3 files changed, 41 insertions, 0 deletions
diff --git a/indra/llrender/llgl.cpp b/indra/llrender/llgl.cpp
index 3400a72385..187a9a984e 100644
--- a/indra/llrender/llgl.cpp
+++ b/indra/llrender/llgl.cpp
@@ -1919,6 +1919,16 @@ LLGLDepthTest::LLGLDepthTest(GLboolean depth_enabled, GLboolean write_enabled, G
 : mPrevDepthEnabled(sDepthEnabled), mPrevDepthFunc(sDepthFunc), mPrevWriteEnabled(sWriteEnabled)
 {
 	stop_glerror();
+	
+	checkState();
+
+	if (!depth_enabled)
+	{ // always disable depth writes if depth testing is disabled
+	  // GL spec defines this as a requirement, but some implementations allow depth writes with testing disabled
+	  // The proper way to write to depth buffer with testing disabled is to enable testing and use a depth_func of GL_ALWAYS
+		write_enabled = FALSE;
+	}
+
 	if (depth_enabled != sDepthEnabled)
 	{
 		gGL.flush();
@@ -1942,6 +1952,7 @@ LLGLDepthTest::LLGLDepthTest(GLboolean depth_enabled, GLboolean write_enabled, G
 
 LLGLDepthTest::~LLGLDepthTest()
 {
+	checkState();
 	if (sDepthEnabled != mPrevDepthEnabled )
 	{
 		gGL.flush();
@@ -1963,6 +1974,32 @@ LLGLDepthTest::~LLGLDepthTest()
 	}
 }
 
+void LLGLDepthTest::checkState()
+{
+	if (gDebugGL)
+	{
+		GLint func = 0;
+		GLboolean mask = FALSE;
+
+		glGetIntegerv(GL_DEPTH_FUNC, &func);
+		glGetBooleanv(GL_DEPTH_WRITEMASK, &mask);
+
+		if (glIsEnabled(GL_DEPTH_TEST) != sDepthEnabled ||
+			sWriteEnabled != mask ||
+			sDepthFunc != func)
+		{
+			if (gDebugSession)
+			{
+				gFailLog << "Unexpected depth testing state." << std::endl;
+			}
+			else
+			{
+				LL_GL_ERRS << "Unexpected depth testing state." << LL_ENDL;
+			}
+		}
+	}
+}
+
 LLGLClampToFarClip::LLGLClampToFarClip(glh::matrix4f P)
 {
 	for (U32 i = 0; i < 4; i++)
diff --git a/indra/llrender/llglstates.h b/indra/llrender/llglstates.h
index 4a51cac438..968a37cab0 100644
--- a/indra/llrender/llglstates.h
+++ b/indra/llrender/llglstates.h
@@ -46,6 +46,8 @@ public:
 	
 	~LLGLDepthTest();
 	
+	void checkState();
+
 	GLboolean mPrevDepthEnabled;
 	GLenum mPrevDepthFunc;
 	GLboolean mPrevWriteEnabled;
diff --git a/indra/llrender/llrender.cpp b/indra/llrender/llrender.cpp
index fc45df8153..f97d81126e 100644
--- a/indra/llrender/llrender.cpp
+++ b/indra/llrender/llrender.cpp
@@ -162,6 +162,8 @@ void LLTexUnit::enable(eTextureType type)
 			disable(); // Force a disable of a previous texture type if it's enabled.
 		}
 		mCurrTexType = type;
+
+		gGL.flush();
 		glEnable(sGLTextureType[type]);
 	}
 }