diff --git a/source/build/src/engine.cpp b/source/build/src/engine.cpp
index 272546915..d26b9b821 100644
--- a/source/build/src/engine.cpp
+++ b/source/build/src/engine.cpp
@@ -2607,7 +2607,6 @@ killsprite:
     {
         GLInterface.EnableBlend(false);
         GLInterface.EnableAlphaTest(true);
-		GLInterface.SetClamp(1+2);
         GLInterface.SetDepthBias(-2, -256);
 
         if (spritesortcnt < numSprites)
@@ -2660,8 +2659,7 @@ killsprite:
             }
         }
 
-		GLInterface.SetClamp(0);
-        int32_t numMaskWalls = maskwallcnt;
+		int32_t numMaskWalls = maskwallcnt;
         maskwallcnt = 0;
         for (i = 0; i < numMaskWalls; i++)
         {
@@ -2703,11 +2701,6 @@ killsprite:
         _equation p1eq   = equation(pos.x, pos.y, dot.x, dot.y);
         _equation p2eq   = equation(pos.x, pos.y, dot2.x, dot2.y);
 
-#ifdef USE_OPENGL
-        if (videoGetRenderMode() == REND_POLYMOST)
-			GLInterface.SetClamp(1+2);
-#endif
-
         i = spritesortcnt;
         while (i)
         {
@@ -2807,8 +2800,7 @@ killsprite:
     }
     renderFinishScene();
 	GLInterface.SetDepthMask(true);
-	GLInterface.SetClamp(0);
-    GLInterface.SetDepthBias(0, 0);
+	GLInterface.SetDepthBias(0, 0);
 }
 
 
diff --git a/source/build/src/mdsprite.cpp b/source/build/src/mdsprite.cpp
index 0197a2c17..2ce91d095 100644
--- a/source/build/src/mdsprite.cpp
+++ b/source/build/src/mdsprite.cpp
@@ -1643,8 +1643,6 @@ static int32_t polymost_md3draw(md3model_t *m, tspriteptr_t tspr)
         k3 = (float)sintable[sext->roll&2047] * (1.f/16384.f);
     }
 
-    int prevClamp = GLInterface.GetClamp();
-	GLInterface.SetClamp(0);
     VSMatrix imat = 0;
     imat.scale(1024, 1024, 1024);
     GLInterface.SetMatrix(Matrix_Model, &imat);
@@ -1795,7 +1793,6 @@ static int32_t polymost_md3draw(md3model_t *m, tspriteptr_t tspr)
 
     GLInterface.SetIdentityMatrix(Matrix_Model);
     GLInterface.SetTinting(-1, 0xffffff, 0xffffff);
-    GLInterface.SetClamp(prevClamp);
     
     globalnoeffect=0;
     return 1;
diff --git a/source/build/src/polymost.cpp b/source/build/src/polymost.cpp
index 602c349fc..f06e2a07b 100644
--- a/source/build/src/polymost.cpp
+++ b/source/build/src/polymost.cpp
@@ -1828,8 +1828,6 @@ static void polymost_flatskyrender(vec2f_t const* const dpxy, int32_t const n, i
     int const npot = (1<<(widthBits(globalpicnum))) != tileWidth(globalpicnum);
     int const xpanning = (hw_parallaxskypanning?global_cf_xpanning:0);
 
-	GLInterface.SetClamp((npot || xpanning != 0) ? 0 : 2);
-
     int picnumbak = globalpicnum;
     ti = globalpicnum;
     o.y = fviewingrange/(ghalfx*256.f); o.z = 1.f/o.y;
@@ -1967,8 +1965,6 @@ static void polymost_flatskyrender(vec2f_t const* const dpxy, int32_t const n, i
 
     globalpicnum = picnumbak;
 
-	GLInterface.SetClamp(0);
-
     flatskyrender = 1;
     GLInterface.useMapFog = f;
 }
diff --git a/source/build/src/voxmodel.cpp b/source/build/src/voxmodel.cpp
index f436a2a27..625cfff4b 100644
--- a/source/build/src/voxmodel.cpp
+++ b/source/build/src/voxmodel.cpp
@@ -1134,8 +1134,6 @@ int32_t polymost_voxdraw(voxmodel_t *m, tspriteptr_t const tspr)
 #endif
     const float phack[2] = { 0, 1.f/256.f };
 
-    int prevClamp = GLInterface.GetClamp();
-	GLInterface.SetClamp(0);
 #if 1
     int palId = TRANSLATION(Translation_Remap + curbasepal, globalpal); 
     auto palette = GPalette.TranslationToTable(palId);
@@ -1209,7 +1207,6 @@ int32_t polymost_voxdraw(voxmodel_t *m, tspriteptr_t const tspr)
     }
 
 	GLInterface.Draw(DT_Triangles, qstart, qdone * 6);
-	GLInterface.SetClamp(prevClamp);
     //------------
 	GLInterface.SetCull(Cull_None);
 
diff --git a/source/glbackend/glbackend.cpp b/source/glbackend/glbackend.cpp
index 60eb58320..4ba6f4cf8 100644
--- a/source/glbackend/glbackend.cpp
+++ b/source/glbackend/glbackend.cpp
@@ -101,14 +101,6 @@ OpenGLRenderer::FHardwareTexture* GLInstance::NewTexture(int numchannels)
 	return new OpenGLRenderer::FHardwareTexture(numchannels);
 }
 
-void GLInstance::ResetFrame()
-{
-	GLState s;
-	lastState = s; // Back to defaults.
-	lastState.Style.BlendOp = -1;	// invalidate. This forces a reset for the next operation
-
-}
-
 void GLInstance::Draw(EDrawType type, size_t start, size_t count)
 {
 	assert (BufferLock > 0);
@@ -123,12 +115,21 @@ void GLInstance::Draw(EDrawType type, size_t start, size_t count)
 
 void GLInstance::DoDraw()
 {
-	for (auto& rs : rendercommands)
+	GLState lastState;
+
+	if (rendercommands.Size() > 0)
 	{
-		rs.Apply(*screen->RenderState(), lastState);
-		screen->RenderState()->Draw(rs.primtype, rs.vindex, rs.vcount);
+		lastState.Flags = ~rendercommands[0].StateFlags;	// Force ALL flags to be considered 'changed'.
+		lastState.DepthFunc = INT_MIN;						// Something totally invalid.
+
+		for (auto& rs : rendercommands)
+		{
+			rs.Apply(*screen->RenderState(), lastState);
+			screen->RenderState()->Draw(rs.primtype, rs.vindex, rs.vcount);
+		}
+		renderState.Apply(*screen->RenderState(), lastState);	// apply any pending change before returning.
+		rendercommands.Clear();
 	}
-	rendercommands.Clear();
 	matrixArray.Resize(1);
 }
 
@@ -143,7 +144,7 @@ int GLInstance::SetMatrix(int num, const VSMatrix *mat)
 
 void GLInstance::SetIdentityMatrix(int num)
 {
-	renderState.matrixIndex[num] = 0;
+	renderState.matrixIndex[num] = -1;
 }
 
 
@@ -463,7 +464,6 @@ void videoShowFrame(int32_t w)
 	screen->SetSceneRenderTarget(useSSAO);
 	twodpsp.Clear();
 	twod->Clear();
-	GLInterface.ResetFrame();
 }
 
 
diff --git a/source/glbackend/glbackend.h b/source/glbackend/glbackend.h
index 7ea6dba15..6baf52d58 100644
--- a/source/glbackend/glbackend.h
+++ b/source/glbackend/glbackend.h
@@ -76,9 +76,8 @@ enum
 
 struct GLState
 {
-	int Flags = STF_COLORMASK | STF_DEPTHMASK;
-	FRenderStyle Style{};
-	int DepthFunc = -1;
+	int Flags;
+	int DepthFunc;
 };
 
 class GLInstance
@@ -91,9 +90,6 @@ public:
 	FGameTexture* currentTexture = nullptr;
 	int MatrixChange = 0;
 
-	// Cached GL state.
-	GLState lastState;
-
 	PolymostRenderState renderState;
 	
 	
@@ -103,8 +99,7 @@ public:
 	
 	void Init(int y);
 	void InitGLState(int fogmode, int multisample);
-	void ResetFrame();
-
+	
 	void Deinit();
 	
 	static int GetTexDimension(int value)
@@ -154,18 +149,6 @@ public:
 
 	void SetPalswap(int index);
 
-	int GetClamp()
-	{
-		return 0;// int(renderState.Clamp[0] + 2 * renderState.Clamp[1]);
-	}
-
-	void SetClamp(int clamp)
-	{
-		// This option is totally pointless and should be removed.
-		//renderState.Clamp[0] = clamp & 1;
-		//renderState.Clamp[1] = !!(clamp & 2);
-	}
-
 	void SetShade(int32_t shade, int numshades)
 	{
 		renderState.Shade = clamp(shade, 0, numshades-1);
diff --git a/source/glbackend/pm_renderstate.h b/source/glbackend/pm_renderstate.h
index b890489ac..b83203285 100644
--- a/source/glbackend/pm_renderstate.h
+++ b/source/glbackend/pm_renderstate.h
@@ -57,7 +57,7 @@ struct PolymostRenderState
     float AlphaThreshold = 0.5f;
 	bool AlphaTest = true;
 	float Color[4] = { 1,1,1,1 };
-	short matrixIndex[NUMMATRICES] = { 0 };
+	short matrixIndex[NUMMATRICES] = { -1 };
 	PalEntry fullscreenTint = 0xffffff, hictint = 0xffffff, hictint_overlay = 0xffffff;
 	int hictint_flags = -1;
 	FDepthBiasState mBias{ };