diff --git a/src/r_compiler/fixedfunction/drawtrianglecodegen.cpp b/src/r_compiler/fixedfunction/drawtrianglecodegen.cpp
index 6f9af51fc..8bf4779e2 100644
--- a/src/r_compiler/fixedfunction/drawtrianglecodegen.cpp
+++ b/src/r_compiler/fixedfunction/drawtrianglecodegen.cpp
@@ -78,10 +78,10 @@ void DrawTriangleCodegen::Setup(TriDrawVariant variant, bool truecolor)
 	FDY31 = DY31 << 4;
 
 	// Bounding rectangle
-	minx = SSAInt::MAX((SSAInt::MIN(SSAInt::MIN(X1, X2), X3) + 0xF) >> 4, clipleft);
-	maxx = SSAInt::MIN((SSAInt::MAX(SSAInt::MAX(X1, X2), X3) + 0xF) >> 4, clipright - 1);
-	miny = SSAInt::MAX((SSAInt::MIN(SSAInt::MIN(Y1, Y2), Y3) + 0xF) >> 4, cliptop);
-	maxy = SSAInt::MIN((SSAInt::MAX(SSAInt::MAX(Y1, Y2), Y3) + 0xF) >> 4, clipbottom - 1);
+	minx = SSAInt::MAX((SSAInt::MIN(SSAInt::MIN(X1, X2), X3) + 0xF).ashr(4), clipleft);
+	maxx = SSAInt::MIN((SSAInt::MAX(SSAInt::MAX(X1, X2), X3) + 0xF).ashr(4), clipright - 1);
+	miny = SSAInt::MAX((SSAInt::MIN(SSAInt::MIN(Y1, Y2), Y3) + 0xF).ashr(4), cliptop);
+	maxy = SSAInt::MIN((SSAInt::MAX(SSAInt::MAX(Y1, Y2), Y3) + 0xF).ashr(4), clipbottom - 1);
 
 	SSAIfBlock if0;
 	if0.if_block(minx >= maxx || miny >= maxy);
@@ -221,7 +221,7 @@ void DrawTriangleCodegen::LoopBlockX(TriDrawVariant variant, bool truecolor)
 		branch.if_block(!(a == SSAInt(0) || b == SSAInt(0) || c == SSAInt(0)));
 
 		// Check if block needs clipping
-		SSABool clipneeded = clipleft > x || clipright < (x + q) || cliptop > y || clipbottom < (y + q);
+		SSABool clipneeded = x < clipleft || (x + q) > clipright || y < cliptop || (y + q) > clipbottom;
 
 		// Calculate varying variables for affine block
 		SSAFloat offx0 = SSAFloat(x - minx);
@@ -401,7 +401,7 @@ void DrawTriangleCodegen::LoopPartialBlock(TriDrawVariant variant, bool truecolo
 			varying[i] = stack_varying[i].load();
 		loopx.loop_block(ix < SSAInt(q), q);
 		{
-			SSABool visible = (ix + x >= clipleft) && (ix + x < clipright) && (cliptop <= y + iy) && (clipbottom > y + iy);
+			SSABool visible = (ix + x >= clipleft) && (ix + x < clipright) && (iy + y >= cliptop) && (iy + y < clipbottom);
 			SSABool covered = CX1 > SSAInt(0) && CX2 > SSAInt(0) && CX3 > SSAInt(0) && visible;
 
 			if (variant == TriDrawVariant::DrawSubsector || variant == TriDrawVariant::DrawShadedSubsector || variant == TriDrawVariant::FillSubsector)
@@ -589,9 +589,9 @@ void DrawTriangleCodegen::LoadArgs(TriDrawVariant variant, bool truecolor, SSAVa
 	v1 = LoadTriVertex(args[0][2].load(true));
 	v2 = LoadTriVertex(args[0][3].load(true));
 	v3 = LoadTriVertex(args[0][4].load(true));
-	clipleft = args[0][5].load(true);
+	clipleft = SSAInt(0);// args[0][5].load(true);
 	clipright = args[0][6].load(true);
-	cliptop = args[0][7].load(true);
+	cliptop = SSAInt(0);// args[0][7].load(true);
 	clipbottom = args[0][8].load(true);
 	texturePixels = args[0][9].load(true);
 	textureWidth = args[0][10].load(true);
diff --git a/src/r_poly.cpp b/src/r_poly.cpp
index ade89571e..7a06a471e 100644
--- a/src/r_poly.cpp
+++ b/src/r_poly.cpp
@@ -62,8 +62,8 @@ void RenderPolyScene::ClearBuffers()
 	SectorSpriteRanges.resize(numsectors);
 	SortedSprites.clear();
 	TranslucentObjects.clear();
-	PolyStencilBuffer::Instance()->Clear(viewwidth, viewheight, 0);
-	PolySubsectorGBuffer::Instance()->Resize(dc_pitch, viewheight);
+	PolyStencilBuffer::Instance()->Clear(screen->GetWidth(), screen->GetHeight(), 0);
+	PolySubsectorGBuffer::Instance()->Resize(screen->GetPitch(), screen->GetHeight());
 	NextSubsectorDepth = 0;
 }
 
@@ -79,14 +79,12 @@ void RenderPolyScene::SetupPerspectiveMatrix()
 
 	int height;
 	if (screenblocks >= 10)
-	{
 		height = SCREENHEIGHT;
-	}
 	else
-	{
 		height = (screenblocks*SCREENHEIGHT / 10) & ~7;
-	}
-	viewheight = height; // So viewheight was calculated incorrectly. That's just.. wonderful.
+
+	int bottom = SCREENHEIGHT - (height + viewwindowy - ((height - viewheight) / 2));
+	PolyTriangleDrawer::set_viewport(viewwindowx, SCREENHEIGHT - bottom - height, viewwidth, height, screen);
 
 	// Code provided courtesy of Graf Zahl. Now we just have to plug it into the viewmatrix code...
 	// We have to scale the pitch to account for the pixel stretching, because the playsim doesn't know about this and treats it as 1:1.
@@ -105,6 +103,7 @@ void RenderPolyScene::SetupPerspectiveMatrix()
 		TriMatrix::scale(1.0f, glset.pixelstretch, 1.0f) *
 		TriMatrix::swapYZ() *
 		TriMatrix::translate((float)-ViewPos.X, (float)-ViewPos.Y, (float)-ViewPos.Z);
+
 	WorldToClip = TriMatrix::perspective(fovy, ratio, 5.0f, 65535.0f) * worldToView;
 }
 
diff --git a/src/r_poly_decal.cpp b/src/r_poly_decal.cpp
index 011ce83e4..0c6c427a8 100644
--- a/src/r_poly_decal.cpp
+++ b/src/r_poly_decal.cpp
@@ -148,10 +148,6 @@ void RenderPolyDecal::Render(const TriMatrix &worldToClip, DBaseDecal *decal, co
 	args.vcount = 4;
 	args.mode = TriangleDrawMode::Fan;
 	args.ccw = true;
-	args.clipleft = 0;
-	args.cliptop = 0;
-	args.clipright = viewwidth;
-	args.clipbottom = viewheight;
 	args.stenciltestvalue = 0;
 	args.stencilwritevalue = 1;
 	args.SetTexture(tex);
diff --git a/src/r_poly_particle.cpp b/src/r_poly_particle.cpp
index f0b221988..be8030071 100644
--- a/src/r_poly_particle.cpp
+++ b/src/r_poly_particle.cpp
@@ -92,10 +92,6 @@ void RenderPolyParticle::Render(const TriMatrix &worldToClip, particle_t *partic
 	args.vcount = 4;
 	args.mode = TriangleDrawMode::Fan;
 	args.ccw = true;
-	args.clipleft = 0;
-	args.cliptop = 0;
-	args.clipright = viewwidth;
-	args.clipbottom = viewheight;
 	args.stenciltestvalue = 0;
 	args.stencilwritevalue = 1;
 	args.solidcolor = (alpha << 24) | (particle->color & 0xffffff);
diff --git a/src/r_poly_plane.cpp b/src/r_poly_plane.cpp
index 5b0e912a8..9a425598b 100644
--- a/src/r_poly_plane.cpp
+++ b/src/r_poly_plane.cpp
@@ -137,10 +137,6 @@ void RenderPolyPlane::Render3DFloor(const TriMatrix &worldToClip, subsector_t *s
 	args.vcount = sub->numlines;
 	args.mode = TriangleDrawMode::Fan;
 	args.ccw = true;
-	args.clipleft = 0;
-	args.cliptop = 0;
-	args.clipright = viewwidth;
-	args.clipbottom = viewheight;
 	args.stenciltestvalue = 0;
 	args.stencilwritevalue = 1;
 	args.SetTexture(tex);
@@ -233,10 +229,6 @@ void RenderPolyPlane::Render(const TriMatrix &worldToClip, subsector_t *sub, uin
 	args.vcount = sub->numlines;
 	args.mode = TriangleDrawMode::Fan;
 	args.ccw = ccw;
-	args.clipleft = 0;
-	args.cliptop = 0;
-	args.clipright = viewwidth;
-	args.clipbottom = viewheight;
 	args.stenciltestvalue = 0;
 	args.stencilwritevalue = 1;
 
diff --git a/src/r_poly_sky.cpp b/src/r_poly_sky.cpp
index 03a4bfdb2..fc6963dbb 100644
--- a/src/r_poly_sky.cpp
+++ b/src/r_poly_sky.cpp
@@ -59,10 +59,6 @@ void PolySkyDome::Render(const TriMatrix &worldToClip)
 
 	PolyDrawArgs args;
 	args.uniforms = uniforms;
-	args.clipleft = 0;
-	args.cliptop = 0;
-	args.clipright = viewwidth;
-	args.clipbottom = viewheight;
 	args.stenciltestvalue = 255;
 	args.stencilwritevalue = 1;
 	args.SetTexture(frontskytex);
diff --git a/src/r_poly_sprite.cpp b/src/r_poly_sprite.cpp
index 1701b24ef..e1c6fcc14 100644
--- a/src/r_poly_sprite.cpp
+++ b/src/r_poly_sprite.cpp
@@ -133,10 +133,6 @@ void RenderPolySprite::Render(const TriMatrix &worldToClip, AActor *thing, subse
 	args.vcount = 4;
 	args.mode = TriangleDrawMode::Fan;
 	args.ccw = true;
-	args.clipleft = 0;
-	args.cliptop = 0;
-	args.clipright = viewwidth;
-	args.clipbottom = viewheight;
 	args.stenciltestvalue = 0;
 	args.stencilwritevalue = 1;
 	args.SetTexture(tex);
diff --git a/src/r_poly_triangle.cpp b/src/r_poly_triangle.cpp
index 64611376b..d661fe0d7 100644
--- a/src/r_poly_triangle.cpp
+++ b/src/r_poly_triangle.cpp
@@ -40,9 +40,41 @@
 #include <immintrin.h>
 #endif
 
+int PolyTriangleDrawer::viewport_x;
+int PolyTriangleDrawer::viewport_y;
+int PolyTriangleDrawer::viewport_width;
+int PolyTriangleDrawer::viewport_height;
+int PolyTriangleDrawer::dest_pitch;
+int PolyTriangleDrawer::dest_width;
+int PolyTriangleDrawer::dest_height;
+uint8_t *PolyTriangleDrawer::dest;
+bool PolyTriangleDrawer::dest_bgra;
+
+void PolyTriangleDrawer::set_viewport(int x, int y, int width, int height, DCanvas *canvas)
+{
+	dest = (uint8_t*)canvas->GetBuffer();
+	dest_width = canvas->GetWidth();
+	dest_height = canvas->GetHeight();
+	dest_pitch = canvas->GetPitch();
+	dest_bgra = canvas->IsBgra();
+
+	int offsetx = clamp(x, 0, dest_width);
+	int offsety = clamp(y, 0, dest_height);
+	int pixelsize = dest_bgra ? 4 : 1;
+
+	viewport_x = x - offsetx;
+	viewport_y = y - offsety;
+	viewport_width = width;
+	viewport_height = height;
+
+	dest += (offsetx + offsety * dest_pitch) * pixelsize;
+	dest_width = clamp(viewport_x + viewport_width, 0, dest_width - offsetx);
+	dest_height = clamp(viewport_y + viewport_height, 0, dest_height - offsety);
+}
+
 void PolyTriangleDrawer::draw(const PolyDrawArgs &args, TriDrawVariant variant)
 {
-	if (r_swtruecolor)
+	if (dest_bgra)
 		DrawerCommandQueue::QueueCommand<DrawPolyTrianglesCommand>(args, variant);
 	else
 		draw_arrays(args, variant, nullptr);
@@ -59,33 +91,33 @@ void PolyTriangleDrawer::draw_arrays(const PolyDrawArgs &drawargs, TriDrawVarian
 	switch (variant)
 	{
 	default:
-	case TriDrawVariant::Draw: drawfunc = r_swtruecolor ? llvm->TriDraw32: llvm->TriDraw8; break;
-	case TriDrawVariant::Fill: drawfunc = r_swtruecolor ? llvm->TriFill32 : llvm->TriFill8; break;
-	case TriDrawVariant::DrawSubsector: drawfunc = r_swtruecolor ? llvm->TriDrawSubsector32 : llvm->TriDrawSubsector8; break;
-	case TriDrawVariant::DrawShadedSubsector: drawfunc = r_swtruecolor ? llvm->TriDrawShadedSubsector32 : llvm->TriDrawShadedSubsector8; break;
-	case TriDrawVariant::FillSubsector: drawfunc = r_swtruecolor ? llvm->TriFillSubsector32 : llvm->TriFillSubsector8; break;
+	case TriDrawVariant::Draw: drawfunc = dest_bgra ? llvm->TriDraw32: llvm->TriDraw8; break;
+	case TriDrawVariant::Fill: drawfunc = dest_bgra ? llvm->TriFill32 : llvm->TriFill8; break;
+	case TriDrawVariant::DrawSubsector: drawfunc = dest_bgra ? llvm->TriDrawSubsector32 : llvm->TriDrawSubsector8; break;
+	case TriDrawVariant::DrawShadedSubsector: drawfunc = dest_bgra ? llvm->TriDrawShadedSubsector32 : llvm->TriDrawShadedSubsector8; break;
+	case TriDrawVariant::FillSubsector: drawfunc = dest_bgra ? llvm->TriFillSubsector32 : llvm->TriFillSubsector8; break;
 	case TriDrawVariant::Stencil: drawfunc = llvm->TriStencil; break;
 	}
 #else
 	switch (variant)
 	{
 	default:
-	case TriDrawVariant::Draw: drawfunc = r_swtruecolor ? ScreenPolyTriangleDrawer::draw32 : ScreenPolyTriangleDrawer::draw; break;
+	case TriDrawVariant::Draw: drawfunc = dest_bgra ? ScreenPolyTriangleDrawer::draw32 : ScreenPolyTriangleDrawer::draw; break;
 	case TriDrawVariant::FillSubsector:
-	case TriDrawVariant::Fill: drawfunc = r_swtruecolor ? ScreenPolyTriangleDrawer::fill32 : ScreenPolyTriangleDrawer::fill; break;
+	case TriDrawVariant::Fill: drawfunc = dest_bgra ? ScreenPolyTriangleDrawer::fill32 : ScreenPolyTriangleDrawer::fill; break;
 	case TriDrawVariant::DrawShadedSubsector:
-	case TriDrawVariant::DrawSubsector: drawfunc = r_swtruecolor ? ScreenPolyTriangleDrawer::drawsubsector32 : llvm->TriDrawSubsector8; break;
+	case TriDrawVariant::DrawSubsector: drawfunc = dest_bgra ? ScreenPolyTriangleDrawer::drawsubsector32 : llvm->TriDrawSubsector8; break;
 	case TriDrawVariant::Stencil: drawfunc = ScreenPolyTriangleDrawer::stencil; break;
 	}
 #endif
 
 	TriDrawTriangleArgs args;
-	args.dest = dc_destorg;
-	args.pitch = dc_pitch;
-	args.clipleft = drawargs.clipleft;
-	args.clipright = drawargs.clipright;
-	args.cliptop = drawargs.cliptop;
-	args.clipbottom = drawargs.clipbottom;
+	args.dest = dest;
+	args.pitch = dest_pitch;
+	args.clipleft = 0;
+	args.clipright = dest_width;
+	args.cliptop = 0;
+	args.clipbottom = dest_height;
 	args.texturePixels = drawargs.texturePixels;
 	args.textureWidth = drawargs.textureWidth;
 	args.textureHeight = drawargs.textureHeight;
@@ -163,8 +195,8 @@ void PolyTriangleDrawer::draw_shaded_triangle(const TriVertex *vert, bool ccw, T
 		v.z *= v.w;
 
 		// Apply viewport scale to get screen coordinates:
-		v.x = viewwidth * (1.0f + v.x) * 0.5f;
-		v.y = viewheight * (1.0f - v.y) * 0.5f;
+		v.x = viewport_x + viewport_width * (1.0f + v.x) * 0.5f;
+		v.y = viewport_y + viewport_height * (1.0f - v.y) * 0.5f;
 	}
 
 	// Draw screen triangles
diff --git a/src/r_poly_triangle.h b/src/r_poly_triangle.h
index f3f63f8f1..8f2fcf3d0 100644
--- a/src/r_poly_triangle.h
+++ b/src/r_poly_triangle.h
@@ -36,10 +36,6 @@ public:
 	int vcount = 0;
 	TriangleDrawMode mode = TriangleDrawMode::Normal;
 	bool ccw = false;
-	int clipleft = 0;
-	int clipright = 0;
-	int cliptop = 0;
-	int clipbottom = 0;
 	const uint8_t *texturePixels = nullptr;
 	int textureWidth = 0;
 	int textureHeight = 0;
@@ -61,6 +57,7 @@ public:
 class PolyTriangleDrawer
 {
 public:
+	static void set_viewport(int x, int y, int width, int height, DCanvas *canvas);
 	static void draw(const PolyDrawArgs &args, TriDrawVariant variant);
 
 private:
@@ -70,6 +67,10 @@ private:
 	static bool cullhalfspace(float clipdistance1, float clipdistance2, float &t1, float &t2);
 	static void clipedge(const TriVertex *verts, TriVertex *clippedvert, int &numclipvert);
 
+	static int viewport_x, viewport_y, viewport_width, viewport_height, dest_pitch, dest_width, dest_height;
+	static bool dest_bgra;
+	static uint8_t *dest;
+
 	enum { max_additional_vertices = 16 };
 
 	friend class DrawPolyTrianglesCommand;
diff --git a/src/r_poly_wall.cpp b/src/r_poly_wall.cpp
index 2ed225cf2..1f1908ab4 100644
--- a/src/r_poly_wall.cpp
+++ b/src/r_poly_wall.cpp
@@ -187,10 +187,6 @@ void RenderPolyWall::Render(const TriMatrix &worldToClip)
 	args.vcount = 4;
 	args.mode = TriangleDrawMode::Fan;
 	args.ccw = true;
-	args.clipleft = 0;
-	args.cliptop = 0;
-	args.clipright = viewwidth;
-	args.clipbottom = viewheight;
 	args.stenciltestvalue = 0;
 	args.stencilwritevalue = 1;
 	args.SetTexture(tex);
diff --git a/src/r_poly_wallsprite.cpp b/src/r_poly_wallsprite.cpp
index c6b3a6569..e2d1a9e86 100644
--- a/src/r_poly_wallsprite.cpp
+++ b/src/r_poly_wallsprite.cpp
@@ -118,10 +118,6 @@ void RenderPolyWallSprite::Render(const TriMatrix &worldToClip, AActor *thing, s
 	args.vcount = 4;
 	args.mode = TriangleDrawMode::Fan;
 	args.ccw = true;
-	args.clipleft = 0;
-	args.cliptop = 0;
-	args.clipright = viewwidth;
-	args.clipbottom = viewheight;
 	args.stenciltestvalue = 0;
 	args.stencilwritevalue = 1;
 	args.SetTexture(tex);