diff --git a/src/polyrenderer/scene/poly_decal.cpp b/src/polyrenderer/scene/poly_decal.cpp
index d619c13f5..6ffd24439 100644
--- a/src/polyrenderer/scene/poly_decal.cpp
+++ b/src/polyrenderer/scene/poly_decal.cpp
@@ -52,92 +52,132 @@ void RenderPolyDecal::Render(const TriMatrix &worldToClip, const PolyClipPlane &
 	if (tex == nullptr || tex->UseType == FTexture::TEX_Null)
 		return;
 
-	double edge_right = tex->GetWidth();
-	double edge_left = tex->LeftOffset;
-	edge_right = (edge_right - edge_left) * decal->ScaleX;
-	edge_left *= decal->ScaleX;
+	sector_t *front, *back;
+	GetDecalSectors(decal, line, &front, &back);
 
-	double dcx, dcy;
-	decal->GetXY(line->sidedef, dcx, dcy);
-	DVector2 decal_pos = { dcx, dcy };
+	// Calculate unclipped position and UV coordinates
+
+	double edge_left = tex->LeftOffset * decal->ScaleX;
+	double edge_right = (tex->GetWidth() - tex->LeftOffset) * decal->ScaleX;
 
 	DVector2 angvec = (line->v2->fPos() - line->v1->fPos()).Unit();
 	DVector2 normal = { angvec.Y, -angvec.X };
 
-	decal_pos += normal;
-
+	double dcx, dcy;
+	decal->GetXY(line->sidedef, dcx, dcy);
+	DVector2 decal_pos = DVector2(dcx, dcy) + normal;
 	DVector2 decal_left = decal_pos - edge_left * angvec;
 	DVector2 decal_right = decal_pos + edge_right * angvec;
 
-	// Determine actor z
-	double zpos = decal->Z;
-	sector_t *back = (line->backsector != nullptr) ? line->backsector : line->frontsector;
+	bool flipTextureX = (decal->RenderFlags & RF_XFLIP) == RF_XFLIP;
+	double u_left = flipTextureX ? 1.0 : 0.0;
+	double u_right = flipTextureX ? 1.0 - tex->Scale.X : tex->Scale.X;
+	double u_unit = (u_right - u_left) / (edge_left + edge_right);
 
-	// for 3d-floor segments use the model sector as reference
-	sector_t *front;
-	if ((decal->RenderFlags&RF_CLIPMASK) == RF_CLIPMID) front = decal->Sector;
-	else front = line->frontsector;
+	double zpos = GetDecalZ(decal, line, front, back);
+	double spriteHeight = decal->ScaleY / tex->Scale.Y * tex->GetHeight();
+	double ztop = zpos + spriteHeight - spriteHeight * 0.5;
+	double zbottom = zpos - spriteHeight * 0.5;
 
-	switch (decal->RenderFlags & RF_RELMASK)
+	double v_top = 0.0;
+	double v_bottom = tex->Scale.Y;
+	double v_unit = (v_bottom - v_top) / (zbottom - ztop);
+
+	// Clip decal to wall part
+
+	double walltopz, wallbottomz;
+	GetWallZ(decal, line, front, back, walltopz, wallbottomz);
+
+	double clip_left_v1 = (decal_left - line->v1->fPos()) | angvec;
+	double clip_right_v1 = (decal_right - line->v1->fPos()) | angvec;
+	double clip_left_v2 = (decal_left - line->v2->fPos()) | angvec;
+	double clip_right_v2 = (decal_right - line->v2->fPos()) | angvec;
+
+	if ((clip_left_v1 <= 0.0 && clip_right_v1 <= 0.0) || (clip_left_v2 >= 0.0 && clip_right_v2 >= 0.0))
+		return;
+
+	if (clip_left_v1 < 0.0)
 	{
-	default:
-		zpos = decal->Z;
-		break;
-	case RF_RELUPPER:
-		if (line->linedef->flags & ML_DONTPEGTOP)
-			zpos = decal->Z + front->GetPlaneTexZ(sector_t::ceiling);
-		else
-			zpos = decal->Z + back->GetPlaneTexZ(sector_t::ceiling);
-		break;
-	case RF_RELLOWER:
-		if (line->linedef->flags & ML_DONTPEGBOTTOM)
-			zpos = decal->Z + front->GetPlaneTexZ(sector_t::ceiling);
-		else
-			zpos = decal->Z + back->GetPlaneTexZ(sector_t::floor);
-		break;
-	case RF_RELMID:
-		if (line->linedef->flags & ML_DONTPEGBOTTOM)
-			zpos = decal->Z + front->GetPlaneTexZ(sector_t::floor);
-		else
-			zpos = decal->Z + front->GetPlaneTexZ(sector_t::ceiling);
+		decal_left -= angvec * clip_left_v1;
+		u_left -= u_unit * clip_left_v1;
+	}
+	if (clip_right_v1 < 0.0)
+	{
+		decal_right -= angvec * clip_right_v1;
+		u_right -= u_unit * clip_right_v1;
+	}
+	if (clip_left_v2 > 0.0)
+	{
+		decal_left -= angvec * clip_left_v2;
+		u_left -= u_unit * clip_left_v2;
+	}
+	if (clip_right_v2 > 0.0)
+	{
+		decal_right -= angvec * clip_right_v2;
+		u_right -= u_unit * clip_right_v2;
 	}
 
-	DVector2 spriteScale = { decal->ScaleX, decal->ScaleY };
-	double thingxscalemul = spriteScale.X / tex->Scale.X;
-	double thingyscalemul = spriteScale.Y / tex->Scale.Y;
-	double spriteHeight = thingyscalemul * tex->GetHeight();
+	double clip_top_floor = ztop - wallbottomz;
+	double clip_bottom_floor = zbottom - wallbottomz;
+	double clip_top_ceiling = ztop - walltopz;
+	double clip_bottom_ceiling = zbottom - walltopz;
 
-	bool flipTextureX = (decal->RenderFlags & RF_XFLIP) == RF_XFLIP;
+	if ((clip_top_floor <= 0.0 && clip_bottom_floor <= 0.0) || (clip_top_ceiling >= 0.0 && clip_bottom_ceiling >= 0.0))
+		return;
 
-	DVector2 points[2] = { decal_left, decal_right };
+	if (clip_top_floor < 0.0)
+	{
+		ztop -= clip_top_floor;
+		v_top -= v_unit * clip_top_floor;
+	}
+	if (clip_bottom_floor < 0.0)
+	{
+		zbottom -= clip_bottom_floor;
+		v_bottom -= v_unit * clip_bottom_floor;
+	}
+	if (clip_top_ceiling > 0.0)
+	{
+		ztop -= clip_top_ceiling;
+		v_top -= v_unit * clip_top_ceiling;
+	}
+	if (clip_bottom_ceiling > 0.0)
+	{
+		zbottom -= clip_bottom_ceiling;
+		v_bottom -= v_unit * clip_bottom_ceiling;
+	}
+
+	// Generate vertices for the decal
 
 	TriVertex *vertices = PolyRenderer::Instance()->FrameMemory.AllocMemory<TriVertex>(4);
+	vertices[0].x = (float)decal_left.X;
+	vertices[0].y = (float)decal_left.Y;
+	vertices[0].z = (float)ztop;
+	vertices[0].w = 1.0f;
+	vertices[0].u = (float)u_left;
+	vertices[0].v = (float)v_top;
+	vertices[1].x = (float)decal_right.X;
+	vertices[1].y = (float)decal_right.Y;
+	vertices[1].z = (float)ztop;
+	vertices[1].w = 1.0f;
+	vertices[1].u = (float)u_right;
+	vertices[1].v = (float)v_top;
+	vertices[2].x = (float)decal_right.X;
+	vertices[2].y = (float)decal_right.Y;
+	vertices[2].z = (float)zbottom;
+	vertices[2].w = 1.0f;
+	vertices[2].u = (float)u_right;
+	vertices[2].v = (float)v_bottom;
+	vertices[3].x = (float)decal_left.X;
+	vertices[3].y = (float)decal_left.Y;
+	vertices[3].z = (float)zbottom;
+	vertices[3].w = 1.0f;
+	vertices[3].u = (float)u_left;
+	vertices[3].v = (float)v_bottom;
+
+	// Light calculations
 
 	bool foggy = false;
 	int actualextralight = foggy ? 0 : PolyRenderer::Instance()->Viewpoint.extralight << 4;
-
-	std::pair<float, float> offsets[4] =
-	{
-		{ 0.0f,  1.0f },
-		{ 1.0f,  1.0f },
-		{ 1.0f,  0.0f },
-		{ 0.0f,  0.0f },
-	};
-
-	for (int i = 0; i < 4; i++)
-	{
-		auto &p = (i == 0 || i == 3) ? points[0] : points[1];
-
-		vertices[i].x = (float)p.X;
-		vertices[i].y = (float)p.Y;
-		vertices[i].z = (float)(zpos + spriteHeight * offsets[i].second - spriteHeight * 0.5);
-		vertices[i].w = 1.0f;
-		vertices[i].u = (float)(offsets[i].first * tex->Scale.X);
-		vertices[i].v = (float)((1.0f - offsets[i].second) * tex->Scale.Y);
-		if (flipTextureX)
-			vertices[i].u = 1.0f - vertices[i].u;
-	}
-
 	bool fullbrightSprite = (decal->RenderFlags & RF_FULLBRIGHT) == RF_FULLBRIGHT;
 	int lightlevel = fullbrightSprite ? 255 : front->lightlevel + actualextralight;
 
@@ -155,3 +195,90 @@ void RenderPolyDecal::Render(const TriMatrix &worldToClip, const PolyClipPlane &
 	args.SetWriteDepth(false);
 	args.DrawArray(vertices, 4, PolyDrawMode::TriangleFan);
 }
+
+void RenderPolyDecal::GetDecalSectors(DBaseDecal *decal, const seg_t *line, sector_t **front, sector_t **back)
+{
+	// for 3d-floor segments use the model sector as reference
+	if ((decal->RenderFlags&RF_CLIPMASK) == RF_CLIPMID)
+		*front = decal->Sector;
+	else
+		*front = line->frontsector;
+
+	*back = (line->backsector != nullptr) ? line->backsector : line->frontsector;
+}
+
+double RenderPolyDecal::GetDecalZ(DBaseDecal *decal, const seg_t *line, sector_t *front, sector_t *back)
+{
+	switch (decal->RenderFlags & RF_RELMASK)
+	{
+	default:
+		return decal->Z;
+	case RF_RELUPPER:
+		if (line->linedef->flags & ML_DONTPEGTOP)
+			return decal->Z + front->GetPlaneTexZ(sector_t::ceiling);
+		else
+			return decal->Z + back->GetPlaneTexZ(sector_t::ceiling);
+	case RF_RELLOWER:
+		if (line->linedef->flags & ML_DONTPEGBOTTOM)
+			return decal->Z + front->GetPlaneTexZ(sector_t::ceiling);
+		else
+			return decal->Z + back->GetPlaneTexZ(sector_t::floor);
+		break;
+	case RF_RELMID:
+		if (line->linedef->flags & ML_DONTPEGBOTTOM)
+			return decal->Z + front->GetPlaneTexZ(sector_t::floor);
+		else
+			return decal->Z + front->GetPlaneTexZ(sector_t::ceiling);
+	}
+}
+
+void RenderPolyDecal::GetWallZ(DBaseDecal *decal, const seg_t *line, sector_t *front, sector_t *back, double &walltopz, double &wallbottomz)
+{
+	double frontceilz1 = front->ceilingplane.ZatPoint(line->v1);
+	double frontfloorz1 = front->floorplane.ZatPoint(line->v1);
+	double frontceilz2 = front->ceilingplane.ZatPoint(line->v2);
+	double frontfloorz2 = front->floorplane.ZatPoint(line->v2);
+	if (back == nullptr)
+	{
+		walltopz = MAX(frontceilz1, frontceilz2);
+		wallbottomz = MIN(frontfloorz1, frontfloorz2);
+	}
+	else
+	{
+		double backceilz1 = back->ceilingplane.ZatPoint(line->v1);
+		double backfloorz1 = back->floorplane.ZatPoint(line->v1);
+		double backceilz2 = back->ceilingplane.ZatPoint(line->v2);
+		double backfloorz2 = back->floorplane.ZatPoint(line->v2);
+		double topceilz1 = frontceilz1;
+		double topceilz2 = frontceilz2;
+		double topfloorz1 = MAX(MIN(backceilz1, frontceilz1), frontfloorz1);
+		double topfloorz2 = MAX(MIN(backceilz2, frontceilz2), frontfloorz2);
+		double bottomceilz1 = MIN(MAX(frontfloorz1, backfloorz1), frontceilz1);
+		double bottomceilz2 = MIN(MAX(frontfloorz2, backfloorz2), frontceilz2);
+		double bottomfloorz1 = frontfloorz1;
+		double bottomfloorz2 = frontfloorz2;
+		double middleceilz1 = topfloorz1;
+		double middleceilz2 = topfloorz2;
+		double middlefloorz1 = MIN(bottomceilz1, middleceilz1);
+		double middlefloorz2 = MIN(bottomceilz2, middleceilz2);
+
+		switch (decal->RenderFlags & RF_RELMASK)
+		{
+		default:
+			walltopz = MAX(frontceilz1, frontceilz2);
+			wallbottomz = MIN(frontfloorz1, frontfloorz2);
+			break;
+		case RF_RELUPPER:
+			walltopz = MAX(topceilz1, topceilz2);
+			wallbottomz = MIN(topfloorz1, topfloorz2);
+			break;
+		case RF_RELLOWER:
+			walltopz = MAX(bottomceilz1, bottomceilz2);
+			wallbottomz = MIN(bottomfloorz1, bottomfloorz2);
+			break;
+		case RF_RELMID:
+			walltopz = MAX(middleceilz1, middleceilz2);
+			wallbottomz = MIN(middlefloorz1, middlefloorz2);
+		}
+	}
+}
diff --git a/src/polyrenderer/scene/poly_decal.h b/src/polyrenderer/scene/poly_decal.h
index 0cab330ca..b10e8a6b0 100644
--- a/src/polyrenderer/scene/poly_decal.h
+++ b/src/polyrenderer/scene/poly_decal.h
@@ -31,4 +31,8 @@ public:
 
 private:
 	void Render(const TriMatrix &worldToClip, const PolyClipPlane &clipPlane, DBaseDecal *decal, const seg_t *line, uint32_t stencilValue);
+
+	void GetDecalSectors(DBaseDecal *decal, const seg_t *line, sector_t **front, sector_t **back);
+	double GetDecalZ(DBaseDecal *decal, const seg_t *line, sector_t *front, sector_t *back);
+	void GetWallZ(DBaseDecal *decal, const seg_t *line, sector_t *front, sector_t *back, double &walltopz, double &wallbottomz);
 };