12 files changed, 166 insertions, 280 deletions

diff --git a/indra/llrender/llgl.cpp b/indra/llrender/llgl.cpp
index e15157af05..67bd9e277e 100644
--- a/indra/llrender/llgl.cpp
+++ b/indra/llrender/llgl.cpp
@@ -2413,7 +2413,7 @@ void LLGLState::checkStates(const std::string& msg)
 
 	BOOL error = FALSE;
 
-	if (src != GL_SRC_ALPHA || dst != GL_ONE_MINUS_SRC_ALPHA)
+	/*if (src != GL_SRC_ALPHA || dst != GL_ONE_MINUS_SRC_ALPHA)
 	{
 		if (gDebugSession)
 		{
@@ -2424,7 +2424,7 @@ void LLGLState::checkStates(const std::string& msg)
 		{
 			LL_GL_ERRS << "Blend function corrupted: " << std::hex << src << " " << std::hex << dst << "  " << msg << std::dec << LL_ENDL;
 		}
-	}
+	}*/
 	
 	for (boost::unordered_map<LLGLenum, LLGLboolean>::iterator iter = sStateMap.begin();
 		 iter != sStateMap.end(); ++iter)
diff --git a/indra/llrender/llrender.cpp b/indra/llrender/llrender.cpp
index c58fbe6c8e..8ab8d3151b 100644
--- a/indra/llrender/llrender.cpp
+++ b/indra/llrender/llrender.cpp
@@ -370,9 +370,10 @@ bool LLTexUnit::bind(LLRenderTarget* renderTarget, bool bindDepth)
 
 	if (bindDepth)
 	{
-		if (renderTarget->hasStencil())
+
+		if (renderTarget->getDepth() && !renderTarget->canSampleDepth())
 		{
-			LL_ERRS() << "Cannot bind a render buffer for sampling.  Allocate render target without a stencil buffer if sampling of depth buffer is required." << LL_ENDL;
+			LL_ERRS() << "Cannot bind a render buffer for sampling.  Allocate render target with depth buffer sampling enabled." << LL_ENDL;
 		}
 
 		bindManual(renderTarget->getUsage(), renderTarget->getDepth());
diff --git a/indra/llrender/llrendertarget.cpp b/indra/llrender/llrendertarget.cpp
index 01ccf3d314..9827db8084 100644
--- a/indra/llrender/llrendertarget.cpp
+++ b/indra/llrender/llrendertarget.cpp
@@ -67,9 +67,8 @@ LLRenderTarget::LLRenderTarget() :
 	mPreviousResX(0),
 	mPreviousResY(0),
 	mDepth(0),
-	mStencil(0),
 	mUseDepth(false),
-	mRenderDepth(false),
+    mSampleDepth(false),
 	mUsage(LLTexUnit::TT_TEXTURE)
 {
 }
@@ -98,11 +97,11 @@ void LLRenderTarget::resize(U32 resx, U32 resy)
 
 	if (mDepth)
 	{ //resize depth attachment
-		if (mStencil)
+		if (!mSampleDepth)
 		{
 			//use render buffers where stencil buffers are in play
 			glBindRenderbuffer(GL_RENDERBUFFER, mDepth);
-			glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, mResX, mResY);
+			glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, mResX, mResY);
 			glBindRenderbuffer(GL_RENDERBUFFER, 0);
 		}
 		else
@@ -117,7 +116,7 @@ void LLRenderTarget::resize(U32 resx, U32 resy)
 }
 	
 
-bool LLRenderTarget::allocate(U32 resx, U32 resy, U32 color_fmt, bool depth, bool stencil, LLTexUnit::eTextureType usage, bool use_fbo, S32 samples)
+bool LLRenderTarget::allocate(U32 resx, U32 resy, U32 color_fmt, bool depth, bool sample_depth, LLTexUnit::eTextureType usage, bool use_fbo, S32 samples)
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_DISPLAY;
 	resx = llmin(resx, (U32) gGLManager.mGLMaxTextureSize);
@@ -130,9 +129,9 @@ bool LLRenderTarget::allocate(U32 resx, U32 resy, U32 color_fmt, bool depth, boo
 	mResX = resx;
 	mResY = resy;
 
-	mStencil = stencil;
 	mUsage = usage;
-	mUseDepth = depth;
+    mUseDepth = depth;
+    mSampleDepth = sample_depth;
 
 	if ((sUseFBO || use_fbo))
 	{
@@ -150,13 +149,10 @@ bool LLRenderTarget::allocate(U32 resx, U32 resy, U32 color_fmt, bool depth, boo
 		if (mDepth)
 		{
 			glBindFramebuffer(GL_FRAMEBUFFER, mFBO);
-            llassert(!mStencil); // use of stencil buffer is deprecated (performance penalty)
-			if (mStencil)
+            
+			if (!canSampleDepth())
 			{
 				glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, mDepth);
-				stop_glerror();
-				glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, mDepth);
-				stop_glerror();
 			}
 			else
 			{
@@ -315,14 +311,12 @@ bool LLRenderTarget::addColorAttachment(U32 color_fmt)
 bool LLRenderTarget::allocateDepth()
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_DISPLAY;
-	if (mStencil)
+	if (!mSampleDepth)
 	{
-		//use render buffers where stencil buffers are in play
+		//use render buffers if depth buffer won't be sampled
 		glGenRenderbuffers(1, (GLuint *) &mDepth);
 		glBindRenderbuffer(GL_RENDERBUFFER, mDepth);
-		stop_glerror();
-		clear_glerror();
-		glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, mResX, mResY);
+		glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, mResX, mResY);
 		glBindRenderbuffer(GL_RENDERBUFFER, 0);
 	}
 	else
@@ -367,23 +361,15 @@ void LLRenderTarget::shareDepthBuffer(LLRenderTarget& target)
 
 	if (mDepth)
 	{
-		stop_glerror();
 		glBindFramebuffer(GL_FRAMEBUFFER, target.mFBO);
-		stop_glerror();
-
-        llassert(!mStencil); // deprecated -- performance penalty
-		if (mStencil)
+		
+		if (!mSampleDepth)
 		{
 			glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, mDepth);
-			stop_glerror();
-			glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, mDepth);			
-			stop_glerror();
-			target.mStencil = true;
 		}
 		else
 		{
 			glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, LLTexUnit::getInternalType(mUsage), mDepth, 0);
-			stop_glerror();
 		}
 
 		check_framebuffer_status();
@@ -399,15 +385,13 @@ void LLRenderTarget::release()
     LL_PROFILE_ZONE_SCOPED_CATEGORY_DISPLAY;
 	if (mDepth)
 	{
-		if (mStencil)
+		if (!mSampleDepth)
 		{
 			glDeleteRenderbuffers(1, (GLuint*) &mDepth);
-			stop_glerror();
 		}
 		else
 		{
 			LLImageGL::deleteTextures(1, &mDepth);
-			stop_glerror();
 		}
 		mDepth = 0;
 
@@ -419,12 +403,10 @@ void LLRenderTarget::release()
 
 		if (mUseDepth)
 		{ //detach shared depth buffer
-            llassert(!mStencil); //deprecated, performance penalty
-			if (mStencil)
+            if (!mSampleDepth)
 			{ //attached as a renderbuffer
-				glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, 0);
 				glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, 0);
-				mStencil = false;
+                mSampleDepth = false;
 			}
 			else
 			{ //attached as a texture
@@ -624,84 +606,6 @@ void LLRenderTarget::flush(bool fetch_depth)
 	}
 }
 
-void LLRenderTarget::copyContents(LLRenderTarget& source, S32 srcX0, S32 srcY0, S32 srcX1, S32 srcY1,
-						S32 dstX0, S32 dstY0, S32 dstX1, S32 dstY1, U32 mask, U32 filter)
-{
-    LL_PROFILE_GPU_ZONE("LLRenderTarget::copyContents");
-
-	GLboolean write_depth = mask & GL_DEPTH_BUFFER_BIT ? TRUE : FALSE;
-
-	LLGLDepthTest depth(write_depth, write_depth);
-
-	gGL.flush();
-	if (!source.mFBO || !mFBO)
-	{
-		LL_WARNS() << "Cannot copy framebuffer contents for non FBO render targets." << LL_ENDL;
-		return;
-	}
-
-	
-	if (mask == GL_DEPTH_BUFFER_BIT && source.mStencil != mStencil)
-	{
-		stop_glerror();
-		
-		glBindFramebuffer(GL_FRAMEBUFFER, source.mFBO);
-		check_framebuffer_status();
-		gGL.getTexUnit(0)->bind(this, true);
-		stop_glerror();
-		glCopyTexSubImage2D(LLTexUnit::getInternalType(mUsage), 0, srcX0, srcY0, dstX0, dstY0, dstX1, dstY1);
-		stop_glerror();
-		glBindFramebuffer(GL_FRAMEBUFFER, sCurFBO);
-		stop_glerror();
-	}
-	else
-	{
-		glBindFramebuffer(GL_READ_FRAMEBUFFER, source.mFBO);
-		stop_glerror();
-		glBindFramebuffer(GL_DRAW_FRAMEBUFFER, mFBO);
-		stop_glerror();
-		check_framebuffer_status();
-		stop_glerror();
-		glBlitFramebuffer(srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1, mask, filter);
-		stop_glerror();
-		glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
-		stop_glerror();
-		glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
-		stop_glerror();
-		glBindFramebuffer(GL_FRAMEBUFFER, sCurFBO);
-		stop_glerror();
-	}
-}
-
-//static
-void LLRenderTarget::copyContentsToFramebuffer(LLRenderTarget& source, S32 srcX0, S32 srcY0, S32 srcX1, S32 srcY1,
-						S32 dstX0, S32 dstY0, S32 dstX1, S32 dstY1, U32 mask, U32 filter)
-{
-	if (!source.mFBO)
-	{
-		LL_WARNS() << "Cannot copy framebuffer contents for non FBO render targets." << LL_ENDL;
-		return;
-	}
-
-	{
-        LL_PROFILE_GPU_ZONE("copyContentsToFramebuffer");
-		GLboolean write_depth = mask & GL_DEPTH_BUFFER_BIT ? TRUE : FALSE;
-
-		LLGLDepthTest depth(write_depth, write_depth);
-		
-		glBindFramebuffer(GL_READ_FRAMEBUFFER, source.mFBO);
-		stop_glerror();
-		glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
-		stop_glerror();
-		check_framebuffer_status();
-		stop_glerror();
-		glBlitFramebuffer(srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1, mask, filter);
-		stop_glerror();
-		glBindFramebuffer(GL_FRAMEBUFFER, sCurFBO);
-		stop_glerror();
-	}
-}
-
 bool LLRenderTarget::isComplete() const
 {
 	return (!mTex.empty() || mDepth) ? true : false;
diff --git a/indra/llrender/llrendertarget.h b/indra/llrender/llrendertarget.h
index 584f224dca..5f3214add3 100644
--- a/indra/llrender/llrendertarget.h
+++ b/indra/llrender/llrendertarget.h
@@ -73,7 +73,7 @@ public:
 	//allocate resources for rendering
 	//must be called before use
 	//multiple calls will release previously allocated resources
-	bool allocate(U32 resx, U32 resy, U32 color_fmt, bool depth, bool stencil, LLTexUnit::eTextureType usage = LLTexUnit::TT_TEXTURE, bool use_fbo = false, S32 samples = 0);
+	bool allocate(U32 resx, U32 resy, U32 color_fmt, bool depth, bool sample_depth, LLTexUnit::eTextureType usage = LLTexUnit::TT_TEXTURE, bool use_fbo = false, S32 samples = 0);
 
 	//resize existing attachments to use new resolution and color format
 	// CAUTION: if the GL runs out of memory attempting to resize, this render target will be undefined
@@ -136,7 +136,7 @@ public:
 	U32 getNumTextures() const;
 
 	U32 getDepth(void) const { return mDepth; }
-	bool hasStencil() const { return mStencil; }
+	bool canSampleDepth() const { return mSampleDepth; }
 
 	void bindTexture(U32 index, S32 channel, LLTexUnit::eTextureFilterOptions filter_options = LLTexUnit::TFO_BILINEAR);
 
@@ -148,12 +148,6 @@ public:
 	// the current depth texture.  A depth texture will be allocated if needed.
 	void flush(bool fetch_depth = FALSE);
 
-	void copyContents(LLRenderTarget& source, S32 srcX0, S32 srcY0, S32 srcX1, S32 srcY1,
-						S32 dstX0, S32 dstY0, S32 dstX1, S32 dstY1, U32 mask, U32 filter);
-
-	static void copyContentsToFramebuffer(LLRenderTarget& source, S32 srcX0, S32 srcY0, S32 srcX1, S32 srcY1,
-						S32 dstX0, S32 dstY0, S32 dstX1, S32 dstY1, U32 mask, U32 filter);
-
 	//Returns TRUE if target is ready to be rendered into.
 	//That is, if the target has been allocated with at least
 	//one renderable attachment (i.e. color buffer, depth buffer).
@@ -172,9 +166,9 @@ protected:
 	U32 mPreviousResY;
 
 	U32 mDepth;
-	bool mStencil;
-	bool mUseDepth;
-	bool mRenderDepth;
+    bool mUseDepth;
+    bool mSampleDepth;
+
 	LLTexUnit::eTextureType mUsage;
 	
 	static LLRenderTarget* sBoundTarget;
diff --git a/indra/newview/app_settings/shaders/class1/interface/copyF.glsl b/indra/newview/app_settings/shaders/class1/interface/copyF.glsl
new file mode 100644
index 0000000000..764bace621
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/interface/copyF.glsl
@@ -0,0 +1,40 @@
+/** 
+ * @file copyF.glsl
+ *
+ * $LicenseInfo:firstyear=2023&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2023, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+in vec2 tc;
+
+uniform sampler2D depthMap;
+uniform sampler2D diffuseMap;
+
+out vec4 frag_color;
+
+void main() 
+{
+    frag_color = texture(diffuseMap, tc);
+#if COPY_DEPTH
+    gl_FragDepth = texture(depthMap, tc).r;
+#endif
+}
+
diff --git a/indra/newview/app_settings/shaders/class1/interface/copyV.glsl b/indra/newview/app_settings/shaders/class1/interface/copyV.glsl
new file mode 100644
index 0000000000..ace5da6578
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/interface/copyV.glsl
@@ -0,0 +1,34 @@
+/** 
+ * @file copyV.glsl
+ *
+ * $LicenseInfo:firstyear=2023&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2023, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+
+in vec3 position;
+out vec2 tc;
+
+void main() 
+{
+    tc = position.xy * 0.5 + 0.5;
+    gl_Position = vec4(position, 1.0);
+}
diff --git a/indra/newview/lldrawpoolwater.cpp b/indra/newview/lldrawpoolwater.cpp
index 77da29061d..c2fe52683b 100644
--- a/indra/newview/lldrawpoolwater.cpp
+++ b/indra/newview/lldrawpoolwater.cpp
@@ -133,11 +133,28 @@ void LLDrawPoolWater::beginPostDeferredPass(S32 pass)
         // reflections and refractions
         LLRenderTarget& src = gPipeline.mRT->screen;
         LLRenderTarget& dst = gPipeline.mWaterDis;
+
+#if 0
         dst.copyContents(src,
             0, 0, src.getWidth(), src.getHeight(),
             0, 0, dst.getWidth(), dst.getHeight(),
             GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT,
             GL_NEAREST);
+#else
+        dst.bindTarget();
+        gCopyDepthProgram.bind();
+
+        S32 diff_map = gCopyDepthProgram.enableTexture(LLShaderMgr::DIFFUSE_MAP);
+        S32 depth_map = gCopyDepthProgram.enableTexture(LLShaderMgr::DEFERRED_DEPTH);
+
+        gGL.getTexUnit(diff_map)->bind(&src);
+        gGL.getTexUnit(depth_map)->bind(&src, true);
+
+        gPipeline.mScreenTriangleVB->setBuffer(LLVertexBuffer::MAP_VERTEX);
+        gPipeline.mScreenTriangleVB->drawArrays(LLRender::TRIANGLES, 0, 3);
+
+        dst.flush();
+#endif
     }
 }
 
diff --git a/indra/newview/llviewerdisplay.cpp b/indra/newview/llviewerdisplay.cpp
index 58b1716caa..01fca47184 100644
--- a/indra/newview/llviewerdisplay.cpp
+++ b/indra/newview/llviewerdisplay.cpp
@@ -967,13 +967,6 @@ void display(BOOL rebuild, F32 zoom_factor, int subfield, BOOL for_snapshot)
         LLRenderTarget &rt = (gPipeline.sRenderDeferred ? gPipeline.mRT->deferredScreen : gPipeline.mRT->screen);
         rt.flush();
 
-        /*if (rt.sUseFBO)
-        {
-            LLRenderTarget::copyContentsToFramebuffer(rt, 0, 0, rt.getWidth(), rt.getHeight(), 0, 0, rt.getWidth(),
-                                                      rt.getHeight(), GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT,
-                                                      GL_NEAREST);
-        }*/
-
         if (LLPipeline::sRenderDeferred)
         {
 			gPipeline.renderDeferredLighting();
@@ -1364,6 +1357,8 @@ void render_ui(F32 zoom_factor, int subfield)
 		render_hud_elements();
 		render_hud_attachments();
 
+        LLGLState::checkStates();
+
 		LLGLSDefault gls_default;
 		LLGLSUIDefault gls_ui;
 		{
@@ -1378,6 +1373,7 @@ void render_ui(F32 zoom_factor, int subfield)
             if (!gDisconnected)
             {
                 LL_PROFILE_ZONE_NAMED_CATEGORY_UI("UI 3D"); //LL_RECORD_BLOCK_TIME(FTM_RENDER_UI_3D);
+                LLGLState::checkStates();
                 render_ui_3d();
                 LLGLState::checkStates();
             }
diff --git a/indra/newview/llviewershadermgr.cpp b/indra/newview/llviewershadermgr.cpp
index 757a946fda..8dd01a3a29 100644
--- a/indra/newview/llviewershadermgr.cpp
+++ b/indra/newview/llviewershadermgr.cpp
@@ -93,6 +93,8 @@ LLGLSLShader	gDownsampleDepthRectProgram;
 LLGLSLShader	gAlphaMaskProgram;
 LLGLSLShader	gBenchmarkProgram;
 LLGLSLShader    gReflectionProbeDisplayProgram;
+LLGLSLShader    gCopyProgram;
+LLGLSLShader    gCopyDepthProgram;
 
 //object shaders
 LLGLSLShader		gObjectSimpleProgram;
@@ -3916,6 +3918,27 @@ BOOL LLViewerShaderMgr::loadShadersInterface()
         success = gReflectionProbeDisplayProgram.createShader(NULL, NULL);
     }
 
+    if (success)
+    {
+        gCopyProgram.mName = "Copy Shader";
+        gCopyProgram.mShaderFiles.clear();
+        gCopyProgram.mShaderFiles.push_back(make_pair("interface/copyV.glsl", GL_VERTEX_SHADER));
+        gCopyProgram.mShaderFiles.push_back(make_pair("interface/copyF.glsl", GL_FRAGMENT_SHADER));
+        gCopyProgram.mShaderLevel = mShaderLevel[SHADER_INTERFACE];
+        success = gCopyProgram.createShader(NULL, NULL);
+    }
+
+    if (success)
+    {
+        gCopyDepthProgram.mName = "Copy Depth Shader";
+        gCopyDepthProgram.mShaderFiles.clear();
+        gCopyDepthProgram.mShaderFiles.push_back(make_pair("interface/copyV.glsl", GL_VERTEX_SHADER));
+        gCopyDepthProgram.mShaderFiles.push_back(make_pair("interface/copyF.glsl", GL_FRAGMENT_SHADER));
+        gCopyDepthProgram.clearPermutations();
+        gCopyDepthProgram.addPermutation("COPY_DEPTH", "1");
+        gCopyDepthProgram.mShaderLevel = mShaderLevel[SHADER_INTERFACE];
+        success = gCopyDepthProgram.createShader(NULL, NULL);
+    }
     
 	if (success)
 	{
diff --git a/indra/newview/llviewershadermgr.h b/indra/newview/llviewershadermgr.h
index 9ded72c6a7..d9c8dc5b07 100644
--- a/indra/newview/llviewershadermgr.h
+++ b/indra/newview/llviewershadermgr.h
@@ -164,6 +164,8 @@ extern LLGLSLShader			gDownsampleDepthProgram;
 extern LLGLSLShader			gDownsampleDepthRectProgram;
 extern LLGLSLShader			gBenchmarkProgram;
 extern LLGLSLShader         gReflectionProbeDisplayProgram;
+extern LLGLSLShader         gCopyProgram;
+extern LLGLSLShader         gCopyDepthProgram;
 
 //output tex0[tc0] + tex1[tc1]
 extern LLGLSLShader			gTwoTextureAddProgram;
diff --git a/indra/newview/pipeline.cpp b/indra/newview/pipeline.cpp
index 9851d4bc6a..b5271a6ca1 100644
--- a/indra/newview/pipeline.cpp
+++ b/indra/newview/pipeline.cpp
@@ -858,14 +858,12 @@ bool LLPipeline::allocateScreenBuffer(U32 resX, U32 resY, U32 samples)
 		const U32 occlusion_divisor = 3;
 
 		//allocate deferred rendering color buffers
-		if (!mRT->deferredScreen.allocate(resX, resY, GL_RGBA, TRUE, FALSE, LLTexUnit::TT_TEXTURE, FALSE, samples)) return false;
-		//if (!mRT->deferredDepth.allocate(resX, resY, 0, TRUE, FALSE, LLTexUnit::TT_TEXTURE, FALSE, samples)) return false;
-		if (!mRT->occlusionDepth.allocate(resX/occlusion_divisor, resY/occlusion_divisor, 0, TRUE, FALSE, LLTexUnit::TT_TEXTURE, FALSE, samples)) return false;
+		if (!mRT->deferredScreen.allocate(resX, resY, GL_RGBA, true, true, LLTexUnit::TT_TEXTURE, false, samples)) return false;
 		if (!addDeferredAttachments(mRT->deferredScreen)) return false;
 	
 		GLuint screenFormat = GL_RGBA16;
         
-		if (!mRT->screen.allocate(resX, resY, screenFormat, FALSE, FALSE, LLTexUnit::TT_TEXTURE, FALSE, samples)) return false;
+		if (!mRT->screen.allocate(resX, resY, screenFormat, FALSE, true, LLTexUnit::TT_TEXTURE, FALSE, samples)) return false;
 
         mRT->deferredScreen.shareDepthBuffer(mRT->screen);
 
@@ -905,9 +903,7 @@ bool LLPipeline::allocateScreenBuffer(U32 resX, U32 resY, U32 samples)
 		mRT->fxaaBuffer.release();
 		mRT->screen.release();
 		mRT->deferredScreen.release(); //make sure to release any render targets that share a depth buffer with mRT->deferredScreen first
-		//mRT->deferredDepth.release();
-		mRT->occlusionDepth.release();
-						
+		
 		if (!mRT->screen.allocate(resX, resY, GL_RGBA, TRUE, TRUE, LLTexUnit::TT_TEXTURE, FALSE)) return false;		
 	}
 	
@@ -926,8 +922,6 @@ bool LLPipeline::allocateShadowBuffer(U32 resX, U32 resY)
     LL_PROFILE_ZONE_SCOPED_CATEGORY_DISPLAY;
     S32 shadow_detail = RenderShadowDetail;
 
-    const U32 occlusion_divisor = 3;
-
     F32 scale = llmax(0.f, RenderShadowResolutionScale);
     U32 sun_shadow_map_width = BlurHappySize(resX, scale);
     U32 sun_shadow_map_height = BlurHappySize(resY, scale);
@@ -936,12 +930,7 @@ bool LLPipeline::allocateShadowBuffer(U32 resX, U32 resY)
     { //allocate 4 sun shadow maps
         for (U32 i = 0; i < 4; i++)
         {
-            if (!mRT->shadow[i].allocate(sun_shadow_map_width, sun_shadow_map_height, 0, TRUE, FALSE, LLTexUnit::TT_TEXTURE))
-            {
-                return false;
-            }
-
-            if (!mRT->shadowOcclusion[i].allocate(sun_shadow_map_width / occlusion_divisor, sun_shadow_map_height / occlusion_divisor, 0, TRUE, FALSE, LLTexUnit::TT_TEXTURE))
+            if (!mRT->shadow[i].allocate(sun_shadow_map_width, sun_shadow_map_height, 0, true, true, LLTexUnit::TT_TEXTURE))
             {
                 return false;
             }
@@ -966,11 +955,7 @@ bool LLPipeline::allocateShadowBuffer(U32 resX, U32 resY)
             U32 spot_shadow_map_height = height;
             for (U32 i = 0; i < 2; i++)
             {
-                if (!mSpotShadow[i].allocate(spot_shadow_map_width, spot_shadow_map_height, 0, TRUE, FALSE))
-                {
-                    return false;
-                }
-                if (!mSpotShadowOcclusion[i].allocate(spot_shadow_map_width / occlusion_divisor, height / occlusion_divisor, 0, TRUE, FALSE))
+                if (!mSpotShadow[i].allocate(spot_shadow_map_width, spot_shadow_map_height, 0, true, true))
                 {
                     return false;
                 }
@@ -1001,7 +986,7 @@ bool LLPipeline::allocateShadowBuffer(U32 resX, U32 resY)
         }
     }
 
-    if (shadow_detail > 1)
+    if (shadow_detail > 1 && !gCubeSnapshot)
     {
         for (U32 i = 0; i < 2; i++)
         {
@@ -1198,7 +1183,6 @@ void LLPipeline::releaseScreenBuffers()
 	mRT->deferredScreen.release();
 	mRT->deferredDepth.release();
 	mRT->deferredLight.release();
-	mRT->occlusionDepth.release();
 }
 		
 		
@@ -1206,7 +1190,6 @@ void LLPipeline::releaseSunShadowTarget(U32 index)
 {
     llassert(index < 4);
     mRT->shadow[index].release();
-    mRT->shadowOcclusion[index].release();
 }
 
 void LLPipeline::releaseSunShadowTargets()
@@ -1224,7 +1207,6 @@ void LLPipeline::releaseSpotShadowTargets()
         for (U32 i = 0; i < 2; i++)
         {
             mSpotShadow[i].release();
-            mSpotShadowOcclusion[i].release();
         }
     }
 }
@@ -1239,7 +1221,7 @@ void LLPipeline::createGLBuffers()
 	if (LLPipeline::sRenderTransparentWater)
 	{ //water reflection texture
 		U32 res = (U32) llmax(gSavedSettings.getS32("RenderWaterRefResolution"), 512);
-        mWaterDis.allocate(res,res,GL_RGBA,TRUE,FALSE,LLTexUnit::TT_TEXTURE);
+        mWaterDis.allocate(res,res,GL_RGBA,true,true,LLTexUnit::TT_TEXTURE);
 	}
 
     // Use FBO for bake tex
@@ -2355,9 +2337,6 @@ static LLTrace::BlockTimerStatHandle FTM_CULL("Object Culling");
 
 void LLPipeline::updateCull(LLCamera& camera, LLCullResult& result, LLPlane* planep)
 {
-	static LLCachedControl<bool> use_occlusion(gSavedSettings,"UseOcclusion");
-    static bool can_use_occlusion = LLFeatureManager::getInstance()->isFeatureAvailable("UseOcclusion");
-
     LL_PROFILE_ZONE_SCOPED_CATEGORY_PIPELINE; //LL_RECORD_BLOCK_TIME(FTM_CULL);
 
     if (planep != nullptr)
@@ -2373,56 +2352,6 @@ void LLPipeline::updateCull(LLCamera& camera, LLCullResult& result, LLPlane* pla
 
 	sCull->clear();
 
-	bool to_texture = LLPipeline::sUseOcclusion > 1 && gPipeline.shadersLoaded();
-
-	if (to_texture)
-	{
-		if (LLPipeline::sRenderDeferred && can_use_occlusion)
-		{
-			mRT->occlusionDepth.bindTarget();
-		}
-		else
-		{
-			mRT->screen.bindTarget();
-		}
-	}
-
-	if (sUseOcclusion > 1)
-	{
-		gGL.setColorMask(false, false);
-	}
-
-	gGL.matrixMode(LLRender::MM_PROJECTION);
-	gGL.pushMatrix();
-	gGL.loadMatrix(gGLLastProjection);
-	gGL.matrixMode(LLRender::MM_MODELVIEW);
-	gGL.pushMatrix();
-	gGLLastMatrix = NULL;
-	gGL.loadMatrix(gGLLastModelView);
-
-	LLGLDisable blend(GL_BLEND);
-	LLGLDisable test(GL_ALPHA_TEST);
-	gGL.getTexUnit(0)->unbind(LLTexUnit::TT_TEXTURE);
-
-	LLGLDepthTest depth(GL_TRUE, GL_FALSE);
-
-	bool bound_shader = false;
-	if (gPipeline.shadersLoaded() && LLGLSLShader::sCurBoundShader == 0)
-	{ //if no shader is currently bound, use the occlusion shader instead of fixed function if we can
-		// (shadow render uses a special shader that clamps to clip planes)
-		bound_shader = true;
-		gOcclusionCubeProgram.bind();
-	}
-	
-	if (sUseOcclusion > 1)
-	{
-		if (mCubeVB.isNull())
-		{ //cube VB will be used for issuing occlusion queries
-			mCubeVB = ll_create_cube_vb(LLVertexBuffer::MAP_VERTEX, GL_STATIC_DRAW);
-		}
-		mCubeVB->setBuffer(LLVertexBuffer::MAP_VERTEX);
-	}
-	
 	for (LLWorld::region_list_t::const_iterator iter = LLWorld::getInstance()->getRegionList().begin(); 
 			iter != LLWorld::getInstance()->getRegionList().end(); ++iter)
 	{
@@ -2444,16 +2373,10 @@ void LLPipeline::updateCull(LLCamera& camera, LLCullResult& result, LLPlane* pla
 		LLVOCachePartition* vo_part = region->getVOCachePartition();
 		if(vo_part)
 		{
-            bool do_occlusion_cull = can_use_occlusion && use_occlusion && !gUseWireframe;
-			vo_part->cull(camera, do_occlusion_cull);
+			vo_part->cull(camera, sUseOcclusion > 0);
 		}
 	}
 
-	if (bound_shader)
-	{
-		gOcclusionCubeProgram.unbind();
-	}
-
 	if (hasRenderType(LLPipeline::RENDER_TYPE_SKY) && 
 		gSky.mVOSkyp.notNull() && 
 		gSky.mVOSkyp->mDrawable.notNull())
@@ -2479,28 +2402,6 @@ void LLPipeline::updateCull(LLCamera& camera, LLCullResult& result, LLPlane* pla
     {
         LLWorld::getInstance()->precullWaterObjects(camera, sCull, render_water);
     }
-	
-	gGL.matrixMode(LLRender::MM_PROJECTION);
-	gGL.popMatrix();
-	gGL.matrixMode(LLRender::MM_MODELVIEW);
-	gGL.popMatrix();
-
-	if (sUseOcclusion > 1)
-	{
-		gGL.setColorMask(true, false);
-	}
-
-	if (to_texture)
-	{
-		if (LLPipeline::sRenderDeferred && can_use_occlusion)
-		{
-			mRT->occlusionDepth.flush();
-		}
-		else
-		{
-			mRT->screen.flush();
-		}
-	}
 }
 
 void LLPipeline::markNotCulled(LLSpatialGroup* group, LLCamera& camera)
@@ -2563,6 +2464,9 @@ void LLPipeline::markOccluder(LLSpatialGroup* group)
 
 void LLPipeline::downsampleDepthBuffer(LLRenderTarget& source, LLRenderTarget& dest, LLRenderTarget* scratch_space)
 {
+    LL_PROFILE_ZONE_SCOPED_CATEGORY_PIPELINE;
+    LL_PROFILE_GPU_ZONE("downsampleDepthBuffer");
+
 	LLGLSLShader* last_shader = LLGLSLShader::sCurBoundShaderPtr;
 
 	LLGLSLShader* shader = NULL;
@@ -2570,12 +2474,12 @@ void LLPipeline::downsampleDepthBuffer(LLRenderTarget& source, LLRenderTarget& d
 	if (scratch_space)
 	{
         GLint bits = 0;
-        llassert(!source.hasStencil()); // stencil buffer usage is deprecated
-        bits |= (source.hasStencil() && dest.hasStencil()) ? GL_STENCIL_BUFFER_BIT : 0;
-        bits |= GL_DEPTH_BUFFER_BIT;
+        bits = GL_DEPTH_BUFFER_BIT;
+#if 0  // TODO -- restore occlusion culling functionality
 		scratch_space->copyContents(source, 
 									0, 0, source.getWidth(), source.getHeight(), 
 									0, 0, scratch_space->getWidth(), scratch_space->getHeight(), bits, GL_NEAREST);
+#endif
 	}
 
 	dest.bindTarget();
@@ -2624,23 +2528,6 @@ void LLPipeline::downsampleDepthBuffer(LLRenderTarget& source, LLRenderTarget& d
 	}
 }
 
-void LLPipeline::doOcclusion(LLCamera& camera, LLRenderTarget& source, LLRenderTarget& dest, LLRenderTarget* scratch_space)
-{
-    LL_PROFILE_ZONE_SCOPED_CATEGORY_DISPLAY;
-    llassert(!gCubeSnapshot);
-#if 0
-	downsampleDepthBuffer(source, dest, scratch_space);
-	dest.bindTarget();
-	doOcclusion(camera);
-	dest.flush();
-#else
-    // none of the above shenanigans should matter (enough) because we've preserved hierarchical Z before issuing occlusion queries
-    //source.bindTarget();
-    doOcclusion(camera);
-    //source.flush();
-#endif
-}
-
 void LLPipeline::doOcclusion(LLCamera& camera)
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_PIPELINE;
@@ -9572,13 +9459,8 @@ void LLPipeline::renderShadow(glh::matrix4f& view, glh::matrix4f& proj, LLCamera
         gDeferredShadowCubeProgram.bind();
     }
 
-    LLRenderTarget& occlusion_target = LLViewerCamera::sCurCameraID >= LLViewerCamera::CAMERA_SPOT_SHADOW0 ?
-        mSpotShadowOcclusion[LLViewerCamera::sCurCameraID - LLViewerCamera::CAMERA_SPOT_SHADOW0] :
-        mRT->shadowOcclusion[LLViewerCamera::sCurCameraID - LLViewerCamera::CAMERA_SUN_SHADOW0];
-
-    occlusion_target.bindTarget();
+    
     updateCull(shadow_cam, result);
-    occlusion_target.flush();
 
     stateSort(shadow_cam, result);
 
@@ -9661,6 +9543,12 @@ void LLPipeline::renderShadow(glh::matrix4f& view, glh::matrix4f& proj, LLCamera
         }
     }
 
+    if (occlude > 1)
+    { // do occlusion culling against non-masked only to take advantage of hierarchical Z
+        doOcclusion(shadow_cam);
+    }
+
+
     if (use_shader)
     {
         LL_PROFILE_ZONE_NAMED_CATEGORY_PIPELINE("shadow geom");
@@ -9760,15 +9648,6 @@ void LLPipeline::renderShadow(glh::matrix4f& view, glh::matrix4f& proj, LLCamera
     gGLLastMatrix = NULL;
     gGL.loadMatrix(gGLModelView);
 
-    LLRenderTarget& occlusion_source = LLViewerCamera::sCurCameraID >= LLViewerCamera::CAMERA_SPOT_SHADOW0 ?
-        mSpotShadow[LLViewerCamera::sCurCameraID - LLViewerCamera::CAMERA_SPOT_SHADOW0] :
-        mRT->shadow[LLViewerCamera::sCurCameraID - LLViewerCamera::CAMERA_SUN_SHADOW0];
-
-    if (occlude > 1)
-    {
-        doOcclusion(shadow_cam, occlusion_source, occlusion_target);
-    }
-
     if (use_shader)
     {
         gDeferredShadowProgram.unbind();
diff --git a/indra/newview/pipeline.h b/indra/newview/pipeline.h
index c698374c8b..ae4ac4c7ff 100644
--- a/indra/newview/pipeline.h
+++ b/indra/newview/pipeline.h
@@ -173,7 +173,6 @@ public:
 	// if source's depth buffer cannot be bound for reading, a scratch space depth buffer must be provided
 	void		downsampleDepthBuffer(LLRenderTarget& source, LLRenderTarget& dest, LLRenderTarget* scratch_space = NULL);
 
-	void		doOcclusion(LLCamera& camera, LLRenderTarget& source, LLRenderTarget& dest, LLRenderTarget* scratch_space = NULL);
 	void		doOcclusion(LLCamera& camera);
 	void		markNotCulled(LLSpatialGroup* group, LLCamera &camera);
 	void        markMoved(LLDrawable *drawablep, bool damped_motion = false);
@@ -673,12 +672,10 @@ public:
         LLRenderTarget			fxaaBuffer;
         LLRenderTarget			edgeMap;
         LLRenderTarget			deferredDepth;
-        LLRenderTarget			occlusionDepth;
         LLRenderTarget			deferredLight;
 
         //sun shadow map
         LLRenderTarget			shadow[4];
-        LLRenderTarget			shadowOcclusion[4];
     };
 
     // main full resoltuion render target
@@ -691,7 +688,6 @@ public:
     RenderTargetPack* mRT;
 
     LLRenderTarget          mSpotShadow[2];
-    LLRenderTarget          mSpotShadowOcclusion[2];
 
     LLRenderTarget          mPbrBrdfLut;