (bytes_needed*LLImage::getReverseByteRangePercent()/100))
 		{
 			break;
 		}
diff --git a/indra/newview/app_settings/settings.xml b/indra/newview/app_settings/settings.xml
index 5fc9c5d863..eff00b257c 100755
--- a/indra/newview/app_settings/settings.xml
+++ b/indra/newview/app_settings/settings.xml
@@ -10719,6 +10719,17 @@
       <key>Value</key>
       <integer>2</integer>
     </map>
+    <key>TextureReverseByteRange</key>
+    <map>
+      <key>Comment</key>
+      <string>Minimal percent of the optimal byte range allowed to render a given discard level</string>
+      <key>Persist</key>
+      <integer>1</integer>
+      <key>Type</key>
+      <string>S32</string>
+      <key>Value</key>
+      <integer>50</integer>
+    </map>
     <key>ThrottleBandwidthKBPS</key>
     <map>
       <key>Comment</key>
diff --git a/indra/newview/llappviewer.cpp b/indra/newview/llappviewer.cpp
index 1a68d0317e..37119f4451 100644
--- a/indra/newview/llappviewer.cpp
+++ b/indra/newview/llappviewer.cpp
@@ -1947,7 +1947,7 @@ bool LLAppViewer::initThreads()
 	static const bool enable_threads = true;
 #endif
 
-	LLImage::initClass(gSavedSettings.getBOOL("TextureNewByteRange"));
+	LLImage::initClass(gSavedSettings.getBOOL("TextureNewByteRange"),gSavedSettings.getBOOL("TextureReverseByteRange"));
 
 	LLVFSThread::initClass(enable_threads && false);
 	LLLFSThread::initClass(enable_threads && false);
-- 
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