diff --git a/src/swrenderer/scene/r_viewport.cpp b/src/swrenderer/scene/r_viewport.cpp
index 1fc4494a80..24413b3c55 100644
--- a/src/swrenderer/scene/r_viewport.cpp
+++ b/src/swrenderer/scene/r_viewport.cpp
@@ -148,10 +148,6 @@ namespace swrenderer
 		FocalLengthX = CenterX / FocalTangent;
 		FocalLengthY = FocalLengthX * YaspectMul;
 
-		// This is 1/FocalTangent before the widescreen extension of FOV.
-		viewingrangerecip = FLOAT2FIXED(1. / tan(FieldOfView.Radians() / 2));
-
-
 		// Now generate xtoviewangle for sky texture mapping.
 		// [RH] Do not generate viewangletox, because texture mapping is no
 		// longer done with trig, so it's not needed.
@@ -167,4 +163,46 @@ namespace swrenderer
 			xtoviewangle[i] = 0 - xtoviewangle[viewwidth - i - 1];
 		}
 	}
+
+	DVector2 RenderViewport::PointWorldToView(const DVector2 &worldPos) const
+	{
+		double translatedX = worldPos.X - ViewPos.X;
+		double translatedY = worldPos.Y - ViewPos.Y;
+		return {
+			translatedX * ViewSin - translatedY * ViewCos,
+			translatedX * ViewTanCos + translatedY * ViewTanSin
+		};
+	}
+
+	DVector3 RenderViewport::PointWorldToView(const DVector3 &worldPos) const
+	{
+		double translatedX = worldPos.X - ViewPos.X;
+		double translatedY = worldPos.Y - ViewPos.Y;
+		double translatedZ = worldPos.Z - ViewPos.Z;
+		return {
+			translatedX * ViewSin - translatedY * ViewCos,
+			translatedZ,
+			translatedX * ViewTanCos + translatedY * ViewTanSin
+		};
+	}
+
+	DVector3 RenderViewport::PointWorldToScreen(const DVector3 &worldPos) const
+	{
+		return PointViewToScreen(PointWorldToView(worldPos));
+	}
+
+	DVector3 RenderViewport::PointViewToScreen(const DVector3 &viewPos) const
+	{
+		double screenX = CenterX + viewPos.X / viewPos.Z * CenterX;
+		double screenY = CenterY - viewPos.Y / viewPos.Z * InvZtoScale;
+		return { screenX, screenY, viewPos.Z };
+	}
+
+	DVector2 RenderViewport::ScaleViewToScreen(const DVector2 &scale, double viewZ, bool pixelstretch) const
+	{
+		double screenScaleX = scale.X / viewZ * CenterX;
+		double screenScaleY = scale.Y / viewZ * InvZtoScale;
+		if (!pixelstretch) screenScaleY /= YaspectMul;
+		return { screenScaleX, screenScaleY };
+	}
 }
diff --git a/src/swrenderer/scene/r_viewport.h b/src/swrenderer/scene/r_viewport.h
index ea5436980f..d89dbec6ec 100644
--- a/src/swrenderer/scene/r_viewport.h
+++ b/src/swrenderer/scene/r_viewport.h
@@ -27,7 +27,7 @@ namespace swrenderer
 		void SetupFreelook();
 		
 		DCanvas *RenderTarget = nullptr;
-		fixed_t viewingrangerecip = 0;
+
 		double FocalLengthX = 0.0;
 		double FocalLengthY = 0.0;
 		double InvZtoScale = 0.0;
@@ -48,6 +48,13 @@ namespace swrenderer
 
 		bool RenderingToCanvas() const { return RenderTarget != screen; }
 
+		DVector3 PointWorldToView(const DVector3 &worldPos) const;
+		DVector3 PointWorldToScreen(const DVector3 &worldPos) const;
+		DVector3 PointViewToScreen(const DVector3 &viewPos) const;
+
+		DVector2 PointWorldToView(const DVector2 &worldPos) const;
+		DVector2 ScaleViewToScreen(const DVector2 &scale, double viewZ, bool pixelstretch = true) const;
+
 	private:
 		void InitTextureMapping();
 		void SetupBuffer();
diff --git a/src/swrenderer/things/r_voxel.cpp b/src/swrenderer/things/r_voxel.cpp
index 6da831163a..7f30257bb9 100644
--- a/src/swrenderer/things/r_voxel.cpp
+++ b/src/swrenderer/things/r_voxel.cpp
@@ -318,35 +318,18 @@ namespace swrenderer
 	{
 		auto viewport = RenderViewport::Instance();
 		
-		double viewX, viewY, viewZ;
-		if (viewspace)
-		{
-			viewX = origin.X;
-			viewY = origin.Y;
-			viewZ = origin.Z;
-		}
-		else // world space
-		{
-			double translatedX = origin.X - ViewPos.X;
-			double translatedY = origin.Y - ViewPos.Y;
-			double translatedZ = origin.Z - ViewPos.Z;
-			viewX = translatedX * ViewSin - translatedY * ViewCos;
-			viewY = translatedZ;
-			viewZ = translatedX * ViewTanCos + translatedY * ViewTanSin;
-		}
+		DVector3 viewPos = viewport->PointWorldToView(origin);
 
-		if (viewZ < 0.01f)
+		if (viewPos.Z < 0.01f)
 			return;
 
-		double screenX = viewport->CenterX + viewX / viewZ * viewport->CenterX;
-		double screenY = viewport->CenterY - viewY / viewZ * viewport->InvZtoScale;
-		double screenExtentX = extentX / viewZ * viewport->CenterX;
-		double screenExtentY = pixelstretch ? screenExtentX * viewport->YaspectMul : screenExtentX;
+		DVector3 screenPos = viewport->PointViewToScreen(viewPos);
+		DVector2 screenExtent = viewport->ScaleViewToScreen({ extentX, extentY }, viewPos.Z, pixelstretch);
 
-		int x1 = MAX((int)(screenX - screenExtentX), 0);
-		int x2 = MIN((int)(screenX + screenExtentX + 0.5f), viewwidth - 1);
-		int y1 = MAX((int)(screenY - screenExtentY), 0);
-		int y2 = MIN((int)(screenY + screenExtentY + 0.5f), viewheight - 1);
+		int x1 = MAX((int)(screenPos.X - screenExtent.X), 0);
+		int x2 = MIN((int)(screenPos.X + screenExtent.X + 0.5f), viewwidth - 1);
+		int y1 = MAX((int)(screenPos.Y - screenExtent.Y), 0);
+		int y2 = MIN((int)(screenPos.Y + screenExtent.Y + 0.5f), viewheight - 1);
 
 		int pixelsize = viewport->RenderTarget->IsBgra() ? 4 : 1;