- use an indexed vertex buffer to render the flats.

Right now this has no advantage but it allows optimizing the data, e.g. rendering an entire sector in one go instead of per subsector.

src/hwrenderer/data/flatvertices.cpp

@@ -181,10 +181,9 @@ int FFlatVertexGenerator::CreateVertices(int h, sector_t *sec, const secplane_t
 
 			if (dotop || dobottom)
 			{
-				if (dotop) ffloor->top.vindex = vbo_shadowdata.Size();
-				if (dobottom) ffloor->bottom.vindex = vbo_shadowdata.Size();
-	
-				CreateSectorVertices(fsec, plane, false);
+				auto ndx = CreateSectorVertices(fsec, plane, false);
+				if (dotop) ffloor->top.vindex = ndx;
+				if (dobottom) ffloor->bottom.vindex = ndx;
 			}
 		}
 	}
@@ -227,6 +226,147 @@ void FFlatVertexGenerator::CreateFlatVertices()
 	}
 }
 
+//==========================================================================
+//
+// Creates the vertices for one plane in one subsector
+//
+//==========================================================================
+
+int FFlatVertexGenerator::CreateIndexedSubsectorVertices(subsector_t *sub, const secplane_t &plane, int floor, int vi, FFlatVertexGenerator::FIndexGenerationInfo &gen)
+{
+	int idx = ibo_data.Reserve(sub->numlines);
+	for (unsigned int k = 0; k<sub->numlines; k++)
+	{
+		auto ndx = gen.GetIndex(sub->firstline[k].v1);
+		ibo_data[idx + k] = vi + ndx;
+	}
+	return idx;
+}
+
+//==========================================================================
+//
+// Creates the vertices for one plane in one subsector
+//
+//==========================================================================
+
+int FFlatVertexGenerator::CreateIndexedSectorVertices(sector_t *sec, const secplane_t &plane, int floor, FFlatVertexGenerator::FIndexGenerationInfo &gen)
+{
+	int rt = ibo_data.Size();
+	int vi = vbo_shadowdata.Reserve(gen.vertices.Size());
+	float diff;
+
+	// Create the actual vertices.
+	if (sec->transdoor && floor) diff = -1.f;
+	else diff = 0.f;
+	for (unsigned i = 0; i < gen.vertices.Size(); i++)
+	{
+		vbo_shadowdata[vi + i].SetFlatVertex(gen.vertices[i], plane);
+		vbo_shadowdata[vi + i].z += diff;
+	}
+	
+	// Create the indices for the subsectors
+	for (int j = 0; j<sec->subsectorcount; j++)
+	{
+		subsector_t *sub = sec->subsectors[j];
+		CreateIndexedSubsectorVertices(sub, plane, floor, vi, gen);
+	}
+	return rt;
+}
+
+//==========================================================================
+//
+//
+//
+//==========================================================================
+
+int FFlatVertexGenerator::CreateIndexedVertices(int h, sector_t *sec, const secplane_t &plane, int floor, TArray<FFlatVertexGenerator::FIndexGenerationInfo> &gen)
+{
+	// First calculate the vertices for the sector itself
+	sec->vboheight[h] = sec->GetPlaneTexZ(h);
+	sec->vboindex[h] = CreateIndexedSectorVertices(sec, plane, floor, gen[sec->Index()]);
+
+	// Next are all sectors using this one as heightsec
+	TArray<sector_t *> &fakes = sec->e->FakeFloor.Sectors;
+	for (unsigned g = 0; g<fakes.Size(); g++)
+	{
+		sector_t *fsec = fakes[g];
+		fsec->vboindex[2 + h] = CreateIndexedSectorVertices(fsec, plane, false, gen[fsec->Index()]);
+	}
+
+	// and finally all attached 3D floors
+	TArray<sector_t *> &xf = sec->e->XFloor.attached;
+	for (unsigned g = 0; g<xf.Size(); g++)
+	{
+		sector_t *fsec = xf[g];
+		F3DFloor *ffloor = Find3DFloor(fsec, sec);
+
+		if (ffloor != NULL && ffloor->flags & FF_RENDERPLANES)
+		{
+			bool dotop = (ffloor->top.model == sec) && (ffloor->top.isceiling == h);
+			bool dobottom = (ffloor->bottom.model == sec) && (ffloor->bottom.isceiling == h);
+
+			if (dotop || dobottom)
+			{
+				auto ndx = CreateIndexedSectorVertices(fsec, plane, false, gen[fsec->Index()]);
+				if (dotop) ffloor->top.vindex = ndx;
+				if (dobottom) ffloor->bottom.vindex = ndx;
+			}
+		}
+	}
+	sec->vbocount[h] = vbo_shadowdata.Size() - sec->vboindex[h];
+	return sec->vboindex[h];
+}
+
+
+//==========================================================================
+//
+//
+//
+//==========================================================================
+
+void FFlatVertexGenerator::CreateIndexedFlatVertices()
+{
+	TArray<FIndexGenerationInfo> gen;
+	gen.Resize(level.sectors.Size());
+	// This must be generated up front so that the following code knows how many vertices a sector contains.
+	for (unsigned i = 0; i < level.sectors.Size(); i++)
+	{
+		for (int j = 0; j < level.sectors[i].subsectorcount; j++)
+		{
+			auto sub = level.sectors[i].subsectors[j];
+			for (unsigned k = 0; k < sub->numlines; k++)
+			{
+				auto vert = sub->firstline[k].v1;
+				gen[i].AddVertex(vert);
+			}
+		}
+	}
+	for (int h = sector_t::floor; h <= sector_t::ceiling; h++)
+	{
+		for (auto &sec : level.sectors)
+		{
+			CreateIndexedVertices(h, &sec, sec.GetSecPlane(h), h == sector_t::floor, gen);
+		}
+	}
+
+	// We need to do a final check for Vavoom water and FF_FIX sectors.
+	// No new vertices are needed here. The planes come from the actual sector
+	for (auto &sec : level.sectors)
+	{
+		for (auto ff : sec.e->XFloor.ffloors)
+		{
+			if (ff->top.model == &sec)
+			{
+				ff->top.vindex = sec.vboindex[ff->top.isceiling];
+			}
+			if (ff->bottom.model == &sec)
+			{
+				ff->bottom.vindex = sec.vboindex[ff->top.isceiling];
+			}
+		}
+	}
+}
+
 //==========================================================================
 //
 //
@@ -257,7 +397,7 @@ void FFlatVertexGenerator::UpdatePlaneVertices(sector_t *sec, int plane, FFlatVe
 void FFlatVertexGenerator::CreateVertices()
 {
 	vbo_shadowdata.Resize(NUM_RESERVED);
-	CreateFlatVertices();
+	CreateIndexedFlatVertices();
 }
 
 //==========================================================================