diff --git a/src/rendering/swrenderer/drawers/r_draw_pal.cpp b/src/rendering/swrenderer/drawers/r_draw_pal.cpp
index 3aca6797a28..9f1b197ef1a 100644
--- a/src/rendering/swrenderer/drawers/r_draw_pal.cpp
+++ b/src/rendering/swrenderer/drawers/r_draw_pal.cpp
@@ -1823,7 +1823,7 @@ namespace swrenderer
 		// Screen space to view space
 		viewpos_z = 1.0f / viewpos_z;
 		viewpos_x *= viewpos_z;
-		viewpos_y *= viewpos_y;
+		viewpos_y *= viewpos_z;
 
 		for (int i = 0; i < num_lights; i++)
 		{
@@ -1843,8 +1843,15 @@ namespace swrenderer
 #else
 			float rcp_dist = _mm_cvtss_f32(_mm_rsqrt_ss(_mm_load_ss(&dist2)));
 #endif
+			Lx *= rcp_dist;
+			Ly *= rcp_dist;
+			Lz *= rcp_dist;
 			float dist = dist2 * rcp_dist;
-			float distance_attenuation = (256.0f - min(dist * lights[i].radius, 256.0f));
+			float radius = lights[i].radius;
+			bool simpleType = radius < 0.0f;
+			if (simpleType)
+				radius = -radius;
+			float distance_attenuation = (256.0f - min(dist * radius, 256.0f));
 
 			// The simple light type
 			float simple_attenuation = distance_attenuation;
@@ -1852,8 +1859,8 @@ namespace swrenderer
 			// The point light type
 			// diffuse = dot(N,L) * attenuation
 			float dotNL = max(nx * Lx + ny * Ly + nz * Lz, 0.0f);
-			float point_attenuation = dotNL * rcp_dist * distance_attenuation;
-			uint32_t attenuation = (uint32_t)(lights[i].z == 0.0f ? simple_attenuation : point_attenuation);
+			float point_attenuation = dotNL * distance_attenuation;
+			uint32_t attenuation = (uint32_t)(simpleType ? simple_attenuation : point_attenuation);
 
 			lit_r += (light_color_r * attenuation) >> 8;
 			lit_g += (light_color_g * attenuation) >> 8;
@@ -2855,7 +2862,7 @@ namespace swrenderer
 			auto num_lights = args.dc_num_lights;
 			auto normal = args.dc_normal;
 			auto viewpos = args.dc_viewpos;
-			auto dc_viewpos_step = args.dc_viewpos_step;
+			auto viewpos_step = args.dc_viewpos_step;
 			while (width >= SPANSIZE)
 			{
 				iz += izstep;
@@ -2878,7 +2885,7 @@ namespace swrenderer
 					x1++;
 					u += stepu;
 					v += stepv;
-					viewpos += dc_viewpos_step;
+					viewpos += viewpos_step;
 				}
 				startu = endu;
 				startv = endv;
@@ -2918,7 +2925,7 @@ namespace swrenderer
 						x1++;
 						u += stepu;
 						v += stepv;
-						viewpos += dc_viewpos_step;
+						viewpos += viewpos_step;
 					}
 				}
 			}
diff --git a/src/rendering/swrenderer/plane/r_slopeplane.cpp b/src/rendering/swrenderer/plane/r_slopeplane.cpp
index d35901a5497..808a1a0b732 100644
--- a/src/rendering/swrenderer/plane/r_slopeplane.cpp
+++ b/src/rendering/swrenderer/plane/r_slopeplane.cpp
@@ -88,11 +88,14 @@ namespace swrenderer
 
 		auto viewport = Thread->Viewport.get();
 
-		DVector3 worldNormal = pl->height.Normal();
-		planeNormal.X = worldNormal.X * viewport->viewpoint.Sin - worldNormal.Y * viewport->viewpoint.Cos;
-		planeNormal.Y = worldNormal.X * viewport->viewpoint.Cos + worldNormal.Y * viewport->viewpoint.Sin;
-		planeNormal.Z = worldNormal.Z;
-		planeD = -planeNormal.Z * (pl->height.ZatPoint(viewport->viewpoint.Pos.X, viewport->viewpoint.Pos.Y) - viewport->viewpoint.Pos.Z);
+		// Stupid way of doing it, but at least it works
+		DVector3 worldP0(viewport->viewpoint.Pos, pl->height.ZatPoint(viewport->viewpoint.Pos));
+		DVector3 worldP1 = worldP0 + pl->height.Normal();
+		DVector3 viewP0 = viewport->PointWorldToView(worldP0);
+		DVector3 viewP1 = viewport->PointWorldToView(worldP1);
+		planeNormal = viewP1 - viewP0;
+		planeD = -(viewP0 | planeNormal);
+
 		if (Thread->Portal->MirrorFlags & RF_XFLIP)
 			planeNormal.X = -planeNormal.X;
 
@@ -209,11 +212,6 @@ namespace swrenderer
 	{
 		if (r_dynlights)
 		{
-			int tx = x1;
-			bool mirror = !!(Thread->Portal->MirrorFlags & RF_XFLIP);
-			if (mirror)
-				tx = viewwidth - tx - 1;
-
 			// Find row position in view space
 			DVector3 viewposX1 = Thread->Viewport->ScreenToViewPos(x1, y, planeNormal, planeD);
 			DVector3 viewposX2 = Thread->Viewport->ScreenToViewPos(x2, y, planeNormal, planeD);
@@ -229,9 +227,9 @@ namespace swrenderer
 			drawerargs.dc_viewpos.X = viewposX1.X;
 			drawerargs.dc_viewpos.Y = viewposX1.Y;
 			drawerargs.dc_viewpos.Z = viewposX1.Z;
-			drawerargs.dc_viewpos_step.X = viewposX2.X - viewposX1.X;
-			drawerargs.dc_viewpos_step.Y = viewposX2.Y - viewposX1.Y;
-			drawerargs.dc_viewpos_step.Z = viewposX2.Z - viewposX1.Z;
+			drawerargs.dc_viewpos_step.X = (viewposX2.X - viewposX1.X) / (x2 - x1);
+			drawerargs.dc_viewpos_step.Y = (viewposX2.Y - viewposX1.Y) / (x2 - x1);
+			drawerargs.dc_viewpos_step.Z = (viewposX2.Z - viewposX1.Z) / (x2 - x1);
 
 			// Plane normal
 			drawerargs.dc_normal.X = planeNormal.X;
@@ -257,24 +255,22 @@ namespace swrenderer
 			{
 				if (cur_node->lightsource->IsActive())
 				{
-					double lightX = cur_node->lightsource->X() - Thread->Viewport->viewpoint.Pos.X;
-					double lightY = cur_node->lightsource->Y() - Thread->Viewport->viewpoint.Pos.Y;
-					double lightZ = cur_node->lightsource->Z() - Thread->Viewport->viewpoint.Pos.Z;
-
-					float lx = (float)(lightX * Thread->Viewport->viewpoint.Sin - lightY * Thread->Viewport->viewpoint.Cos);
-					float ly = (float)(lightX * Thread->Viewport->viewpoint.TanCos + lightY * Thread->Viewport->viewpoint.TanSin);
-					float lz = (float)lightZ;
+					DVector3 lightPos = Thread->Viewport->PointWorldToView(cur_node->lightsource->Pos);
 
 					uint32_t red = cur_node->lightsource->GetRed();
 					uint32_t green = cur_node->lightsource->GetGreen();
 					uint32_t blue = cur_node->lightsource->GetBlue();
 
 					auto& light = drawerargs.dc_lights[drawerargs.dc_num_lights++];
-					light.x = lx;
-					light.y = ly;
-					light.z = lz;
+					light.x = lightPos.X;
+					light.y = lightPos.Y;
+					light.z = lightPos.Z;
 					light.radius = 256.0f / cur_node->lightsource->GetRadius();
 					light.color = (red << 16) | (green << 8) | blue;
+
+					bool is_point_light = cur_node->lightsource->IsAttenuated();
+					if (is_point_light)
+						light.radius = -light.radius;
 				}
 
 				cur_node = cur_node->next;
diff --git a/src/rendering/swrenderer/viewport/r_viewport.cpp b/src/rendering/swrenderer/viewport/r_viewport.cpp
index 63606d46770..5778951c5e9 100644
--- a/src/rendering/swrenderer/viewport/r_viewport.cpp
+++ b/src/rendering/swrenderer/viewport/r_viewport.cpp
@@ -254,7 +254,7 @@ namespace swrenderer
 		double translatedY = worldPos.Y - viewpoint.Pos.Y;
 		return {
 			translatedX * viewpoint.Sin - translatedY * viewpoint.Cos,
-			translatedX * viewpoint.TanCos + translatedY * viewpoint.TanSin
+			translatedX * viewpoint.Cos + translatedY * viewpoint.Sin
 		};
 	}
 
@@ -266,7 +266,7 @@ namespace swrenderer
 		return {
 			translatedX * viewpoint.Sin - translatedY * viewpoint.Cos,
 			translatedZ,
-			translatedX * viewpoint.TanCos + translatedY * viewpoint.TanSin
+			translatedX * viewpoint.Cos + translatedY * viewpoint.Sin
 		};
 	}