diff --git a/src/g_shared/sbarinfo_commands.cpp b/src/g_shared/sbarinfo_commands.cpp
index 13c98d8339..d105ab8180 100644
--- a/src/g_shared/sbarinfo_commands.cpp
+++ b/src/g_shared/sbarinfo_commands.cpp
@@ -1187,12 +1187,12 @@ class CommandDrawNumber : public CommandDrawString
 
 							if (!(cvartype == CVAR_Bool || cvartype == CVAR_Int))
 							{
-								sc.ScriptMessage("CVar '%s' is not an int or bool", cvarName);
+								sc.ScriptMessage("CVar '%s' is not an int or bool", cvarName.GetChars());
 							}
 						}
 						else
 						{
-							sc.ScriptMessage("CVar '%s' does not exist", cvarName);
+							sc.ScriptMessage("CVar '%s' does not exist", cvarName.GetChars());
 						}
 						
 						if (parenthesized) sc.MustGetToken(')');
diff --git a/src/gl/data/gl_matrix.cpp b/src/gl/data/gl_matrix.cpp
index d8017ad404..1158828571 100644
--- a/src/gl/data/gl_matrix.cpp
+++ b/src/gl/data/gl_matrix.cpp
@@ -442,7 +442,7 @@ VSMatrix::computeNormalMatrix(const FLOATTYPE *aMatrix)
 		  mMat3x3[1] * (mMat3x3[5] * mMat3x3[6] - mMat3x3[8] * mMat3x3[3]) +
 		  mMat3x3[2] * (mMat3x3[3] * mMat3x3[7] - mMat3x3[4] * mMat3x3[6]);
 
-	invDet = 1.0f/det;
+	invDet = 1.0/det;
 
 	mMatrix[0] = (mMat3x3[4] * mMat3x3[8] - mMat3x3[5] * mMat3x3[7]) * invDet;
 	mMatrix[1] = (mMat3x3[5] * mMat3x3[6] - mMat3x3[8] * mMat3x3[3]) * invDet;
diff --git a/src/gl/data/gl_vertexbuffer.cpp b/src/gl/data/gl_vertexbuffer.cpp
index 4e76b51cb3..d14599eb8c 100644
--- a/src/gl/data/gl_vertexbuffer.cpp
+++ b/src/gl/data/gl_vertexbuffer.cpp
@@ -71,6 +71,7 @@ void FSimpleVertexBuffer::BindVBO()
 		glEnableVertexAttribArray(VATTR_TEXCOORD);
 		glEnableVertexAttribArray(VATTR_COLOR);
 		glDisableVertexAttribArray(VATTR_VERTEX2);
+		glDisableVertexAttribArray(VATTR_NORMAL);
 	}
 	else
 	{
@@ -236,6 +237,7 @@ void FFlatVertexBuffer::BindVBO()
 		glEnableVertexAttribArray(VATTR_TEXCOORD);
 		glDisableVertexAttribArray(VATTR_COLOR);
 		glDisableVertexAttribArray(VATTR_VERTEX2);
+		glDisableVertexAttribArray(VATTR_NORMAL);
 	}
 	else
 	{
diff --git a/src/gl/data/gl_vertexbuffer.h b/src/gl/data/gl_vertexbuffer.h
index 596de35d9d..f777118fd4 100644
--- a/src/gl/data/gl_vertexbuffer.h
+++ b/src/gl/data/gl_vertexbuffer.h
@@ -271,6 +271,7 @@ struct FModelVertex
 {
 	float x, y, z;	// world position
 	float u, v;		// texture coordinates
+	unsigned packedNormal;	// normal vector as GL_INT_2_10_10_10_REV.
 
 	void Set(float xx, float yy, float zz, float uu, float vv)
 	{
@@ -283,7 +284,13 @@ struct FModelVertex
 
 	void SetNormal(float nx, float ny, float nz)
 	{
-		// GZDoom currently doesn't use normals. This function is so that the high level code can pretend it does.
+	/*
+		int inx = int(nx * 512);
+		int iny = int(ny * 512);
+		int inz = int(nz * 512);
+		packedNormal = 0x40000000 | ((inx & 1023) << 20) | ((iny & 1023) << 10) | (inz & 1023);
+	*/
+		packedNormal = 0;	// Per-pixel lighting for models isn't implemented yet so leave this at 0 for now.
 	}
 };
 
diff --git a/src/gl/dynlights/a_dynlight.cpp b/src/gl/dynlights/a_dynlight.cpp
index 20d0d60782..0e52eedd8a 100644
--- a/src/gl/dynlights/a_dynlight.cpp
+++ b/src/gl/dynlights/a_dynlight.cpp
@@ -391,6 +391,16 @@ void ADynamicLight::UpdateLocation()
 			Prev = target->Pos();
 			subsector = R_PointInSubsector(Prev);
 			Sector = subsector->sector;
+
+			// Some z-coordinate fudging to prevent the light from getting too close to the floor or ceiling planes. With proper attenuation this would render them invisible.
+			// A distance of 5 is needed so that the light's effect doesn't become too small.
+			if (Z() < target->floorz + 5.) 	SetZ(target->floorz + 5.);
+			else if (Z() > target->ceilingz - 5.) 	SetZ(target->ceilingz - 5.);
+		}
+		else
+		{
+			if (Z() < floorz + 5.) 	SetZ(floorz + 5.);
+			else if (Z() > ceilingz - 5.) 	SetZ(ceilingz - 5.);
 		}
 
 
diff --git a/src/gl/models/gl_models.cpp b/src/gl/models/gl_models.cpp
index 91bd9131e7..f3dfbd569d 100644
--- a/src/gl/models/gl_models.cpp
+++ b/src/gl/models/gl_models.cpp
@@ -119,6 +119,7 @@ void FModelVertexBuffer::BindVBO()
 		glEnableVertexAttribArray(VATTR_VERTEX);
 		glEnableVertexAttribArray(VATTR_TEXCOORD);
 		glEnableVertexAttribArray(VATTR_VERTEX2);
+		glEnableVertexAttribArray(VATTR_NORMAL);
 		glDisableVertexAttribArray(VATTR_COLOR);
 	}
 	else
@@ -245,6 +246,7 @@ unsigned int FModelVertexBuffer::SetupFrame(unsigned int frame1, unsigned int fr
 			glVertexAttribPointer(VATTR_VERTEX, 3, GL_FLOAT, false, sizeof(FModelVertex), &VMO[frame1].x);
 			glVertexAttribPointer(VATTR_TEXCOORD, 2, GL_FLOAT, false, sizeof(FModelVertex), &VMO[frame1].u);
 			glVertexAttribPointer(VATTR_VERTEX2, 3, GL_FLOAT, false, sizeof(FModelVertex), &VMO[frame2].x);
+			glVertexAttribPointer(VATTR_NORMAL, 4, GL_UNSIGNED_INT_2_10_10_10_REV, false, sizeof(FModelVertex), &VMO[frame2].packedNormal);
 		}
 		else
 		{
diff --git a/src/gl/models/gl_voxels.cpp b/src/gl/models/gl_voxels.cpp
index 6213eb0068..288b1a9db6 100644
--- a/src/gl/models/gl_voxels.cpp
+++ b/src/gl/models/gl_voxels.cpp
@@ -248,6 +248,7 @@ void FVoxelModel::AddFace(int x1, int y1, int z1, int x2, int y2, int z2, int x3
 	FModelVertex vert;
 	unsigned int indx[4];
 
+	vert.packedNormal = 0;	// currently this is not being used for voxels.
 	vert.u = (((col & 15) * 255 / 16) + 7) / 255.f;
 	vert.v = (((col / 16) * 255 / 16) + 7) / 255.f;
 
@@ -271,6 +272,7 @@ void FVoxelModel::AddFace(int x1, int y1, int z1, int x2, int y2, int z2, int x3
 	vert.y = -z3 + PivotZ;
 	indx[3] = AddVertex(vert, check);
 
+
 	mIndices.Push(indx[0]);
 	mIndices.Push(indx[1]);
 	mIndices.Push(indx[3]);
diff --git a/src/gl/renderer/gl_postprocess.cpp b/src/gl/renderer/gl_postprocess.cpp
index d06b948503..fde8da3533 100644
--- a/src/gl/renderer/gl_postprocess.cpp
+++ b/src/gl/renderer/gl_postprocess.cpp
@@ -579,7 +579,7 @@ void FGLRenderer::LensDistortScene()
 		0.0f
 	};
 
-	float aspect = mSceneViewport.width / mSceneViewport.height;
+	float aspect = mSceneViewport.width / (float)mSceneViewport.height;
 
 	// Scale factor to keep sampling within the input texture
 	float r2 = aspect * aspect * 0.25 + 0.25f;
diff --git a/src/gl/renderer/gl_renderer.cpp b/src/gl/renderer/gl_renderer.cpp
index 5fa2de29d2..2895341cc8 100644
--- a/src/gl/renderer/gl_renderer.cpp
+++ b/src/gl/renderer/gl_renderer.cpp
@@ -117,12 +117,12 @@ FGLRenderer::FGLRenderer(OpenGLFrameBuffer *fb)
 	mTonemapPalette = nullptr;
 	mColormapShader = nullptr;
 	mLensShader = nullptr;
-	mFXAAShader = nullptr;
-	mFXAALumaShader = nullptr;
 	mLinearDepthShader = nullptr;
 	mDepthBlurShader = nullptr;
 	mSSAOShader = nullptr;
 	mSSAOCombineShader = nullptr;
+	mFXAAShader = nullptr;
+	mFXAALumaShader = nullptr;
 }
 
 void gl_LoadModels();
@@ -201,11 +201,11 @@ FGLRenderer::~FGLRenderer()
 	}
 	if (mBuffers) delete mBuffers;
 	if (mPresentShader) delete mPresentShader;
-	if (mPresent3dRowShader) delete mPresent3dRowShader;
 	if (mLinearDepthShader) delete mLinearDepthShader;
 	if (mDepthBlurShader) delete mDepthBlurShader;
 	if (mSSAOShader) delete mSSAOShader;
 	if (mSSAOCombineShader) delete mSSAOCombineShader;
+	if (mPresent3dRowShader) delete mPresent3dRowShader;
 	if (mBloomExtractShader) delete mBloomExtractShader;
 	if (mBloomCombineShader) delete mBloomCombineShader;
 	if (mExposureExtractShader) delete mExposureExtractShader;
diff --git a/src/gl/renderer/gl_renderstate.cpp b/src/gl/renderer/gl_renderstate.cpp
index 2cfd739e90..cfaaea3cc0 100644
--- a/src/gl/renderer/gl_renderstate.cpp
+++ b/src/gl/renderer/gl_renderstate.cpp
@@ -142,6 +142,7 @@ bool FRenderState::ApplyShader()
 	}
 
 	glVertexAttrib4fv(VATTR_COLOR, mColor.vec);
+	glVertexAttrib4fv(VATTR_NORMAL, mNormal.vec);
 
 	activeShader->muDesaturation.Set(mDesaturation / 255.f);
 	activeShader->muFogEnabled.Set(fogset);
@@ -271,12 +272,16 @@ bool FRenderState::ApplyShader()
 	if (mModelMatrixEnabled)
 	{
 		mModelMatrix.matrixToGL(activeShader->modelmatrix_index);
+		VSMatrix norm;
+		norm.computeNormalMatrix(mModelMatrix);
+		mNormalModelMatrix.matrixToGL(activeShader->normalmodelmatrix_index);
 		activeShader->currentModelMatrixState = true;
 	}
 	else if (activeShader->currentModelMatrixState)
 	{
 		activeShader->currentModelMatrixState = false;
 		identityMatrix.matrixToGL(activeShader->modelmatrix_index);
+		identityMatrix.matrixToGL(activeShader->normalmodelmatrix_index);
 	}
 	return true;
 }
diff --git a/src/gl/renderer/gl_renderstate.h b/src/gl/renderer/gl_renderstate.h
index 7bec51be04..3276502f12 100644
--- a/src/gl/renderer/gl_renderstate.h
+++ b/src/gl/renderer/gl_renderstate.h
@@ -97,6 +97,7 @@ class FRenderState
 	float mShaderTimer;
 
 	FVertexBuffer *mVertexBuffer, *mCurrentVertexBuffer;
+	FStateVec4 mNormal;
 	FStateVec4 mColor;
 	FStateVec4 mCameraPos;
 	FStateVec4 mGlowTop, mGlowBottom;
@@ -128,6 +129,8 @@ public:
 	VSMatrix mViewMatrix;
 	VSMatrix mModelMatrix;
 	VSMatrix mTextureMatrix;
+	VSMatrix mNormalViewMatrix;
+	VSMatrix mNormalModelMatrix;
 
 	FRenderState()
 	{
@@ -189,6 +192,16 @@ public:
 
 	void SetClipHeight(float height, float direction);
 
+	void SetNormal(FVector3 norm)
+	{
+		mNormal.Set(norm.X, norm.Y, norm.Z, 0.f);
+	}
+
+	void SetNormal(float x, float y, float z)
+	{
+		mNormal.Set(x, y, z, 0.f);
+	}
+
 	void SetColor(float r, float g, float b, float a = 1.f, int desat = 0)
 	{
 		mColor.Set(r, g, b, a);
diff --git a/src/gl/scene/gl_flats.cpp b/src/gl/scene/gl_flats.cpp
index 90f3be66fc..394ca16265 100644
--- a/src/gl/scene/gl_flats.cpp
+++ b/src/gl/scene/gl_flats.cpp
@@ -374,6 +374,7 @@ void GLFlat::Draw(int pass, bool trans)	// trans only has meaning for GLPASS_LIG
 	}
 #endif
 
+	gl_RenderState.SetNormal(plane.plane.Normal().X, plane.plane.Normal().Z, plane.plane.Normal().Y);
 
 	switch (pass)
 	{
@@ -502,6 +503,11 @@ inline void GLFlat::PutFlat(bool fog)
 void GLFlat::Process(sector_t * model, int whichplane, bool fog)
 {
 	plane.GetFromSector(model, whichplane);
+	if (whichplane != int(ceiling))
+	{
+		// Flip the normal if the source plane has a different orientation than what we are about to render.
+		plane.plane.FlipVert();
+	}
 
 	if (!fog)
 	{
@@ -641,7 +647,7 @@ void GLFlat::ProcessSector(sector_t * frontsector)
 				Colormap.CopyFrom3DLight(light);
 			}
 			renderstyle = STYLE_Translucent;
-			Process(frontsector, false, false);
+			Process(frontsector, sector_t::floor, false);
 		}
 	}
 
@@ -700,7 +706,7 @@ void GLFlat::ProcessSector(sector_t * frontsector)
 				Colormap.CopyFrom3DLight(light);
 			}
 			renderstyle = STYLE_Translucent;
-			Process(frontsector, true, false);
+			Process(frontsector, sector_t::ceiling, false);
 		}
 	}
 
diff --git a/src/gl/scene/gl_portal.cpp b/src/gl/scene/gl_portal.cpp
index f0c9677ba4..02fd9b452b 100644
--- a/src/gl/scene/gl_portal.cpp
+++ b/src/gl/scene/gl_portal.cpp
@@ -1219,7 +1219,7 @@ void GLEEHorizonPortal::DrawContents()
 	if (sector->GetTexture(sector_t::ceiling) != skyflatnum)
 	{
 		GLHorizonInfo horz;
-		horz.plane.GetFromSector(sector, true);
+		horz.plane.GetFromSector(sector, sector_t::ceiling);
 		horz.lightlevel = gl_ClampLight(sector->GetCeilingLight());
 		horz.colormap = sector->ColorMap;
 		if (portal->mType == PORTS_PLANE)
@@ -1232,7 +1232,7 @@ void GLEEHorizonPortal::DrawContents()
 	if (sector->GetTexture(sector_t::floor) != skyflatnum)
 	{
 		GLHorizonInfo horz;
-		horz.plane.GetFromSector(sector, false);
+		horz.plane.GetFromSector(sector, sector_t::floor);
 		horz.lightlevel = gl_ClampLight(sector->GetFloorLight());
 		horz.colormap = sector->ColorMap;
 		if (portal->mType == PORTS_PLANE)
diff --git a/src/gl/scene/gl_skydome.cpp b/src/gl/scene/gl_skydome.cpp
index 1653d2bb84..015b420163 100644
--- a/src/gl/scene/gl_skydome.cpp
+++ b/src/gl/scene/gl_skydome.cpp
@@ -114,6 +114,7 @@ void FSkyVertexBuffer::BindVBO()
 		glEnableVertexAttribArray(VATTR_TEXCOORD);
 		glEnableVertexAttribArray(VATTR_COLOR);
 		glDisableVertexAttribArray(VATTR_VERTEX2);
+		glDisableVertexAttribArray(VATTR_NORMAL);
 	}
 	else
 	{
diff --git a/src/gl/scene/gl_sprite.cpp b/src/gl/scene/gl_sprite.cpp
index 19753f742e..ab88f2f9c7 100644
--- a/src/gl/scene/gl_sprite.cpp
+++ b/src/gl/scene/gl_sprite.cpp
@@ -406,6 +406,7 @@ void GLSprite::Draw(int pass)
 			gl_RenderState.Apply();
 
 			FVector3 v[4];
+			gl_RenderState.SetNormal(0, 0, 0);
 			CalculateVertices(v);
 			
 			FQuadDrawer qd;
diff --git a/src/gl/scene/gl_wall.h b/src/gl/scene/gl_wall.h
index 32dc6ee5b1..143029ba74 100644
--- a/src/gl/scene/gl_wall.h
+++ b/src/gl/scene/gl_wall.h
@@ -60,6 +60,15 @@ struct GLSeg
 	float x1,x2;
 	float y1,y2;
 	float fracleft, fracright;	// fractional offset of the 2 vertices on the linedef
+
+	FVector3 Normal() const 
+	{
+		// we do not use the vector math inlines here because they are not optimized for speed but accuracy in the playsim
+		float x = y2 - y1;
+		float y = x1 - x2;
+		float length = sqrt(x*x + y*y);
+		return FVector3(x / length, 0, y / length);
+	}
 };
 
 struct texcoord
diff --git a/src/gl/scene/gl_walls.cpp b/src/gl/scene/gl_walls.cpp
index 3a7baec332..db16a941af 100644
--- a/src/gl/scene/gl_walls.cpp
+++ b/src/gl/scene/gl_walls.cpp
@@ -470,7 +470,7 @@ bool GLWall::DoHorizon(seg_t * seg,sector_t * fs, vertex_t * v1,vertex_t * v2)
 		}
 		else
 		{
-			hi.plane.GetFromSector(fs, true);
+			hi.plane.GetFromSector(fs, sector_t::ceiling);
 			hi.lightlevel = gl_ClampLight(fs->GetCeilingLight());
 			hi.colormap = fs->ColorMap;
 
@@ -498,7 +498,7 @@ bool GLWall::DoHorizon(seg_t * seg,sector_t * fs, vertex_t * v1,vertex_t * v2)
 		}
 		else
 		{
-			hi.plane.GetFromSector(fs, false);
+			hi.plane.GetFromSector(fs, sector_t::floor);
 			hi.lightlevel = gl_ClampLight(fs->GetFloorLight());
 			hi.colormap = fs->ColorMap;
 
diff --git a/src/gl/scene/gl_walls_draw.cpp b/src/gl/scene/gl_walls_draw.cpp
index a7884b51a6..dbc43fd22b 100644
--- a/src/gl/scene/gl_walls_draw.cpp
+++ b/src/gl/scene/gl_walls_draw.cpp
@@ -254,14 +254,13 @@ void GLWall::RenderMirrorSurface()
 	if (GLRenderer->mirrortexture == NULL) return;
 
 	// For the sphere map effect we need a normal of the mirror surface,
-	Vector v(glseg.y2-glseg.y1, 0 ,-glseg.x2+glseg.x1);
-	v.Normalize();
+	FVector3 v = glseg.Normal();
 
 	if (!gl.legacyMode)
 	{
 		// we use texture coordinates and texture matrix to pass the normal stuff to the shader so that the default vertex buffer format can be used as is.
-		tcs[LOLFT].u = tcs[LORGT].u = tcs[UPLFT].u = tcs[UPRGT].u = v.X();
-		tcs[LOLFT].v = tcs[LORGT].v = tcs[UPLFT].v = tcs[UPRGT].v = v.Z();
+		tcs[LOLFT].u = tcs[LORGT].u = tcs[UPLFT].u = tcs[UPRGT].u = v.X;
+		tcs[LOLFT].v = tcs[LORGT].v = tcs[UPLFT].v = tcs[UPRGT].v = v.Z;
 
 		gl_RenderState.EnableTextureMatrix(true);
 		gl_RenderState.mTextureMatrix.computeNormalMatrix(gl_RenderState.mViewMatrix);
@@ -414,6 +413,7 @@ void GLWall::RenderTranslucentWall()
 //==========================================================================
 void GLWall::Draw(int pass)
 {
+	gl_RenderState.SetNormal(glseg.Normal());
 	switch (pass)
 	{
 	case GLPASS_LIGHTSONLY:
diff --git a/src/gl/shaders/gl_shader.cpp b/src/gl/shaders/gl_shader.cpp
index 26a449bf22..9368a268cb 100644
--- a/src/gl/shaders/gl_shader.cpp
+++ b/src/gl/shaders/gl_shader.cpp
@@ -179,6 +179,7 @@ bool FShader::Load(const char * name, const char * vert_prog_lump, const char *
 	glBindAttribLocation(hShader, VATTR_TEXCOORD, "aTexCoord");
 	glBindAttribLocation(hShader, VATTR_COLOR, "aColor");
 	glBindAttribLocation(hShader, VATTR_VERTEX2, "aVertex2");
+	glBindAttribLocation(hShader, VATTR_NORMAL, "aNormal");
 
 	glBindFragDataLocation(hShader, 0, "FragColor");
 	glBindFragDataLocation(hShader, 1, "FragData");
@@ -245,6 +246,8 @@ bool FShader::Load(const char * name, const char * vert_prog_lump, const char *
 	texturematrix_index = glGetUniformLocation(hShader, "TextureMatrix");
 	vertexmatrix_index = glGetUniformLocation(hShader, "uQuadVertices");
 	texcoordmatrix_index = glGetUniformLocation(hShader, "uQuadTexCoords");
+	normalviewmatrix_index = glGetUniformLocation(hShader, "NormalViewMatrix");
+	normalmodelmatrix_index = glGetUniformLocation(hShader, "NormalModelMatrix");
 	quadmode_index = glGetUniformLocation(hShader, "uQuadMode");
 
 	if (!gl.legacyMode && !(gl.flags & RFL_SHADER_STORAGE_BUFFER))
@@ -333,14 +336,14 @@ FShader *FShaderCollection::Compile (const char *ShaderName, const char *ShaderP
 //
 //==========================================================================
 
-void FShader::ApplyMatrices(VSMatrix *proj, VSMatrix *view)
+void FShader::ApplyMatrices(VSMatrix *proj, VSMatrix *view, VSMatrix *norm)
 {
 	Bind();
 	glUniformMatrix4fv(projectionmatrix_index, 1, false, proj->get());
 	glUniformMatrix4fv(viewmatrix_index, 1, false, view->get());
+	glUniformMatrix4fv(normalviewmatrix_index, 1, false, norm->get());
 }
 
-
 //==========================================================================
 //
 //
@@ -602,23 +605,26 @@ EXTERN_CVAR(Int, gl_fuzztype)
 
 void FShaderCollection::ApplyMatrices(VSMatrix *proj, VSMatrix *view)
 {
+	VSMatrix norm;
+	norm.computeNormalMatrix(*view);
+
 	for (int i = 0; i < 4; i++)
 	{
-		mTextureEffects[i]->ApplyMatrices(proj, view);
-		mTextureEffectsNAT[i]->ApplyMatrices(proj, view);
+		mTextureEffects[i]->ApplyMatrices(proj, view, &norm);
+		mTextureEffectsNAT[i]->ApplyMatrices(proj, view, &norm);
 	}
-	mTextureEffects[4]->ApplyMatrices(proj, view);
+	mTextureEffects[4]->ApplyMatrices(proj, view, &norm);
 	if (gl_fuzztype != 0)
 	{
-		mTextureEffects[4 + gl_fuzztype]->ApplyMatrices(proj, view);
+		mTextureEffects[4 + gl_fuzztype]->ApplyMatrices(proj, view, &norm);
 	}
 	for (unsigned i = 12; i < mTextureEffects.Size(); i++)
 	{
-		mTextureEffects[i]->ApplyMatrices(proj, view);
+		mTextureEffects[i]->ApplyMatrices(proj, view, &norm);
 	}
 	for (int i = 0; i < MAX_EFFECTS; i++)
 	{
-		mEffectShaders[i]->ApplyMatrices(proj, view);
+		mEffectShaders[i]->ApplyMatrices(proj, view, &norm);
 	}
 }
 
diff --git a/src/gl/shaders/gl_shader.h b/src/gl/shaders/gl_shader.h
index 793fa63dd1..934674cbeb 100644
--- a/src/gl/shaders/gl_shader.h
+++ b/src/gl/shaders/gl_shader.h
@@ -287,7 +287,9 @@ class FShader
 	int lights_index;
 	int projectionmatrix_index;
 	int viewmatrix_index;
+	int normalviewmatrix_index;
 	int modelmatrix_index;
+	int normalmodelmatrix_index;
 	int texturematrix_index;
 public:
 	int vertexmatrix_index;
@@ -320,7 +322,7 @@ public:
 	bool Bind();
 	unsigned int GetHandle() const { return hShader; }
 
-	void ApplyMatrices(VSMatrix *proj, VSMatrix *view);
+	void ApplyMatrices(VSMatrix *proj, VSMatrix *view, VSMatrix *norm);
 
 };
 
diff --git a/src/gl/stereo3d/gl_interleaved3d.cpp b/src/gl/stereo3d/gl_interleaved3d.cpp
index 329dec9530..036a84b0b8 100644
--- a/src/gl/stereo3d/gl_interleaved3d.cpp
+++ b/src/gl/stereo3d/gl_interleaved3d.cpp
@@ -104,10 +104,13 @@ void RowInterleaved3D::Present() const
 	// Compute absolute offset from top of screen to top of current display window
 	// because we need screen-relative, not window-relative, scan line parity
 	int windowVOffset = 0;
+	
+#ifdef _WIN32
 	if (! fullscreen) {
 		I_SaveWindowedPos(); // update win_y CVAR
 		windowVOffset = win_y;
 	}
+#endif // _WIN32
 
 	GLRenderer->mPresent3dRowShader->VerticalPixelOffset.Set(
 		windowVOffset // fixme: vary with window location
diff --git a/src/vectors.h b/src/vectors.h
index 00a65df507..1852609f2a 100644
--- a/src/vectors.h
+++ b/src/vectors.h
@@ -556,17 +556,29 @@ struct TVector3
 	// Resizes this vector to be the specified length (if it is not 0)
 	TVector3 &MakeResize(double len)
 	{
-		double scale = len / Length();
-		X = vec_t(X * scale);
-		Y = vec_t(Y * scale);
-		Z = vec_t(Z * scale);
+		double vlen = Length();
+		if (vlen != 0.)
+		{
+			double scale = len / vlen;
+			X = vec_t(X * scale);
+			Y = vec_t(Y * scale);
+			Z = vec_t(Z * scale);
+		}
 		return *this;
 	}
 
 	TVector3 Resized(double len)
 	{
-		double scale = len / Length();
-		return{ vec_t(X * scale), vec_t(Y * scale), vec_t(Z * scale) };
+		double vlen = Length();
+		if (vlen != 0.)
+		{
+			double scale = len / vlen;
+			return{ vec_t(X * scale), vec_t(Y * scale), vec_t(Z * scale) };
+		}
+		else
+		{
+			return *this;
+		}
 	}
 
 	// Dot product
diff --git a/wadsrc/static/language.enu b/wadsrc/static/language.enu
index f29c9301c7..89b38329cf 100644
--- a/wadsrc/static/language.enu
+++ b/wadsrc/static/language.enu
@@ -2638,9 +2638,9 @@ GLPREFMNU_MULTISAMPLE			= "Multisample";
 GLPREFMNU_TONEMAP				= "Tonemap Mode";
 GLPREFMNU_BLOOM					= "Bloom effect";
 GLPREFMNU_LENS					= "Lens distortion effect";
-GLPREFMNU_FXAA					= "FXAA Quality";
 GLPREFMNU_SSAO					= "Ambient occlusion quality";
 GLPREFMNU_SSAO_PORTALS			= "Portals with AO";
+GLPREFMNU_FXAA					= "FXAA Quality";
 
 // Option Values
 OPTVAL_SMART 				= "Smart";
diff --git a/wadsrc/static/menudef.zz b/wadsrc/static/menudef.zz
index df01762691..6eb56be948 100644
--- a/wadsrc/static/menudef.zz
+++ b/wadsrc/static/menudef.zz
@@ -49,6 +49,14 @@ OptionValue "TonemapModes"
 	5, "$OPTVAL_PALETTE"
 }
 
+OptionValue "SSAOModes"
+{
+	0, "$OPTVAL_OFF"
+	1, "$OPTVAL_LOW"
+	2, "$OPTVAL_MEDIUM"
+	3, "$OPTVAL_HIGH"
+}
+
 OptionValue "FXAAQuality"
 {
 	0, "$OPTVAL_OFF"
@@ -58,14 +66,6 @@ OptionValue "FXAAQuality"
 	4, "$OPTVAL_EXTREME"
 }
 
-OptionValue "SSAOModes"
-{
-	0, "$OPTVAL_OFF"
-	1, "$OPTVAL_LOW"
-	2, "$OPTVAL_MEDIUM"
-	3, "$OPTVAL_HIGH"
-}
-
 OptionValue "TextureFormats"
 {
 	0, "$OPTVAL_RGBA8"
@@ -253,7 +253,7 @@ OptionMenu "GLPrefOptions"
 	Option "$GLPREFMNU_TONEMAP", 				gl_tonemap,						"TonemapModes"
 	Option "$GLPREFMNU_BLOOM",		 			gl_bloom,						"OnOff"
 	Option "$GLPREFMNU_LENS",		 			gl_lens,						"OnOff"
-	Option "$GLPREFMNU_FXAA",		 			gl_fxaa,						"FXAAQuality"
 	Option "$GLPREFMNU_SSAO",		 			gl_ssao,						"SSAOModes"
 	Slider "$GLPREFMNU_SSAO_PORTALS",			gl_ssao_portals,				0.0, 4.0, 1.0, 0
+	Option "$GLPREFMNU_FXAA",		 			gl_fxaa,						"FXAAQuality"
 }
diff --git a/wadsrc/static/shaders/glsl/main.fp b/wadsrc/static/shaders/glsl/main.fp
index cdd6ffe3f0..374edb59c0 100644
--- a/wadsrc/static/shaders/glsl/main.fp
+++ b/wadsrc/static/shaders/glsl/main.fp
@@ -1,6 +1,8 @@
 in vec4 pixelpos;
 in vec2 glowdist;
 
+in vec4 vWorldNormal;
+in vec4 vEyeNormal;
 in vec4 vTexCoord;
 in vec4 vColor;
 
@@ -206,6 +208,37 @@ float R_DoomLightingEquation(float light)
 	return lightscale;
 }
 
+//===========================================================================
+//
+// Standard lambertian diffuse light calculation
+//
+//===========================================================================
+
+float diffuseContribution(vec3 lightDirection, vec3 normal)
+{
+	return max(dot(normal, lightDirection), 0.0f);
+}
+
+//===========================================================================
+//
+// Calculates the brightness of a dynamic point light
+// Todo: Find a better way to define which lighting model to use.
+// (Specular mode has been removed for now.)
+//
+//===========================================================================
+
+float pointLightAttenuation(vec4 lightpos)
+{
+	float attenuation = max(lightpos.w - distance(pixelpos.xyz, lightpos.xyz),0.0) / lightpos.w;
+	#if 0
+		return attenuation;
+	#else
+		vec3 lightDirection = normalize(lightpos.xyz - pixelpos.xyz);
+		float diffuseAmount = diffuseContribution(lightDirection, normalize(vWorldNormal.xyz));
+		return attenuation * diffuseAmount;
+	#endif
+}
+
 //===========================================================================
 //
 // Calculate light
@@ -291,7 +324,7 @@ vec4 getLightColor(float fogdist, float fogfactor)
 			{
 				vec4 lightpos = lights[i];
 				vec4 lightcolor = lights[i+1];
-
+				
 				lightcolor.rgb *= pointLightAttenuation(lightpos);
 				dynlight.rgb -= lightcolor.rgb;
 			}
diff --git a/wadsrc/static/shaders/glsl/main.vp b/wadsrc/static/shaders/glsl/main.vp
index 27faafb86e..0baca31f92 100644
--- a/wadsrc/static/shaders/glsl/main.vp
+++ b/wadsrc/static/shaders/glsl/main.vp
@@ -4,8 +4,12 @@ in vec2 aTexCoord;
 in vec4 aColor;
 #ifndef SIMPLE	// we do not need these for simple shaders
 in vec4 aVertex2;
+in vec4 aNormal;
 out vec4 pixelpos;
 out vec2 glowdist;
+
+out vec4 vWorldNormal;
+out vec4 vEyeNormal;
 #endif
 
 out vec4 vTexCoord;
@@ -54,6 +58,9 @@ void main()
 			gl_ClipDistance[3] = -((uSplitTopPlane.w + uSplitTopPlane.x * worldcoord.x + uSplitTopPlane.y * worldcoord.z) * uSplitTopPlane.z) - worldcoord.y;
 			gl_ClipDistance[4] = worldcoord.y + ((uSplitBottomPlane.w + uSplitBottomPlane.x * worldcoord.x + uSplitBottomPlane.y * worldcoord.z) * uSplitBottomPlane.z);
 		}
+
+		vWorldNormal = NormalModelMatrix * aNormal;
+		vEyeNormal = NormalViewMatrix * vWorldNormal;
 	#endif
 	
 	#ifdef SPHEREMAP
diff --git a/wadsrc/static/shaders/glsl/shaderdefs.i b/wadsrc/static/shaders/glsl/shaderdefs.i
index 0f0545b2d9..81edd7b046 100644
--- a/wadsrc/static/shaders/glsl/shaderdefs.i
+++ b/wadsrc/static/shaders/glsl/shaderdefs.i
@@ -57,5 +57,7 @@ uniform int uQuadMode;
 uniform mat4 ProjectionMatrix;
 uniform mat4 ViewMatrix;
 uniform mat4 ModelMatrix;
+uniform mat4 NormalViewMatrix;
+uniform mat4 NormalModelMatrix;
 uniform mat4 TextureMatrix;