Merge branch 'DRTVWR-546' into DRTVWR-539

# Conflicts:
#	indra/llcommon/tests/llprocess_test.cpp
#	indra/llui/llcombobox.cpp
#	indra/llui/llcombobox.h
#	indra/newview/VIEWER_VERSION.txt
#	indra/newview/llviewertexturelist.cpp
#	indra/newview/llvovolume.cpp

7 files changed, 248 insertions, 223 deletions

diff --git a/indra/llrender/llgl.cpp b/indra/llrender/llgl.cpp
index 12da961cef..639d1fba32 100644
--- a/indra/llrender/llgl.cpp
+++ b/indra/llrender/llgl.cpp
@@ -757,17 +757,6 @@ bool LLGLManager::initGL()
 
 	stop_glerror();
 
-#if LL_WINDOWS
-	if (mHasDebugOutput && gDebugGL)
-	{ //setup debug output callback
-		//glDebugMessageControlARB(GL_DONT_CARE, GL_DONT_CARE, GL_DEBUG_SEVERITY_LOW_ARB, 0, NULL, GL_TRUE);
-		glDebugMessageCallbackARB((GLDEBUGPROCARB) gl_debug_callback, NULL);
-		glEnable(GL_DEBUG_OUTPUT_SYNCHRONOUS_ARB);
-	}
-#endif
-
-	stop_glerror();
-
 	//HACK always disable texture multisample, use FXAA instead
 	mHasTextureMultisample = FALSE;
 #if LL_WINDOWS
@@ -1029,7 +1018,9 @@ void LLGLManager::initExtensions()
 	mHasSync = ExtensionExists("GL_ARB_sync", gGLHExts.mSysExts);
 	mHasMapBufferRange = ExtensionExists("GL_ARB_map_buffer_range", gGLHExts.mSysExts);
 	mHasFlushBufferRange = ExtensionExists("GL_APPLE_flush_buffer_range", gGLHExts.mSysExts);
-	mHasDepthClamp = ExtensionExists("GL_ARB_depth_clamp", gGLHExts.mSysExts) || ExtensionExists("GL_NV_depth_clamp", gGLHExts.mSysExts);
+    // NOTE: Using extensions breaks reflections when Shadows are set to projector.  See: SL-16727
+    //mHasDepthClamp = ExtensionExists("GL_ARB_depth_clamp", gGLHExts.mSysExts) || ExtensionExists("GL_NV_depth_clamp", gGLHExts.mSysExts);
+    mHasDepthClamp = FALSE;
 	// mask out FBO support when packed_depth_stencil isn't there 'cause we need it for LLRenderTarget -Brad
 #ifdef GL_ARB_framebuffer_object
 	mHasFramebufferObject = ExtensionExists("GL_ARB_framebuffer_object", gGLHExts.mSysExts);
@@ -2159,95 +2150,6 @@ LLGLUserClipPlane::~LLGLUserClipPlane()
 	disable();
 }
 
-LLGLNamePool::LLGLNamePool()
-{
-}
-
-LLGLNamePool::~LLGLNamePool()
-{
-}
-
-void LLGLNamePool::upkeep()
-{
-	std::sort(mNameList.begin(), mNameList.end(), CompareUsed());
-}
-
-void LLGLNamePool::cleanup()
-{
-	for (name_list_t::iterator iter = mNameList.begin(); iter != mNameList.end(); ++iter)
-	{
-		releaseName(iter->name);
-	}
-
-	mNameList.clear();
-}
-
-GLuint LLGLNamePool::allocate()
-{
-    LL_PROFILE_ZONE_SCOPED_CATEGORY_PIPELINE;
-#if LL_GL_NAME_POOLING
-	for (name_list_t::iterator iter = mNameList.begin(); iter != mNameList.end(); ++iter)
-	{
-		if (!iter->used)
-		{
-			iter->used = TRUE;
-			return iter->name;
-		}
-	}
-
-	NameEntry entry;
-	entry.name = allocateName();
-	entry.used = TRUE;
-	mNameList.push_back(entry);
-
-	return entry.name;
-#else
-	return allocateName();
-#endif
-}
-
-void LLGLNamePool::release(GLuint name)
-{
-#if LL_GL_NAME_POOLING
-	for (name_list_t::iterator iter = mNameList.begin(); iter != mNameList.end(); ++iter)
-	{
-		if (iter->name == name)
-		{
-			if (iter->used)
-			{
-				iter->used = FALSE;
-				return;
-			}
-			else
-			{
-				LL_ERRS() << "Attempted to release a pooled name that is not in use!" << LL_ENDL;
-			}
-		}
-	}
-	LL_ERRS() << "Attempted to release a non pooled name!" << LL_ENDL;
-#else
-	releaseName(name);
-#endif
-}
-
-//static
-void LLGLNamePool::upkeepPools()
-{
-	for (auto& pool : instance_snapshot())
-	{
-		pool.upkeep();
-	}
-}
-
-//static
-void LLGLNamePool::cleanupPools()
-{
-	for (auto& pool : instance_snapshot())
-	{
-		pool.cleanup();
-	}
-}
-
 LLGLDepthTest::LLGLDepthTest(GLboolean depth_enabled, GLboolean write_enabled, GLenum depth_func)
 : mPrevDepthEnabled(sDepthEnabled), mPrevDepthFunc(sDepthFunc), mPrevWriteEnabled(sWriteEnabled)
 {
@@ -2469,3 +2371,4 @@ extern "C"
 }
 #endif
 
+
diff --git a/indra/llrender/llgl.h b/indra/llrender/llgl.h
index ec97eb0faa..52338364e6 100644
--- a/indra/llrender/llgl.h
+++ b/indra/llrender/llgl.h
@@ -367,51 +367,6 @@ public:
 };
 
 /*
-	Generic pooling scheme for things which use GL names (used for occlusion queries and vertex buffer objects).
-	Prevents thrashing of GL name caches by avoiding calls to glGenFoo and glDeleteFoo.
-*/
-class LLGLNamePool : public LLInstanceTracker<LLGLNamePool>
-{
-public:
-	typedef LLInstanceTracker<LLGLNamePool> tracker_t;
-
-	struct NameEntry
-	{
-		GLuint name;
-		BOOL used;
-	};
-
-	struct CompareUsed
-	{
-		bool operator()(const NameEntry& lhs, const NameEntry& rhs)
-		{
-			return lhs.used < rhs.used;  //FALSE entries first
-		}
-	};
-
-	typedef std::vector<NameEntry> name_list_t;
-	name_list_t mNameList;
-
-	LLGLNamePool();
-	virtual ~LLGLNamePool();
-	
-	void upkeep();
-	void cleanup();
-	
-	GLuint allocate();
-	void release(GLuint name);
-	
-	static void upkeepPools();
-	static void cleanupPools();
-
-protected:
-	typedef std::vector<LLGLNamePool*> pool_list_t;
-	
-	virtual GLuint allocateName() = 0;
-	virtual void releaseName(GLuint name) = 0;
-};
-
-/*
 	Interface for objects that need periodic GL updates applied to them.
 	Used to synchronize GL updates with GL thread.
 */
diff --git a/indra/llrender/llgltexture.cpp b/indra/llrender/llgltexture.cpp
index b6a02f1c0a..e012eb9a62 100644
--- a/indra/llrender/llgltexture.cpp
+++ b/indra/llrender/llgltexture.cpp
@@ -164,11 +164,11 @@ BOOL LLGLTexture::createGLTexture()
 	return mGLTexturep->createGLTexture() ;
 }
 
-BOOL LLGLTexture::createGLTexture(S32 discard_level, const LLImageRaw* imageraw, S32 usename, BOOL to_create, S32 category)
+BOOL LLGLTexture::createGLTexture(S32 discard_level, const LLImageRaw* imageraw, S32 usename, BOOL to_create, S32 category, bool defer_copy, LLGLuint* tex_name)
 {
-	llassert(mGLTexturep.notNull()) ;	
+	llassert(mGLTexturep.notNull());
 
-	BOOL ret = mGLTexturep->createGLTexture(discard_level, imageraw, usename, to_create, category) ;
+	BOOL ret = mGLTexturep->createGLTexture(discard_level, imageraw, usename, to_create, category, defer_copy, tex_name) ;
 
 	if(ret)
 	{
@@ -260,20 +260,20 @@ LLTexUnit::eTextureType LLGLTexture::getTarget(void) const
 	return mGLTexturep->getTarget() ;
 }
 
-BOOL LLGLTexture::setSubImage(const LLImageRaw* imageraw, S32 x_pos, S32 y_pos, S32 width, S32 height)
+BOOL LLGLTexture::setSubImage(const LLImageRaw* imageraw, S32 x_pos, S32 y_pos, S32 width, S32 height, LLGLuint use_name)
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_TEXTURE;
 	llassert(mGLTexturep.notNull()) ;
 
-	return mGLTexturep->setSubImage(imageraw, x_pos, y_pos, width, height) ;
+	return mGLTexturep->setSubImage(imageraw, x_pos, y_pos, width, height, 0, use_name) ;
 }
 
-BOOL LLGLTexture::setSubImage(const U8* datap, S32 data_width, S32 data_height, S32 x_pos, S32 y_pos, S32 width, S32 height)
+BOOL LLGLTexture::setSubImage(const U8* datap, S32 data_width, S32 data_height, S32 x_pos, S32 y_pos, S32 width, S32 height, LLGLuint use_name)
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_TEXTURE;
 	llassert(mGLTexturep.notNull()) ;
 
-	return mGLTexturep->setSubImage(datap, data_width, data_height, x_pos, y_pos, width, height) ;
+	return mGLTexturep->setSubImage(datap, data_width, data_height, x_pos, y_pos, width, height, 0, use_name) ;
 }
 
 void LLGLTexture::setGLTextureCreated (bool initialized)
diff --git a/indra/llrender/llgltexture.h b/indra/llrender/llgltexture.h
index 028457c510..8cfe7b62de 100644
--- a/indra/llrender/llgltexture.h
+++ b/indra/llrender/llgltexture.h
@@ -124,13 +124,22 @@ public:
 	BOOL       hasGLTexture() const ;
 	LLGLuint   getTexName() const ;		
 	BOOL       createGLTexture() ;
-	BOOL       createGLTexture(S32 discard_level, const LLImageRaw* imageraw, S32 usename = 0, BOOL to_create = TRUE, S32 category = LLGLTexture::OTHER);
+	
+    // Create a GL Texture from an image raw
+    // discard_level - mip level, 0 for highest resultion mip
+    // imageraw - the image to copy from
+    // usename - explicit GL name override
+    // to_create - set to FALSE to force gl texture to not be created
+    // category - LLGLTexture category for this LLGLTexture
+    // defer_copy - set to true to allocate GL texture but NOT initialize with imageraw data
+    // tex_name - if not null, will be set to the GL name of the texture created
+    BOOL       createGLTexture(S32 discard_level, const LLImageRaw* imageraw, S32 usename = 0, BOOL to_create = TRUE, S32 category = LLGLTexture::OTHER, bool defer_copy = false, LLGLuint* tex_name = nullptr);
 
 	void       setFilteringOption(LLTexUnit::eTextureFilterOptions option);
 	void       setExplicitFormat(LLGLint internal_format, LLGLenum primary_format, LLGLenum type_format = 0, BOOL swap_bytes = FALSE);
 	void       setAddressMode(LLTexUnit::eTextureAddressMode mode);
-	BOOL       setSubImage(const LLImageRaw* imageraw, S32 x_pos, S32 y_pos, S32 width, S32 height);
-	BOOL       setSubImage(const U8* datap, S32 data_width, S32 data_height, S32 x_pos, S32 y_pos, S32 width, S32 height);
+	BOOL       setSubImage(const LLImageRaw* imageraw, S32 x_pos, S32 y_pos, S32 width, S32 height, LLGLuint use_name = 0);
+	BOOL       setSubImage(const U8* datap, S32 data_width, S32 data_height, S32 x_pos, S32 y_pos, S32 width, S32 height, LLGLuint use_name = 0);
 	void       setGLTextureCreated (bool initialized);
 	void       setCategory(S32 category) ;
     void       setTexName(LLGLuint); // for forcing w/ externally created textures only
diff --git a/indra/llrender/llimagegl.cpp b/indra/llrender/llimagegl.cpp
index 1e9b9f642e..f43671dee5 100644
--- a/indra/llrender/llimagegl.cpp
+++ b/indra/llrender/llimagegl.cpp
@@ -40,6 +40,7 @@
 #include "llglslshader.h"
 #include "llrender.h"
 #include "llwindow.h"
+#include "llframetimer.h"
 
 #if !LL_IMAGEGL_THREAD_CHECK
 #define checkActiveThread()
@@ -436,7 +437,7 @@ LLImageGL::LLImageGL(
 
 LLImageGL::~LLImageGL()
 {
-    if (!mExternalTexture)
+    if (!mExternalTexture && gGLManager.mInited)
     {
 	    LLImageGL::cleanup();
 	    sImageList.erase(this);
@@ -550,7 +551,7 @@ bool LLImageGL::setSize(S32 width, S32 height, S32 ncomponents, S32 discard_leve
 	if (width != mWidth || height != mHeight || ncomponents != mComponents)
 	{
 		// Check if dimensions are a power of two!
-		if (!checkSize(width,height))
+		if (!checkSize(width, height))
 		{
 			LL_WARNS() << llformat("Texture has non power of two dimension: %dx%d",width,height) << LL_ENDL;
 			return false;
@@ -674,7 +675,7 @@ void LLImageGL::setImage(const LLImageRaw* imageraw)
 	setImage(rawdata, FALSE);
 }
 
-BOOL LLImageGL::setImage(const U8* data_in, BOOL data_hasmips, S32 usename)
+BOOL LLImageGL::setImage(const U8* data_in, BOOL data_hasmips /* = FALSE */, S32 usename /* = 0 */)
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_TEXTURE;
 	bool is_compressed = false;
@@ -709,8 +710,14 @@ BOOL LLImageGL::setImage(const U8* data_in, BOOL data_hasmips, S32 usename)
 	
     gGL.getTexUnit(0)->bind(this, false, false, usename);
 
-
-    if (mUseMipMaps)
+    if (data_in == nullptr)
+    {
+        S32 w = getWidth();
+        S32 h = getHeight();
+        LLImageGL::setManualImage(mTarget, 0, mFormatInternal, w, h,
+            mFormatPrimary, mFormatType, (GLvoid*)data_in, mAllowCompression);
+    }
+    else if (mUseMipMaps)
 	{
 		if (data_hasmips)
 		{
@@ -1069,14 +1076,15 @@ void LLImageGL::postAddToAtlas()
 	stop_glerror();	
 }
 
-BOOL LLImageGL::setSubImage(const U8* datap, S32 data_width, S32 data_height, S32 x_pos, S32 y_pos, S32 width, S32 height, BOOL force_fast_update)
+BOOL LLImageGL::setSubImage(const U8* datap, S32 data_width, S32 data_height, S32 x_pos, S32 y_pos, S32 width, S32 height, BOOL force_fast_update /* = FALSE */, LLGLuint use_name)
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_TEXTURE;
 	if (!width || !height)
 	{
 		return TRUE;
 	}
-	if (mTexName == 0)
+    LLGLuint tex_name = use_name != 0 ? use_name : mTexName;
+	if (0 == tex_name)
 	{
 		// *TODO: Re-enable warning?  Ran into thread locking issues? DK 2011-02-18
 		//LL_WARNS() << "Setting subimage on image without GL texture" << LL_ENDL;
@@ -1092,7 +1100,7 @@ BOOL LLImageGL::setSubImage(const U8* datap, S32 data_width, S32 data_height, S3
 	// HACK: allow the caller to explicitly force the fast path (i.e. using glTexSubImage2D here instead of calling setImage) even when updating the full texture.
 	if (!force_fast_update && x_pos == 0 && y_pos == 0 && width == getWidth() && height == getHeight() && data_width == width && data_height == height)
 	{
-		setImage(datap, FALSE);
+		setImage(datap, FALSE, tex_name);
 	}
 	else
 	{
@@ -1144,12 +1152,11 @@ BOOL LLImageGL::setSubImage(const U8* datap, S32 data_width, S32 data_height, S3
 
 		datap += (y_pos * data_width + x_pos) * getComponents();
 		// Update the GL texture
-		BOOL res = gGL.getTexUnit(0)->bindManual(mBindTarget, mTexName);
+		BOOL res = gGL.getTexUnit(0)->bindManual(mBindTarget, tex_name);
 		if (!res) LL_ERRS() << "LLImageGL::setSubImage(): bindTexture failed" << LL_ENDL;
 		stop_glerror();
 
-		glTexSubImage2D(mTarget, 0, x_pos, y_pos, 
-						width, height, mFormatPrimary, mFormatType, datap);
+		glTexSubImage2D(mTarget, 0, x_pos, y_pos, width, height, mFormatPrimary, mFormatType, datap);
 		gGL.getTexUnit(0)->disable();
 		stop_glerror();
 
@@ -1166,10 +1173,10 @@ BOOL LLImageGL::setSubImage(const U8* datap, S32 data_width, S32 data_height, S3
 	return TRUE;
 }
 
-BOOL LLImageGL::setSubImage(const LLImageRaw* imageraw, S32 x_pos, S32 y_pos, S32 width, S32 height, BOOL force_fast_update)
+BOOL LLImageGL::setSubImage(const LLImageRaw* imageraw, S32 x_pos, S32 y_pos, S32 width, S32 height, BOOL force_fast_update /* = FALSE */, LLGLuint use_name)
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_TEXTURE;
-	return setSubImage(imageraw->getData(), imageraw->getWidth(), imageraw->getHeight(), x_pos, y_pos, width, height, force_fast_update);
+	return setSubImage(imageraw->getData(), imageraw->getWidth(), imageraw->getHeight(), x_pos, y_pos, width, height, force_fast_update, use_name);
 }
 
 // Copy sub image from frame buffer
@@ -1356,7 +1363,7 @@ BOOL LLImageGL::createGLTexture()
 	return TRUE ;
 }
 
-BOOL LLImageGL::createGLTexture(S32 discard_level, const LLImageRaw* imageraw, S32 usename/*=0*/, BOOL to_create, S32 category)
+BOOL LLImageGL::createGLTexture(S32 discard_level, const LLImageRaw* imageraw, S32 usename/*=0*/, BOOL to_create, S32 category, bool defer_copy, LLGLuint* tex_name)
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_TEXTURE;
     checkActiveThread();
@@ -1386,6 +1393,7 @@ BOOL LLImageGL::createGLTexture(S32 discard_level, const LLImageRaw* imageraw, S
 	// Actual image width/height = raw image width/height * 2^discard_level
 	S32 raw_w = imageraw->getWidth() ;
 	S32 raw_h = imageraw->getHeight() ;
+
 	S32 w = raw_w << discard_level;
 	S32 h = raw_h << discard_level;
 
@@ -1468,15 +1476,26 @@ BOOL LLImageGL::createGLTexture(S32 discard_level, const LLImageRaw* imageraw, S
 
 	setCategory(category);
  	const U8* rawdata = imageraw->getData();
-	return createGLTexture(discard_level, rawdata, FALSE, usename);
+	return createGLTexture(discard_level, rawdata, FALSE, usename, defer_copy, tex_name);
 }
 
-BOOL LLImageGL::createGLTexture(S32 discard_level, const U8* data_in, BOOL data_hasmips, S32 usename)
+BOOL LLImageGL::createGLTexture(S32 discard_level, const U8* data_in, BOOL data_hasmips, S32 usename, bool defer_copy, LLGLuint* tex_name)
+// Call with void data, vmem is allocated but unitialized
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_TEXTURE;
     checkActiveThread();
 
-    llassert(data_in);
+    bool main_thread = on_main_thread();
+
+    if (defer_copy)
+    {
+        data_in = nullptr;
+    }
+    else
+    {
+        llassert(data_in);
+    }
+
     stop_glerror();
 
     if (discard_level < 0)
@@ -1486,28 +1505,41 @@ BOOL LLImageGL::createGLTexture(S32 discard_level, const U8* data_in, BOOL data_
     }
     discard_level = llclamp(discard_level, 0, (S32)mMaxDiscardLevel);
 
-    if (mTexName != 0 && discard_level == mCurrentDiscardLevel)
+    if (main_thread // <--- always force creation of new_texname when not on main thread ...
+        && !defer_copy // <--- ... or defer copy is set
+        && mTexName != 0 && discard_level == mCurrentDiscardLevel)
     {
+        LL_PROFILE_ZONE_NAMED("cglt - early setImage");
         // This will only be true if the size has not changed
+        if (tex_name != nullptr)
+        {
+            *tex_name = mTexName;
+        }
         return setImage(data_in, data_hasmips);
     }
 
     GLuint old_texname = mTexName;
-    
+    GLuint new_texname = 0;
     if (usename != 0)
     {
-        mNewTexName = usename;
+        llassert(main_thread);
+        new_texname = usename;
     }
     else
     {
-        LLImageGL::generateTextures(1, &mNewTexName);
+        LLImageGL::generateTextures(1, &new_texname);
         {
-            gGL.getTexUnit(0)->bind(this, false, false, mNewTexName);
+            gGL.getTexUnit(0)->bind(this, false, false, new_texname);
             glTexParameteri(LLTexUnit::getInternalType(mBindTarget), GL_TEXTURE_BASE_LEVEL, 0);
             glTexParameteri(LLTexUnit::getInternalType(mBindTarget), GL_TEXTURE_MAX_LEVEL, mMaxDiscardLevel - discard_level);
         }
     }
-    
+
+    if (tex_name != nullptr)
+    {
+        *tex_name = new_texname;
+    }
+
     if (mUseMipMaps)
     {
         mAutoGenMips = gGLManager.mHasMipMapGeneration;
@@ -1515,9 +1547,12 @@ BOOL LLImageGL::createGLTexture(S32 discard_level, const U8* data_in, BOOL data_
 
     mCurrentDiscardLevel = discard_level;
 
-    if (!setImage(data_in, data_hasmips, mNewTexName))
     {
-        return FALSE;
+        LL_PROFILE_ZONE_NAMED("cglt - late setImage");
+        if (!setImage(data_in, data_hasmips, new_texname))
+        {
+            return FALSE;
+        }
     }
 
     // Set texture options to our defaults.
@@ -1534,47 +1569,23 @@ BOOL LLImageGL::createGLTexture(S32 discard_level, const U8* data_in, BOOL data_
     }
 
     //if we're on the image loading thread, be sure to delete old_texname and update mTexName on the main thread
-    if (! on_main_thread())
+    if (!defer_copy)
     {
+        if (!main_thread)
         {
-            LL_PROFILE_ZONE_NAMED("cglt - sync");
-            if (gGLManager.mHasSync)
-            {
-                auto sync = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
-                glClientWaitSync(sync, 0, 0);
-                glDeleteSync(sync);
-            }
-            else
-            {
-                glFinish();
-            }
+            syncToMainThread(new_texname);
         }
-
-        ref();
-        LL::WorkQueue::postMaybe(
-            mMainQueue,
-            [=]()
-            {
-                LL_PROFILE_ZONE_NAMED("cglt - delete callback");
-                if (old_texname != 0)
-                {
-                    LLImageGL::deleteTextures(1, &old_texname);
-                }
-                mTexName = mNewTexName;
-                mNewTexName = 0;
-                unref();
-            });
-    }
-    else 
-    {
-        //not on background thread, immediately set mTexName
-        if (old_texname != 0)
+        else
         {
-            LLImageGL::deleteTextures(1, &old_texname);
+            //not on background thread, immediately set mTexName
+            if (old_texname != 0 && old_texname != new_texname)
+            {
+                LLImageGL::deleteTextures(1, &old_texname);
+            }
+            mTexName = new_texname;
         }
-        mTexName = mNewTexName;
-        mNewTexName = 0;
     }
+
     
     mTextureMemory = (S32Bytes)getMipBytes(mCurrentDiscardLevel);
     sGlobalTextureMemory += mTextureMemory;
@@ -1587,6 +1598,110 @@ BOOL LLImageGL::createGLTexture(S32 discard_level, const U8* data_in, BOOL data_
     return TRUE;
 }
 
+void LLImageGLThread::updateClass()
+{
+    LL_PROFILE_ZONE_SCOPED;
+
+    // update available vram one per second
+    static LLFrameTimer sTimer;
+
+    if (sTimer.getElapsedSeconds() < 1.f)
+    {
+        return;
+    }
+    
+    sTimer.reset();
+
+    auto func = []()
+    {
+        if (gGLManager.mHasATIMemInfo)
+        {
+            S32 meminfo[4];
+            glGetIntegerv(GL_TEXTURE_FREE_MEMORY_ATI, meminfo);
+            LLImageGLThread::sFreeVRAMMegabytes = meminfo[0];
+
+        }
+        else if (gGLManager.mHasNVXMemInfo)
+        {
+            S32 free_memory;
+            glGetIntegerv(GL_GPU_MEMORY_INFO_CURRENT_AVAILABLE_VIDMEM_NVX, &free_memory);
+            LLImageGLThread::sFreeVRAMMegabytes = free_memory / 1024;
+        }
+    };
+
+    
+    // post update to background thread if available, otherwise execute immediately
+    auto queue = LL::WorkQueue::getInstance("LLImageGL");
+    if (sEnabled)
+    {
+        queue->post(func);
+    }
+    else
+    {
+        llassert(queue == nullptr);
+        func();
+    }
+}
+
+void LLImageGL::syncToMainThread(LLGLuint new_tex_name)
+{
+    LL_PROFILE_ZONE_SCOPED;
+    llassert(!on_main_thread());
+
+    {
+        LL_PROFILE_ZONE_NAMED("cglt - sync");
+        if (gGLManager.mHasSync)
+        {
+            // post a sync to the main thread (will execute before tex name swap lambda below)
+            // glFlush calls here are partly superstitious and partly backed by observation
+            // on AMD hardware
+            glFlush();
+            auto sync = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
+            glFlush();
+            LL::WorkQueue::postMaybe(
+                mMainQueue,
+                [=]()
+                {
+                    LL_PROFILE_ZONE_NAMED("cglt - wait sync");
+                    {
+                        LL_PROFILE_ZONE_NAMED("glWaitSync");
+                        glWaitSync(sync, 0, GL_TIMEOUT_IGNORED);
+                    }
+                    {
+                        LL_PROFILE_ZONE_NAMED("glDeleteSync");
+                        glDeleteSync(sync);
+                    }
+                });
+        }
+        else
+        {
+            glFinish();
+        }
+    }
+
+    ref();
+    LL::WorkQueue::postMaybe(
+        mMainQueue,
+        [=]()
+        {
+            LL_PROFILE_ZONE_NAMED("cglt - delete callback");
+            syncTexName(new_tex_name);
+            unref();
+        });
+}
+
+void LLImageGL::syncTexName(LLGLuint texname)
+{
+    if (texname != 0)
+    {
+        if (mTexName != 0 && mTexName != texname)
+        {
+            LLImageGL::deleteTextures(1, &mTexName);
+        }
+        mTexName = texname;
+    }
+}
+
 BOOL LLImageGL::readBackRaw(S32 discard_level, LLImageRaw* imageraw, bool compressed_ok) const
 {
 	llassert_always(sAllowReadBackRaw) ;
@@ -1714,7 +1829,7 @@ void LLImageGL::destroyGLTexture()
 		mCurrentDiscardLevel = -1 ; //invalidate mCurrentDiscardLevel.
 		mTexName = 0;		
 		mGLTextureCreated = FALSE ;
-	}	
+	}
 }
 
 //force to invalidate the gl texture, most likely a sculpty texture
@@ -2257,6 +2372,8 @@ void LLImageGL::checkActiveThread()
 		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL,  nummips);
 */  
 
+std::atomic<S32> LLImageGLThread::sFreeVRAMMegabytes(4096); //if free vram is unknown, default to 4GB
+
 LLImageGLThread::LLImageGLThread(LLWindow* window)
     // We want exactly one thread, but a very large capacity: we never want
     // anyone, especially inner-loop render code, to have to block on post()
@@ -2283,3 +2400,9 @@ void LLImageGLThread::run()
     gGL.shutdown();
     mWindow->destroySharedContext(mContext);
 }
+
+S32 LLImageGLThread::getFreeVRAMMegabytes()
+{
+    return sFreeVRAMMegabytes;
+}
+
diff --git a/indra/llrender/llimagegl.h b/indra/llrender/llimagegl.h
index d6f4b13a51..4d5b60d6bc 100644
--- a/indra/llrender/llimagegl.h
+++ b/indra/llrender/llimagegl.h
@@ -110,14 +110,18 @@ public:
     
 	BOOL createGLTexture() ;
 	BOOL createGLTexture(S32 discard_level, const LLImageRaw* imageraw, S32 usename = 0, BOOL to_create = TRUE,
-		S32 category = sMaxCategories-1);
-	BOOL createGLTexture(S32 discard_level, const U8* data, BOOL data_hasmips = FALSE, S32 usename = 0);
+		S32 category = sMaxCategories-1, bool defer_copy = false, LLGLuint* tex_name = nullptr);
+	BOOL createGLTexture(S32 discard_level, const U8* data, BOOL data_hasmips = FALSE, S32 usename = 0, bool defer_copy = false, LLGLuint* tex_name = nullptr);
 	void setImage(const LLImageRaw* imageraw);
 	BOOL setImage(const U8* data_in, BOOL data_hasmips = FALSE, S32 usename = 0);
-	BOOL setSubImage(const LLImageRaw* imageraw, S32 x_pos, S32 y_pos, S32 width, S32 height, BOOL force_fast_update = FALSE);
-	BOOL setSubImage(const U8* datap, S32 data_width, S32 data_height, S32 x_pos, S32 y_pos, S32 width, S32 height, BOOL force_fast_update = FALSE);
+	BOOL setSubImage(const LLImageRaw* imageraw, S32 x_pos, S32 y_pos, S32 width, S32 height, BOOL force_fast_update = FALSE, LLGLuint use_name = 0);
+	BOOL setSubImage(const U8* datap, S32 data_width, S32 data_height, S32 x_pos, S32 y_pos, S32 width, S32 height, BOOL force_fast_update = FALSE, LLGLuint use_name = 0);
 	BOOL setSubImageFromFrameBuffer(S32 fb_x, S32 fb_y, S32 x_pos, S32 y_pos, S32 width, S32 height);
-	
+
+    // wait for gl commands to finish on current thread and push
+    // a lambda to main thread to swap mNewTexName and mTexName
+    void syncToMainThread(LLGLuint new_tex_name);
+
 	// Read back a raw image for this discard level, if it exists
 	BOOL readBackRaw(S32 discard_level, LLImageRaw* imageraw, bool compressed_ok) const;
 	void destroyGLTexture();
@@ -220,7 +224,7 @@ private:
 
 	bool     mGLTextureCreated ;
 	LLGLuint mTexName;
-    LLGLuint mNewTexName = 0; // tex name set by background thread to be applied in main thread
+    //LLGLuint mNewTexName = 0; // tex name set by background thread to be applied in main thread
 	U16      mWidth;
 	U16      mHeight;
 	S8       mCurrentDiscardLevel;
@@ -300,6 +304,9 @@ public:
 	
     void setTexName(GLuint texName) { mTexName = texName; }
 
+    //similar to setTexName, but will call deleteTextures on mTexName if mTexName is not 0 or texname
+    void syncTexName(LLGLuint texname);
+
 	//for debug use: show texture size distribution 
 	//----------------------------------------
 	static S32 sCurTexSizeBar ;
@@ -319,6 +326,12 @@ class LLImageGLThread : public LLSimpleton<LLImageGLThread>, LL::ThreadPool
 public:
     // follows gSavedSettings "RenderGLMultiThreaded"
     static bool sEnabled;
+    
+    // app should call this function periodically
+    static void updateClass();
+
+    // free video memory in megabytes
+    static std::atomic<S32> sFreeVRAMMegabytes;
 
     LLImageGLThread(LLWindow* window);
 
@@ -331,6 +344,8 @@ public:
 
     void run() override;
 
+    static S32 getFreeVRAMMegabytes();
+
 private:
     LLWindow* mWindow;
     void* mContext = nullptr;
diff --git a/indra/llrender/llrender.cpp b/indra/llrender/llrender.cpp
index 92d8e6193f..a03a27cf94 100644
--- a/indra/llrender/llrender.cpp
+++ b/indra/llrender/llrender.cpp
@@ -36,6 +36,17 @@
 #include "lltexture.h"
 #include "llshadermgr.h"
 
+#if LL_WINDOWS
+extern void APIENTRY gl_debug_callback(GLenum source,
+                                GLenum type,
+                                GLuint id,
+                                GLenum severity,
+                                GLsizei length,
+                                const GLchar* message,
+                                GLvoid* userParam)
+;
+#endif
+
 thread_local LLRender gGL;
 
 // Handy copies of last good GL matrices
@@ -860,6 +871,15 @@ LLRender::~LLRender()
 
 void LLRender::init()
 {
+#if LL_WINDOWS
+    if (gGLManager.mHasDebugOutput && gDebugGL)
+    { //setup debug output callback
+        //glDebugMessageControlARB(GL_DONT_CARE, GL_DONT_CARE, GL_DEBUG_SEVERITY_LOW_ARB, 0, NULL, GL_TRUE);
+        glDebugMessageCallbackARB((GLDEBUGPROCARB) gl_debug_callback, NULL);
+        glEnable(GL_DEBUG_OUTPUT_SYNCHRONOUS_ARB);
+    }
+#endif
+
     glPixelStorei(GL_PACK_ALIGNMENT, 1);
     glPixelStorei(GL_UNPACK_ALIGNMENT, 1);