diff --git a/.gitignore b/.gitignore
index 094a390e7a..c725789157 100644
--- a/.gitignore
+++ b/.gitignore
@@ -56,3 +56,4 @@
 /mapfiles_release/*.map
 .DS_Store
 /build_vc2017-32
+/build2
diff --git a/src/gl/renderer/gl_renderstate.cpp b/src/gl/renderer/gl_renderstate.cpp
index 76e8ba892e..883231bc49 100644
--- a/src/gl/renderer/gl_renderstate.cpp
+++ b/src/gl/renderer/gl_renderstate.cpp
@@ -436,22 +436,29 @@ void FGLRenderState::SetDepthRange(float min, float max)
 	glDepthRange(min, max);
 }
 
+void FGLRenderState::SetColorMask(bool r, bool g, bool b, bool a)
+{
+	glColorMask(r, g, b, a);
+}
+
 void FGLRenderState::EnableDrawBufferAttachments(bool on)
 {
 	EnableDrawBuffers(on ? GetPassDrawBufferCount() : 1);
 }
 
-void FGLRenderState::SetStencil(int offs, int op, int flags)
+void FGLRenderState::SetStencil(int offs, int op, int flags = -1)
 {
 	static int op2gl[] = { GL_KEEP, GL_INCR, GL_DECR };
 
 	glStencilFunc(GL_EQUAL, screen->stencilValue + offs, ~0);		// draw sky into stencil
 	glStencilOp(GL_KEEP, GL_KEEP, op2gl[op]);		// this stage doesn't modify the stencil
 
-	bool cmon = !(flags & SF_ColorMaskOff);
-	bool cmalpha = cmon || (flags & SF_ColorMaskAlpha);
-	glColorMask(cmon, cmon, cmon, cmalpha);						// don't write to the graphics buffer
-	glDepthMask(!(flags & SF_DepthMaskOff));
+	if (flags != -1)
+	{
+		bool cmon = !(flags & SF_ColorMaskOff);
+		glColorMask(cmon, cmon, cmon, cmon);						// don't write to the graphics buffer
+		glDepthMask(!(flags & SF_DepthMaskOff));
+	}
 }
 
 void FGLRenderState::ToggleState(int state, bool on)
diff --git a/src/gl/renderer/gl_renderstate.h b/src/gl/renderer/gl_renderstate.h
index 7f6ac8af1b..25b4420f38 100644
--- a/src/gl/renderer/gl_renderstate.h
+++ b/src/gl/renderer/gl_renderstate.h
@@ -153,6 +153,7 @@ public:
 	void SetDepthMask(bool on) override;
 	void SetDepthFunc(int func) override;
 	void SetDepthRange(float min, float max) override;
+	void SetColorMask(bool r, bool g, bool b, bool a) override;
 	void EnableDrawBufferAttachments(bool on) override;
 	void SetStencil(int offs, int op, int flags) override;
 	void SetCulling(int mode) override;
diff --git a/src/hwrenderer/scene/hw_drawinfo.cpp b/src/hwrenderer/scene/hw_drawinfo.cpp
index 803b70c121..f3fbbff37a 100644
--- a/src/hwrenderer/scene/hw_drawinfo.cpp
+++ b/src/hwrenderer/scene/hw_drawinfo.cpp
@@ -667,10 +667,10 @@ void HWDrawInfo::AddSubsectorToPortal(FSectorPortalGroup *ptg, subsector_t *sub)
 	auto portal = FindPortal(ptg);
 	if (!portal)
 	{
-		portal = new HWScenePortal(screen->mPortalState, new HWSectorStackPortal(ptg));
+        portal = new HWSectorStackPortal(screen->mPortalState, ptg);
 		Portals.Push(portal);
 	}
-	auto ptl = static_cast<HWSectorStackPortal*>(static_cast<HWScenePortal*>(portal)->mScene);
+    auto ptl = static_cast<HWSectorStackPortal*>(portal);
 	ptl->AddSubsector(sub);
 }
 
diff --git a/src/hwrenderer/scene/hw_drawinfo.h b/src/hwrenderer/scene/hw_drawinfo.h
index 24d6c22180..5913ca97bf 100644
--- a/src/hwrenderer/scene/hw_drawinfo.h
+++ b/src/hwrenderer/scene/hw_drawinfo.h
@@ -144,7 +144,7 @@ struct HWDrawInfo
 	HWDrawInfo * outer = nullptr;
 	int FullbrightFlags;
 	std::atomic<int> spriteindex;
-	HWScenePortalBase *mClipPortal;
+	HWPortal *mClipPortal;
 	HWPortal *mCurrentPortal;
 	//FRotator mAngles;
 	Clipper *mClipper;
diff --git a/src/hwrenderer/scene/hw_drawstructs.h b/src/hwrenderer/scene/hw_drawstructs.h
index d500e67957..ae89d65de9 100644
--- a/src/hwrenderer/scene/hw_drawstructs.h
+++ b/src/hwrenderer/scene/hw_drawstructs.h
@@ -201,7 +201,7 @@ public:
 //private:
 
 	void PutWall(HWDrawInfo *di, bool translucent);
-	void PutPortal(HWDrawInfo *di, int ptype);
+	void PutPortal(HWDrawInfo *di, int ptype, int plane);
 	void CheckTexturePosition(FTexCoordInfo *tci);
 
 	void Put3DWall(HWDrawInfo *di, lightlist_t * lightlist, bool translucent);
diff --git a/src/hwrenderer/scene/hw_portal.cpp b/src/hwrenderer/scene/hw_portal.cpp
index 6426e4213c..9cb35c696c 100644
--- a/src/hwrenderer/scene/hw_portal.cpp
+++ b/src/hwrenderer/scene/hw_portal.cpp
@@ -26,7 +26,6 @@
 */
 
 #include "c_dispatch.h"
-#include "portal.h"
 #include "p_maputl.h"
 #include "hw_portal.h"
 #include "hw_clipper.h"
@@ -141,6 +140,14 @@ bool FPortalSceneState::RenderFirstSkyPortal(int recursion, HWDrawInfo *outer_di
 				best = p;
 				bestindex = i;
 			}
+
+			// If the portal area contains the current camera viewpoint, let's always use it because it's likely to give the largest area.
+			if (p->boundingBox.contains(outer_di->Viewpoint.Pos))
+			{
+				best = p;
+				bestindex = i;
+				break;
+			}
 		}
 	}
 
@@ -172,13 +179,14 @@ void HWPortal::DrawPortalStencil(FRenderState &state, int pass)
 	if (mPrimIndices.Size() == 0)
 	{
 		mPrimIndices.Resize(2 * lines.Size());
-
+		
 		for (unsigned int i = 0; i < lines.Size(); i++)
 		{
 			mPrimIndices[i * 2] = lines[i].vertindex;
 			mPrimIndices[i * 2 + 1] = lines[i].vertcount;
 		}
 	}
+	
 	for (unsigned int i = 0; i < mPrimIndices.Size(); i += 2)
 	{
 		state.Draw(DT_TriangleFan, mPrimIndices[i], mPrimIndices[i + 1], i == 0);
@@ -187,12 +195,32 @@ void HWPortal::DrawPortalStencil(FRenderState &state, int pass)
 	{
 		// The cap's depth handling needs special treatment so that it won't block further portal caps.
 		if (pass == STP_DepthRestore) state.SetDepthRange(1, 1);
-		state.Draw(DT_TriangleFan, FFlatVertexBuffer::STENCILTOP_INDEX, 4);
-		state.Draw(DT_TriangleFan, FFlatVertexBuffer::STENCILBOTTOM_INDEX, 4);
+
+		if (planesused & (1 << sector_t::floor))
+		{
+			auto verts = screen->mVertexData->AllocVertices(4);
+			auto ptr = verts.first;
+			ptr[0].Set((float)boundingBox.left, -32767.f, (float)boundingBox.top, 0, 0);
+			ptr[1].Set((float)boundingBox.right, -32767.f, (float)boundingBox.top, 0, 0);
+			ptr[2].Set((float)boundingBox.left, -32767.f, (float)boundingBox.bottom, 0, 0);
+			ptr[3].Set((float)boundingBox.right, -32767.f, (float)boundingBox.bottom, 0, 0);
+			state.Draw(DT_TriangleStrip, verts.second, 4, false);
+		}
+		if (planesused & (1 << sector_t::ceiling))
+		{
+			auto verts = screen->mVertexData->AllocVertices(4);
+			auto ptr = verts.first;
+			ptr[0].Set((float)boundingBox.left, 32767.f, (float)boundingBox.top, 0, 0);
+			ptr[1].Set((float)boundingBox.right, 32767.f, (float)boundingBox.top, 0, 0);
+			ptr[2].Set((float)boundingBox.left, 32767.f, (float)boundingBox.bottom, 0, 0);
+			ptr[3].Set((float)boundingBox.right, 32767.f, (float)boundingBox.bottom, 0, 0);
+			state.Draw(DT_TriangleStrip, verts.second, 4, false);
+		}
 		if (pass == STP_DepthRestore) state.SetDepthRange(0, 1);
 	}
 }
 
+
 //-----------------------------------------------------------------------------
 //
 // Start
@@ -204,53 +232,60 @@ void HWPortal::SetupStencil(HWDrawInfo *di, FRenderState &state, bool usestencil
 	Clocker c(PortalAll);
 
 	rendered_portals++;
+	
 	if (usestencil)
 	{
-		// Create stencil 
+		// Create stencil
+		state.SetStencil(0, SOP_Increment);	// create stencil, increment stencil of valid pixels
+		state.SetColorMask(false);
 		state.SetEffect(EFF_STENCIL);
 		state.EnableTexture(false);
 		state.ResetColor();
-
+		state.SetDepthFunc(DF_Less);
+			
 		if (NeedDepthBuffer())
 		{
-			state.SetStencil(0, SOP_Increment, SF_ColorMaskOff | SF_DepthMaskOff);
-			state.SetDepthFunc(DF_Less);
+			state.SetDepthMask(false);							// don't write to Z-buffer!
+				
 			DrawPortalStencil(state, STP_Stencil);
-
+				
 			// Clear Z-buffer
-			state.SetStencil(1, SOP_Keep, SF_ColorMaskOff);
+			state.SetStencil(1, SOP_Keep); // draw sky into stencil. This stage doesn't modify the stencil.
+			state.SetDepthMask(true);							// enable z-buffer again
 			state.SetDepthRange(1, 1);
 			state.SetDepthFunc(DF_Always);
 			DrawPortalStencil(state, STP_DepthClear);
-
+				
 			// set normal drawing mode
 			state.EnableTexture(true);
-			state.SetStencil(1, SOP_Keep, SF_AllOn);
 			state.SetDepthRange(0, 1);
 			state.SetDepthFunc(DF_Less);
+			state.SetColorMask(true);
 			state.SetEffect(EFF_NONE);
 		}
 		else
 		{
 			// No z-buffer is needed therefore we can skip all the complicated stuff that is involved
 			// Note: We must draw the stencil with z-write enabled here because there is no second pass!
-			state.SetStencil(0, SOP_Increment, SF_ColorMaskOff);
-			state.SetDepthFunc(DF_Less);
+				
+			state.SetDepthMask(true);
 			DrawPortalStencil(state, STP_AllInOne);
-
-			state.SetStencil(1, SOP_Keep, SF_DepthMaskOff);
-			state.EnableDepthTest(false);
+			state.SetStencil(1, SOP_Keep); // draw sky into stencil. This stage doesn't modify the stencil.
 			state.EnableTexture(true);
+			state.SetColorMask(true);
 			state.SetEffect(EFF_NONE);
+			state.EnableDepthTest(false);
+			state.SetDepthMask(false);							// don't write to Z-buffer!
 		}
-
 		screen->stencilValue++;
+		
+		
 	}
 	else
 	{
 		if (!NeedDepthBuffer())
 		{
-			state.SetStencil(0, SOP_Keep, SF_DepthMaskOff);
+			state.SetDepthMask(false);
 			state.EnableDepthTest(false);
 		}
 	}
@@ -259,6 +294,12 @@ void HWPortal::SetupStencil(HWDrawInfo *di, FRenderState &state, bool usestencil
 	savedvisibility = di->Viewpoint.camera ? di->Viewpoint.camera->renderflags & RF_MAYBEINVISIBLE : ActorRenderFlags::FromInt(0);
 }
 
+
+//-----------------------------------------------------------------------------
+//
+// End
+//
+//-----------------------------------------------------------------------------
 void HWPortal::RemoveStencil(HWDrawInfo *di, FRenderState &state, bool usestencil)
 {
 	Clocker c(PortalAll);
@@ -268,53 +309,73 @@ void HWPortal::RemoveStencil(HWDrawInfo *di, FRenderState &state, bool usestenci
 	auto &vp = di->Viewpoint;
 	if (vp.camera != nullptr) vp.camera->renderflags = (vp.camera->renderflags & ~RF_MAYBEINVISIBLE) | savedvisibility;
 
-	state.EnableDepthTest(true);
 	if (usestencil)
 	{
+		
+		state.SetColorMask(false);						// no graphics
 		state.SetEffect(EFF_NONE);
 		state.ResetColor();
 		state.EnableTexture(false);
-
+		
 		if (needdepth)
 		{
 			// first step: reset the depth buffer to max. depth
-			state.SetStencil(0, SOP_Keep, SF_ColorMaskOff);
 			state.SetDepthRange(1, 1);							// always
 			state.SetDepthFunc(DF_Always);						// write the farthest depth value
 			DrawPortalStencil(state, STP_DepthClear);
 		}
-
+		else
+		{
+			state.EnableDepthTest(true);
+		}
+		
 		// second step: restore the depth buffer to the previous values and reset the stencil
-		state.SetStencil(0, SOP_Decrement, SF_ColorMaskOff);
-		state.SetDepthRange(0, 1);
 		state.SetDepthFunc(DF_LEqual);
+		state.SetDepthRange(0, 1);
+		state.SetStencil(0, SOP_Decrement);
 		DrawPortalStencil(state, STP_DepthRestore);
-
+		state.SetDepthFunc(DF_Less);
+		
+		
 		state.EnableTexture(true);
 		state.SetEffect(EFF_NONE);
+		state.SetColorMask(true);
 		screen->stencilValue--;
+		
+		// restore old stencil op.
+		state.SetStencil(0, SOP_Keep);
 	}
 	else
 	{
+		if (needdepth)
+		{
+			state.Clear(CT_Depth);
+		}
+		else
+		{
+			state.EnableDepthTest(true);
+			state.SetDepthMask(true);
+		}
+		
+		// This draws a valid z-buffer into the stencil's contents to ensure it
+		// doesn't get overwritten by the level's geometry.
+		
 		state.ResetColor();
+		state.SetDepthFunc(DF_LEqual);
+		state.SetDepthRange(0, 1);
+		state.SetColorMask(0, 0, 0, 1); // mark portal in alpha channel but don't touch color
 		state.SetEffect(EFF_STENCIL);
 		state.EnableTexture(false);
 		state.SetRenderStyle(STYLE_Source);
-
-		state.SetStencil(0, SOP_Keep, SF_ColorMaskOff | SF_ColorMaskAlpha);	// SSAO needs the alpha channel as a marker.
-		if (needdepth) state.Clear(CT_Depth);
-		state.SetDepthRange(0, 1);
-		state.SetDepthFunc(DF_LEqual);
 		DrawPortalStencil(state, STP_DepthRestore);
-
 		state.SetEffect(EFF_NONE);
 		state.EnableTexture(true);
+		state.SetColorMask(true);
+		state.SetDepthFunc(DF_Less);
 	}
-	state.SetStencil(0, SOP_Keep, SF_AllOn);
 }
 
 
-
 //-----------------------------------------------------------------------------
 //
 // 
@@ -328,7 +389,6 @@ void HWScenePortalBase::ClearClipper(HWDrawInfo *di, Clipper *clipper)
 
 	clipper->Clear();
 
-	auto &lines = mOwner->lines;
 	// Set the clipper to the minimal visible area
 	clipper->SafeAddClipRange(0, 0xffffffff);
 	for (unsigned int i = 0; i < lines.Size(); i++)
@@ -409,7 +469,7 @@ int HWLinePortal::ClipPoint(const DVector2 &pos)
 
 bool HWMirrorPortal::Setup(HWDrawInfo *di, FRenderState &rstate, Clipper *clipper)
 {
-	auto state = mOwner->mState;
+	auto state = mState;
 	if (state->renderdepth > r_mirror_recursions)
 	{
 		return false;
@@ -490,7 +550,7 @@ bool HWMirrorPortal::Setup(HWDrawInfo *di, FRenderState &rstate, Clipper *clippe
 
 void HWMirrorPortal::Shutdown(HWDrawInfo *di, FRenderState &rstate)
 {
-	mOwner->mState->MirrorFlag--;
+	mState->MirrorFlag--;
 }
 
 const char *HWMirrorPortal::GetName() { return "Mirror"; }
@@ -513,7 +573,7 @@ const char *HWMirrorPortal::GetName() { return "Mirror"; }
 bool HWLineToLinePortal::Setup(HWDrawInfo *di, FRenderState &rstate, Clipper *clipper)
 {
 	// TODO: Handle recursion more intelligently
-	auto &state = mOwner->mState;
+	auto &state = mState;
 	if (state->renderdepth>r_mirror_recursions)
 	{
 		return false;
@@ -543,7 +603,6 @@ bool HWLineToLinePortal::Setup(HWDrawInfo *di, FRenderState &rstate, Clipper *cl
 		}
 	}
 
-	auto &lines = mOwner->lines;
 
 	for (unsigned i = 0; i < lines.Size(); i++)
 	{
@@ -589,10 +648,10 @@ const char *HWLineToLinePortal::GetName() { return "LineToLine"; }
 
 bool HWSkyboxPortal::Setup(HWDrawInfo *di, FRenderState &rstate, Clipper *clipper)
 {
-	auto state = mOwner->mState;
+	auto state = mState;
 	old_pm = state->PlaneMirrorMode;
 
-	if (mOwner->mState->skyboxrecursion >= 3)
+	if (mState->skyboxrecursion >= 3)
 	{
 		return false;
 	}
@@ -631,7 +690,7 @@ void HWSkyboxPortal::Shutdown(HWDrawInfo *di, FRenderState &rstate)
 {
 	rstate.SetDepthClamp(oldclamp);
 
-	auto state = mOwner->mState;
+	auto state = mState;
 	portal->mFlags &= ~PORTSF_INSKYBOX;
 	state->inskybox = false;
 	state->skyboxrecursion--;
@@ -699,7 +758,7 @@ void HWSectorStackPortal::SetupCoverage(HWDrawInfo *di)
 //-----------------------------------------------------------------------------
 bool HWSectorStackPortal::Setup(HWDrawInfo *di, FRenderState &rstate, Clipper *clipper)
 {
-	auto state = mOwner->mState;
+	auto state = mState;
 	FSectorPortalGroup *portal = origin;
 	auto &vp = di->Viewpoint;
 
@@ -751,7 +810,7 @@ const char *HWSectorStackPortal::GetName() { return "Sectorstack"; }
 
 bool HWPlaneMirrorPortal::Setup(HWDrawInfo *di, FRenderState &rstate, Clipper *clipper)
 {
-	auto state = mOwner->mState;
+	auto state = mState;
 	if (state->renderdepth > r_mirror_recursions)
 	{
 		return false;
@@ -781,7 +840,7 @@ bool HWPlaneMirrorPortal::Setup(HWDrawInfo *di, FRenderState &rstate, Clipper *c
 
 void HWPlaneMirrorPortal::Shutdown(HWDrawInfo *di, FRenderState &rstate)
 {
-	auto state = mOwner->mState;
+	auto state = mState;
 	state->PlaneMirrorFlag--;
 	state->PlaneMirrorMode = old_pm;
 	std::swap(screen->instack[sector_t::floor], screen->instack[sector_t::ceiling]);
@@ -800,8 +859,8 @@ const char *HWPlaneMirrorPortal::GetName() { return origin->fC() < 0? "Planemirr
 //-----------------------------------------------------------------------------
 //-----------------------------------------------------------------------------
 
-HWHorizonPortal::HWHorizonPortal(FPortalSceneState *s, GLHorizonInfo * pt, FRenderViewpoint &vp, HWDrawInfo *di, bool local)
-	: HWPortal(s, local)
+HWHorizonPortal::HWHorizonPortal(FPortalSceneState *s, GLHorizonInfo * pt, FRenderViewpoint &vp, bool local)
+: HWPortal(s, local)
 {
 	origin = pt;
 
@@ -960,7 +1019,7 @@ void HWEEHorizonPortal::DrawContents(HWDrawInfo *di, FRenderState &state)
 		{
 			horz.plane.Texheight = vp.Pos.Z + fabs(horz.plane.Texheight);
 		}
-		HWHorizonPortal ceil(mState, &horz, di->Viewpoint, di, true);
+		HWHorizonPortal ceil(mState, &horz, di->Viewpoint, true);
 		ceil.DrawContents(di, state);
 	}
 	if (sector->GetTexture(sector_t::floor) != skyflatnum)
@@ -974,7 +1033,7 @@ void HWEEHorizonPortal::DrawContents(HWDrawInfo *di, FRenderState &state)
 		{
 			horz.plane.Texheight = vp.Pos.Z - fabs(horz.plane.Texheight);
 		}
-		HWHorizonPortal floor(mState, &horz, di->Viewpoint, di, true);
+		HWHorizonPortal floor(mState, &horz, di->Viewpoint, true);
 		floor.DrawContents(di, state);
 	}
 }
diff --git a/src/hwrenderer/scene/hw_portal.h b/src/hwrenderer/scene/hw_portal.h
index 35629b89ab..f9d9e243c6 100644
--- a/src/hwrenderer/scene/hw_portal.h
+++ b/src/hwrenderer/scene/hw_portal.h
@@ -1,13 +1,13 @@
 #pragma once
 
-#include "portal.h"
+#include "tarray.h"
+#include "r_utility.h"
 #include "actor.h"
-#include "hw_drawinfo.h"
-#include "hw_drawstructs.h"
+#include "hwrenderer/scene/hw_drawinfo.h"
+#include "hwrenderer/scene/hw_drawstructs.h"
+#include "hw_renderstate.h"
 #include "hwrenderer/textures/hw_material.h"
-#include "hwrenderer/scene/hw_renderstate.h"
 
-class FSkyVertexBuffer;
 
 struct GLSkyInfo
 {
@@ -61,12 +61,17 @@ class HWPortal
 public:
 	FPortalSceneState * mState;
 	TArray<GLWall> lines;
+	BoundingRect boundingBox;
+	int planesused = 0;
 
-	HWPortal(FPortalSceneState *s, bool local);
-	void SetupStencil(HWDrawInfo *di, FRenderState &state, bool usestencil);
-	void RemoveStencil(HWDrawInfo *di, FRenderState &state, bool usestencil);
-
-	virtual ~HWPortal() {}
+    HWPortal(FPortalSceneState *s, bool local = false) : mState(s), boundingBox(false)
+    {
+    }
+    virtual ~HWPortal() {}
+    virtual int ClipSeg(seg_t *seg, const DVector3 &viewpos) { return PClip_Inside; }
+    virtual int ClipSubsector(subsector_t *sub) { return PClip_Inside; }
+    virtual int ClipPoint(const DVector2 &pos) { return PClip_Inside; }
+    virtual line_t *ClipLine() { return nullptr; }
 	virtual void * GetSource() const = 0;	// GetSource MUST be implemented!
 	virtual const char *GetName() = 0;
 	virtual bool IsSky() { return false; }
@@ -74,15 +79,20 @@ public:
 	virtual bool NeedDepthBuffer() { return true; }
 	virtual void DrawContents(HWDrawInfo *di, FRenderState &state) = 0;
 	virtual void RenderAttached(HWDrawInfo *di) {}
+	void SetupStencil(HWDrawInfo *di, FRenderState &state, bool usestencil);
+	void RemoveStencil(HWDrawInfo *di, FRenderState &state, bool usestencil);
 
 	void AddLine(GLWall * l)
 	{
 		lines.Push(*l);
+		boundingBox.addVertex(l->glseg.x1, l->glseg.y1);
+		boundingBox.addVertex(l->glseg.x2, l->glseg.y2);
 	}
 
 
 };
 
+
 struct FPortalSceneState
 {
 	int MirrorFlag = 0;
@@ -116,37 +126,28 @@ struct FPortalSceneState
 	void RenderPortal(HWPortal *p, FRenderState &state, bool usestencil, HWDrawInfo *outer_di);
 };
 
-inline HWPortal::HWPortal(FPortalSceneState *s, bool local) : mState(s)
-{
-	//if (!local) s->portals.Push(this);
-}
-
-
-class HWScenePortalBase
+    
+class HWScenePortalBase : public HWPortal
 {
 protected:
-	HWPortal *mOwner;
+    HWScenePortalBase(FPortalSceneState *state) : HWPortal(state, false)
+    {
+        
+    }
 public:
-	HWScenePortalBase() {}
-	virtual ~HWScenePortalBase() {}
-	void SetOwner(HWPortal *p) { mOwner = p; }
 	void ClearClipper(HWDrawInfo *di, Clipper *clipper);
-
-	virtual int ClipSeg(seg_t *seg, const DVector3 &viewpos) { return PClip_Inside; }
-	virtual int ClipSubsector(subsector_t *sub) { return PClip_Inside; }
-	virtual int ClipPoint(const DVector2 &pos) { return PClip_Inside; }
-	virtual line_t *ClipLine() { return nullptr; }
-
-	virtual bool IsSky() { return false; }
-	virtual bool NeedCap() { return false; }
 	virtual bool NeedDepthBuffer() { return true; }
-	virtual void * GetSource() const = 0;	// GetSource MUST be implemented!
-	virtual const char *GetName() = 0;
-
+	virtual void DrawContents(HWDrawInfo *di, FRenderState &state)
+	{
+		if (Setup(di, state, di->mClipper))
+		{
+			di->DrawScene(di, DM_PORTAL);
+			Shutdown(di, state);
+		}
+		else state.ClearScreen();
+	}
 	virtual bool Setup(HWDrawInfo *di, FRenderState &rstate, Clipper *clipper) = 0;
 	virtual void Shutdown(HWDrawInfo *di, FRenderState &rstate) {}
-	virtual void RenderAttached(HWDrawInfo *di) {}
-
 };
 
 struct HWLinePortal : public HWScenePortalBase
@@ -157,14 +158,14 @@ struct HWLinePortal : public HWScenePortalBase
 
 	angle_t		angv1, angv2;	// for quick comparisons with a line or subsector
 
-	HWLinePortal(line_t *line)
+	HWLinePortal(FPortalSceneState *state, line_t *line) : HWScenePortalBase(state)
 	{
 		v1 = line->v1;
 		v2 = line->v2;
 		CalcDelta();
 	}
 
-	HWLinePortal(FLinePortalSpan *line)
+	HWLinePortal(FPortalSceneState *state, FLinePortalSpan *line) : HWScenePortalBase(state)
 	{
 		if (line->lines[0]->mType != PORTT_LINKED || line->v1 == nullptr)
 		{
@@ -212,8 +213,8 @@ protected:
 
 public:
 
-	HWMirrorPortal(line_t * line)
-		: HWLinePortal(line)
+	HWMirrorPortal(FPortalSceneState *state, line_t * line)
+		: HWLinePortal(state, line)
 	{
 		linedef = line;
 	}
@@ -232,8 +233,8 @@ protected:
 
 public:
 
-	HWLineToLinePortal(FLinePortalSpan *ll)
-		: HWLinePortal(ll)
+	HWLineToLinePortal(FPortalSceneState *state, FLinePortalSpan *ll)
+		: HWLinePortal(state, ll)
 	{
 		glport = ll;
 	}
@@ -256,7 +257,7 @@ protected:
 public:
 
 
-	HWSkyboxPortal(FSectorPortal * pt)
+	HWSkyboxPortal(FPortalSceneState *state, FSectorPortal * pt) : HWScenePortalBase(state)
 	{
 		portal = pt;
 	}
@@ -277,7 +278,7 @@ protected:
 
 public:
 
-	HWSectorStackPortal(FSectorPortalGroup *pt)
+	HWSectorStackPortal(FPortalSceneState *state, FSectorPortalGroup *pt) : HWScenePortalBase(state)
 	{
 		origin = pt;
 	}
@@ -301,7 +302,7 @@ protected:
 
 public:
 
-	HWPlaneMirrorPortal(secplane_t * pt)
+	HWPlaneMirrorPortal(FPortalSceneState *state, secplane_t * pt) : HWScenePortalBase(state)
 	{
 		origin = pt;
 	}
@@ -309,34 +310,6 @@ public:
 };
 
 
-class HWScenePortal : public HWPortal
-{
-public:
-	HWScenePortalBase *mScene;
-	HWScenePortal(FPortalSceneState *state, HWScenePortalBase *handler) : HWPortal(state, false)
-	{
-		mScene = handler;
-		handler->SetOwner(this);
-	}
-	~HWScenePortal() { delete mScene; }
-	virtual void * GetSource() const { return mScene->GetSource(); }
-	virtual const char *GetName() { return mScene->GetName(); }
-	virtual bool IsSky() { return mScene->IsSky(); }
-	virtual bool NeedCap() { return true; }
-	virtual bool NeedDepthBuffer() { return true; }
-	virtual void DrawContents(HWDrawInfo *di, FRenderState &state)
-	{
-		if (mScene->Setup(di, state, di->mClipper))
-		{
-			di->DrawScene(di, DM_PORTAL);
-			mScene->Shutdown(di, state);
-		}
-		else state.ClearScreen();
-	}
-	virtual void RenderAttached(HWDrawInfo *di) { return mScene->RenderAttached(di); }
-};
-
-
 struct HWHorizonPortal : public HWPortal
 {
 	GLHorizonInfo * origin;
@@ -352,8 +325,8 @@ protected:
 	virtual const char *GetName();
 
 public:
-
-	HWHorizonPortal(FPortalSceneState *state, GLHorizonInfo * pt, FRenderViewpoint &vp, HWDrawInfo *di, bool local = false);
+	
+	HWHorizonPortal(FPortalSceneState *state, GLHorizonInfo * pt, FRenderViewpoint &vp, bool local = false);
 };
 
 struct HWEEHorizonPortal : public HWPortal
@@ -369,7 +342,7 @@ protected:
 
 public:
 
-	HWEEHorizonPortal(FPortalSceneState *state, FSectorPortal *pt, HWDrawInfo *di) : HWPortal(state, false)
+	HWEEHorizonPortal(FPortalSceneState *state, FSectorPortal *pt) : HWPortal(state)
 	{
 		portal = pt;
 	}
diff --git a/src/hwrenderer/scene/hw_renderstate.h b/src/hwrenderer/scene/hw_renderstate.h
index 66f7ccff3f..f494df34a0 100644
--- a/src/hwrenderer/scene/hw_renderstate.h
+++ b/src/hwrenderer/scene/hw_renderstate.h
@@ -57,7 +57,6 @@ enum EStencilFlags
 	SF_AllOn = 0,
 	SF_ColorMaskOff = 1,
 	SF_DepthMaskOff = 2,
-	SF_ColorMaskAlpha = 4,	// hack value for SSAO
 };
 
 enum EStencilOp
@@ -507,8 +506,9 @@ public:
 	virtual void SetDepthMask(bool on) = 0;						// Used by decals and indirectly by portal setup.
 	virtual void SetDepthFunc(int func) = 0;					// Used by models, portals and mirror surfaces.
 	virtual void SetDepthRange(float min, float max) = 0;		// Used by portal setup.
+	virtual void SetColorMask(bool r, bool g, bool b, bool a) = 0;	// Used by portals.
 	virtual void EnableDrawBufferAttachments(bool on) = 0;		// Used by fog boundary drawer.
-	virtual void SetStencil(int offs, int op, int flags) = 0;	// Used by portal setup and render hacks.
+	virtual void SetStencil(int offs, int op, int flags=-1) = 0;	// Used by portal setup and render hacks.
 	virtual void SetCulling(int mode) = 0;						// Used by model drawer only.
 	virtual void EnableClipDistance(int num, bool state) = 0;	// Use by sprite sorter for vertical splits.
 	virtual void Clear(int targets) = 0;						// not used during normal rendering
@@ -519,6 +519,10 @@ public:
 	virtual void EnableMultisampling(bool on) = 0;				// only active for 2D
 	virtual void EnableLineSmooth(bool on) = 0;					// constant setting for each 2D drawer operation
 
+	void SetColorMask(bool on)
+	{
+		SetColorMask(on, on, on, on);
+	}
 
 };
 
diff --git a/src/hwrenderer/scene/hw_sky.cpp b/src/hwrenderer/scene/hw_sky.cpp
index 57eeb0eee3..695321312a 100644
--- a/src/hwrenderer/scene/hw_sky.cpp
+++ b/src/hwrenderer/scene/hw_sky.cpp
@@ -122,7 +122,7 @@ void GLWall::SkyPlane(HWDrawInfo *di, sector_t *sector, int plane, bool allowref
 		skyinfo.init(sector->sky, Colormap.FadeColor);
 		ptype = PORTALTYPE_SKY;
 		sky = &skyinfo;
-		PutPortal(di, ptype);
+		PutPortal(di, ptype, plane);
 	}
 	else if (sportal != nullptr)
 	{
@@ -162,7 +162,7 @@ void GLWall::SkyPlane(HWDrawInfo *di, sector_t *sector, int plane, bool allowref
 	}
 	if (ptype != -1)
 	{
-		PutPortal(di, ptype);
+		PutPortal(di, ptype, plane);
 	}
 }
 
@@ -197,7 +197,7 @@ void GLWall::SkyLine(HWDrawInfo *di, sector_t *fs, line_t *line)
 	ztop[1] = zceil[1];
 	zbottom[0] = zfloor[0];
 	zbottom[1] = zfloor[1];
-	PutPortal(di, ptype);
+	PutPortal(di, ptype, -1);
 }
 
 
diff --git a/src/hwrenderer/scene/hw_skyportal.cpp b/src/hwrenderer/scene/hw_skyportal.cpp
index 9da564e635..cb04c1e866 100644
--- a/src/hwrenderer/scene/hw_skyportal.cpp
+++ b/src/hwrenderer/scene/hw_skyportal.cpp
@@ -104,9 +104,9 @@ void HWSkyPortal::RenderBox(HWDrawInfo *di, FRenderState &state, FTextureID texn
 	state.mModelMatrix.loadIdentity();
 
 	if (!sky2)
-		state.mModelMatrix.rotate(-180.0f+x_offset, level.info->skyrotatevector.X, level.info->skyrotatevector.Z, level.info->skyrotatevector.Y);
+        state.mModelMatrix.rotate(-180.0f+x_offset, ::level.info->skyrotatevector.X, ::level.info->skyrotatevector.Z, ::level.info->skyrotatevector.Y);
 	else
-		state.mModelMatrix.rotate(-180.0f+x_offset, level.info->skyrotatevector2.X, level.info->skyrotatevector2.Z, level.info->skyrotatevector2.Y);
+        state.mModelMatrix.rotate(-180.0f+x_offset, ::level.info->skyrotatevector2.X, ::level.info->skyrotatevector2.Z, ::level.info->skyrotatevector2.Y);
 
 	if (sb->faces[5]) 
 	{
diff --git a/src/hwrenderer/scene/hw_walls.cpp b/src/hwrenderer/scene/hw_walls.cpp
index 0622553f75..70ca0f6335 100644
--- a/src/hwrenderer/scene/hw_walls.cpp
+++ b/src/hwrenderer/scene/hw_walls.cpp
@@ -483,10 +483,10 @@ void GLWall::PutWall(HWDrawInfo *di, bool translucent)
 //
 //==========================================================================
 
-void GLWall::PutPortal(HWDrawInfo *di, int ptype)
+void GLWall::PutPortal(HWDrawInfo *di, int ptype, int plane)
 {
 	auto pstate = screen->mPortalState;
-	HWPortal * portal;
+	HWPortal * portal = nullptr;
 
 	MakeVertices(di, false);
 	switch (ptype)
@@ -498,7 +498,7 @@ void GLWall::PutPortal(HWDrawInfo *di, int ptype)
 		portal = di->FindPortal(horizon);
 		if (!portal)
 		{
-			portal = new HWHorizonPortal(pstate, horizon, di->Viewpoint, di);
+			portal = new HWHorizonPortal(pstate, horizon, di->Viewpoint);
 			di->Portals.Push(portal);
 		}
 		portal->AddLine(this);
@@ -509,10 +509,10 @@ void GLWall::PutPortal(HWDrawInfo *di, int ptype)
 		if (!portal)
 		{
 			// either a regular skybox or an Eternity-style horizon
-			if (secportal->mType != PORTS_SKYVIEWPOINT) portal = new HWEEHorizonPortal(pstate, secportal, di);
+			if (secportal->mType != PORTS_SKYVIEWPOINT) portal = new HWEEHorizonPortal(pstate, secportal);
 			else
 			{
-				portal = new HWScenePortal(pstate, new HWSkyboxPortal(secportal));
+				portal = new HWSkyboxPortal(pstate, secportal);
 				di->Portals.Push(portal);
 			}
 		}
@@ -523,7 +523,7 @@ void GLWall::PutPortal(HWDrawInfo *di, int ptype)
 		portal = di->FindPortal(this->portal);
 		if (!portal)
 		{
-			portal = new HWScenePortal(pstate, new HWSectorStackPortal(this->portal));
+			portal = new HWSectorStackPortal(pstate, this->portal);
 			di->Portals.Push(portal);
 		}
 		portal->AddLine(this);
@@ -532,12 +532,11 @@ void GLWall::PutPortal(HWDrawInfo *di, int ptype)
 	case PORTALTYPE_PLANEMIRROR:
 		if (pstate->PlaneMirrorMode * planemirror->fC() <= 0)
 		{
-			//@sync-portal
 			planemirror = pstate->UniquePlaneMirrors.Get(planemirror);
 			portal = di->FindPortal(planemirror);
 			if (!portal)
 			{
-				portal = new HWScenePortal(pstate, new HWPlaneMirrorPortal(planemirror));
+				portal = new HWPlaneMirrorPortal(pstate, planemirror);
 				di->Portals.Push(portal);
 			}
 			portal->AddLine(this);
@@ -548,7 +547,7 @@ void GLWall::PutPortal(HWDrawInfo *di, int ptype)
 		portal = di->FindPortal(seg->linedef);
 		if (!portal)
 		{
-			portal = new HWScenePortal(pstate, new HWMirrorPortal(seg->linedef));
+			portal = new HWMirrorPortal(pstate, seg->linedef);
 			di->Portals.Push(portal);
 		}
 		portal->AddLine(this);
@@ -570,7 +569,7 @@ void GLWall::PutPortal(HWDrawInfo *di, int ptype)
 			{
 				di->ProcessActorsInPortal(otherside->getPortal()->mGroup, di->in_area);
 			}
-			portal = new HWScenePortal(pstate, new HWLineToLinePortal(lineportal));
+			portal = new HWLineToLinePortal(pstate, lineportal);
 			di->Portals.Push(portal);
 		}
 		portal->AddLine(this);
@@ -588,6 +587,11 @@ void GLWall::PutPortal(HWDrawInfo *di, int ptype)
 		break;
 	}
 	vertcount = 0;
+
+	if (plane != -1 && portal)
+	{
+		portal->planesused |= (1<<plane);
+	}
 }
 
 //==========================================================================
@@ -849,7 +853,7 @@ bool GLWall::DoHorizon(HWDrawInfo *di, seg_t * seg,sector_t * fs, vertex_t * v1,
 
 			if (di->isFullbrightScene()) hi.colormap.Clear();
 			horizon = &hi;
-			PutPortal(di, PORTALTYPE_HORIZON);
+			PutPortal(di, PORTALTYPE_HORIZON, -1);
 		}
 		ztop[1] = ztop[0] = zbottom[0];
 	} 
@@ -878,7 +882,7 @@ bool GLWall::DoHorizon(HWDrawInfo *di, seg_t * seg,sector_t * fs, vertex_t * v1,
 
 			if (di->isFullbrightScene()) hi.colormap.Clear();
 			horizon = &hi;
-			PutPortal(di, PORTALTYPE_HORIZON);
+			PutPortal(di, PORTALTYPE_HORIZON, -1);
 		}
 	}
 	return true;
@@ -1135,7 +1139,7 @@ void GLWall::DoTexture(HWDrawInfo *di, int _type,seg_t * seg, int peg,
 
 	if (seg->linedef->special == Line_Mirror && _type == RENDERWALL_M1S && gl_mirrors)
 	{
-		PutPortal(di, PORTALTYPE_MIRROR);
+		PutPortal(di, PORTALTYPE_MIRROR, -1);
 	}
 	else
 	{
@@ -1970,7 +1974,7 @@ void GLWall::Process(HWDrawInfo *di, seg_t *seg, sector_t * frontsector, sector_
 			ztop[1] = zceil[1];
 			zbottom[0] = zfloor[0];
 			zbottom[1] = zfloor[1];
-			PutPortal(di, PORTALTYPE_LINETOLINE);
+			PutPortal(di, PORTALTYPE_LINETOLINE, -1);
 		}
 		else if (seg->linedef->GetTransferredPortal())
 		{
@@ -2077,7 +2081,7 @@ void GLWall::Process(HWDrawInfo *di, seg_t *seg, sector_t * frontsector, sector_
 			ztop[1] = bch2;
 			zbottom[0] = bfh1;
 			zbottom[1] = bfh2;
-			PutPortal(di, PORTALTYPE_LINETOLINE);
+			PutPortal(di, PORTALTYPE_LINETOLINE, -1);
 		}
 		else if (backsector->e->XFloor.ffloors.Size() || frontsector->e->XFloor.ffloors.Size())
 		{
diff --git a/src/info.cpp b/src/info.cpp
index ffae037f74..87332fd2b2 100644
--- a/src/info.cpp
+++ b/src/info.cpp
@@ -118,6 +118,37 @@ void FState::SetAction(const char *name)
 	ActionFunc = FindVMFunction(RUNTIME_CLASS(AActor), name);
 }
 
+
+void FState::CheckCallerType(AActor *self, AActor *stateowner)
+{
+	auto CheckType = [=](AActor *check, PType *requiredType)
+	{
+		// This should really never happen. Any valid action function must have actor pointers here.
+		if (!requiredType->isObjectPointer())
+		{
+			ThrowAbortException(X_OTHER, "Bad function prototype in function call to %s", ActionFunc->PrintableName.GetChars());
+		}
+		auto cls = static_cast<PObjectPointer*>(requiredType)->PointedClass();
+		if (!check->IsKindOf(cls))
+		{
+			ThrowAbortException(X_OTHER, "Invalid class %s in function call to %s. %s expected", check->GetClass()->TypeName.GetChars(), ActionFunc->PrintableName.GetChars(), cls->TypeName.GetChars());
+		}
+	};
+	
+	if (ActionFunc->ImplicitArgs >= 1)
+	{
+		auto argtypes = ActionFunc->Proto->ArgumentTypes;
+		
+		CheckType(self, argtypes[0]);
+		
+		if (ActionFunc->ImplicitArgs >= 2)
+		{
+			CheckType(stateowner, argtypes[1]);
+		}
+	}
+}
+
+
 bool FState::CallAction(AActor *self, AActor *stateowner, FStateParamInfo *info, FState **stateret)
 {
 	if (ActionFunc != nullptr)
@@ -140,6 +171,8 @@ bool FState::CallAction(AActor *self, AActor *stateowner, FStateParamInfo *info,
 		}
 		try
 		{
+			CheckCallerType(self, stateowner);
+			
 			if (stateret == nullptr)
 			{
 				VMCall(ActionFunc, params, ActionFunc->ImplicitArgs, nullptr, 0);
diff --git a/src/info.h b/src/info.h
index 69912534fa..184313a0eb 100644
--- a/src/info.h
+++ b/src/info.h
@@ -175,10 +175,13 @@ public:
 	void ClearAction() { ActionFunc = NULL; }
 	void SetAction(const char *name);
 	bool CallAction(AActor *self, AActor *stateowner, FStateParamInfo *stateinfo, FState **stateret);
+    void CheckCallerType(AActor *self, AActor *stateowner);
+
 	static PClassActor *StaticFindStateOwner (const FState *state);
 	static PClassActor *StaticFindStateOwner (const FState *state, PClassActor *info);
 	static FString StaticGetStateName(const FState *state);
 	static FRandom pr_statetics;
+
 };
 
 struct FStateLabels;
diff --git a/src/namedef.h b/src/namedef.h
index 5744ef4869..184c58fd0b 100644
--- a/src/namedef.h
+++ b/src/namedef.h
@@ -896,6 +896,8 @@ xx(DamageFunction)
 xx(Length)
 xx(Unit)
 xx(Size)
+xx(Push)
+xx(Insert)
 xx(Copy)
 xx(Move)
 xx(Voidptr)
diff --git a/src/p_actionfunctions.cpp b/src/p_actionfunctions.cpp
index 60771a469c..6e6e165008 100644
--- a/src/p_actionfunctions.cpp
+++ b/src/p_actionfunctions.cpp
@@ -169,6 +169,7 @@ bool AStateProvider::CallStateChain (AActor *actor, FState *state)
 			}
 			try
 			{
+                state->CheckCallerType(actor, this);
 				VMCall(state->ActionFunc, params, state->ActionFunc->ImplicitArgs, wantret, numret);
 			}
 			catch (CVMAbortException &err)
diff --git a/src/portal.h b/src/portal.h
index 01b17fc8be..daeb784f60 100644
--- a/src/portal.h
+++ b/src/portal.h
@@ -249,7 +249,6 @@ struct FSectorPortal
 //
 //============================================================================
 
-struct GLSectorStackPortal;
 struct FSectorPortalGroup
 {
 	DVector2 mDisplacement;
@@ -286,4 +285,4 @@ DVector2 P_GetOffsetPosition(double x, double y, double dx, double dy);
 void InitPortalGroups();
 
 
-#endif
\ No newline at end of file
+#endif
diff --git a/src/r_data/r_sections.cpp b/src/r_data/r_sections.cpp
index 74b89f9a59..8f10f2fb33 100644
--- a/src/r_data/r_sections.cpp
+++ b/src/r_data/r_sections.cpp
@@ -495,9 +495,9 @@ public:
 			auto &section = sections[i];
 			auto &work = triangles[i];
 
-			BoundingRect bounds = { 1e32, 1e32, -1e32, -1e32 };
-			BoundingRect loopBounds = { 1e32, 1e32, -1e32, -1e32 };
-			BoundingRect outermostBounds = { 1e32, 1e32, -1e32, -1e32 };
+			BoundingRect bounds(false);
+			BoundingRect loopBounds(false);
+			BoundingRect outermostBounds(false);
 			unsigned outermoststart = ~0u;
 			unsigned loopstart = 0;
 			bool ispolyorg = false;
@@ -519,7 +519,7 @@ public:
 						outermoststart = loopstart;
 						loopstart = i + 1;
 					}
-					loopBounds = { 1e32, 1e32, -1e32, -1e32 };
+					loopBounds.setEmpty();
 				}
 			}
 			work.boundingLoopStart = outermoststart;
@@ -716,7 +716,7 @@ public:
 			dest.subsectors.Set(&output.allSubsectors[numsubsectors], group.subsectors.Size());
 			dest.vertexindex = -1;
 			dest.vertexcount = 0;
-			dest.bounds = {1e32, 1e32, -1e32, -1e32};
+			dest.bounds.setEmpty();
 			numsegments += group.segments.Size();
 
 			if (output.firstSectionForSectorPtr[dest.sector->Index()] == -1)
diff --git a/src/r_data/r_sections.h b/src/r_data/r_sections.h
index 96ab3c2500..35f61cb7cd 100644
--- a/src/r_data/r_sections.h
+++ b/src/r_data/r_sections.h
@@ -25,12 +25,35 @@ struct BoundingRect
 {
 	double left, top, right, bottom;
 
-	bool contains(const BoundingRect & other)
+	BoundingRect() = default;
+	BoundingRect(bool)
+	{
+		setEmpty();
+	}
+
+	void setEmpty()
+	{
+		left = top = 1e38;
+		bottom = right = -1e38;
+	}
+
+	bool contains(const BoundingRect & other) const
 	{
 		return left <= other.left && top <= other.top && right >= other.right && bottom >= other.bottom;
 	}
 
-	bool intersects(const BoundingRect & other)
+	bool contains(double x, double y) const
+	{
+		return left <= x && top <= y && right >= x && bottom >= y;
+	}
+
+	template <class T>
+	bool contains(const T &vec) const
+	{
+		return left <= vec.X && top <= vec.Y && right >= vec.X && bottom >= vec.Y;
+	}
+
+	bool intersects(const BoundingRect & other) const
 	{
 		return !(other.left > right ||
 			other.right < left ||
@@ -46,7 +69,7 @@ struct BoundingRect
 		if (other.bottom > bottom) bottom = other.bottom;
 	}
 
-	double distanceTo(const BoundingRect &other)
+	double distanceTo(const BoundingRect &other) const
 	{
 		if (intersects(other)) return 0;
 		return std::max(std::min(fabs(left - other.right), fabs(right - other.left)),
@@ -61,10 +84,11 @@ struct BoundingRect
 		if (y > bottom) bottom = y;
 	}
 
-	bool operator == (const BoundingRect &other)
+	bool operator == (const BoundingRect &other) const
 	{
 		return left == other.left && top == other.top && right == other.right && bottom == other.bottom;
 	}
+
 };
 
 
diff --git a/src/scripting/backend/codegen.cpp b/src/scripting/backend/codegen.cpp
index b6059a49c6..79b48953a4 100644
--- a/src/scripting/backend/codegen.cpp
+++ b/src/scripting/backend/codegen.cpp
@@ -8240,7 +8240,9 @@ FxExpression *FxMemberFunctionCall::Resolve(FCompileContext& ctx)
 		{
 			auto elementType = static_cast<PDynArray*>(Self->ValueType)->ElementType;
 			Self->ValueType = static_cast<PDynArray*>(Self->ValueType)->BackingType;
+			bool isDynArrayObj = elementType->isObjectPointer();
 			// this requires some added type checks for the passed types.
+			int idx = 0;
 			for (auto &a : ArgList)
 			{
 				a = a->Resolve(ctx);
@@ -8249,6 +8251,16 @@ FxExpression *FxMemberFunctionCall::Resolve(FCompileContext& ctx)
 					delete this;
 					return nullptr;
 				}
+				if (isDynArrayObj && ((MethodName == NAME_Push && idx == 0) || (MethodName == NAME_Insert && idx == 1)))
+				{
+					// The DynArray_Obj declaration in dynarrays.txt doesn't support generics yet. Check the type here as if it did.
+					if (!static_cast<PObjectPointer*>(elementType)->PointedClass()->IsAncestorOf(static_cast<PObjectPointer*>(a->ValueType)->PointedClass()))
+					{
+						ScriptPosition.Message(MSG_ERROR, "Type mismatch in function argument");
+						delete this;
+						return nullptr;
+					}
+				}
 				if (a->IsDynamicArray())
 				{
 					// Copy and Move must turn their parameter into a pointer to the backing struct type.
@@ -8288,6 +8300,7 @@ FxExpression *FxMemberFunctionCall::Resolve(FCompileContext& ctx)
 						return nullptr;
 					}
 				}
+				idx++;
 			}
 		}
 	}