Transparency sorting for DrawList and Materials (#41)

builtin/settingtypes.txt

@@ -805,6 +805,11 @@ autoscale_mode (Autoscaling mode) enum disable disable,enable,force
 #    A restart is required after changing this.
 show_entity_selectionbox (Show entity selection boxes) bool false
 
+#    Sort transparent materials from back to front for proper rendering
+#    Note: works on a per-chunk basis
+#    Note: different materials are sorted independently
+transparency_sorting (Transparency sorting) bool true
+
 [*Menus]
 
 #    Use a cloud animation for the main menu background.

multicraft.conf.example

@@ -939,6 +939,12 @@
 #    type: bool
 # show_entity_selectionbox = false
 
+#    Sort transparent materials from back to front for proper rendering
+#    Note: works on a per-chunk basis
+#    Note: different materials are sorted independently
+#    type: bool
+# transparency_sorting = true
+
 ## Menus
 
 #    Use a cloud animation for the main menu background.

src/client/clientmap.cpp

@@ -88,6 +88,7 @@ ClientMap::ClientMap(
 	m_cache_trilinear_filter  = g_settings->getBool("trilinear_filter");
 	m_cache_bilinear_filter   = g_settings->getBool("bilinear_filter");
 	m_cache_anistropic_filter = g_settings->getBool("anisotropic_filter");
+	m_cache_transparency_sorting = g_settings->getFlag("transparency_sorting");
 
 }
 
@@ -147,8 +148,8 @@ void ClientMap::updateDrawList()
 {
 	ScopeProfiler sp(g_profiler, "CM::updateDrawList()", SPT_AVG);
 
-	for (auto &i : m_drawlist) {
-		MapBlock *block = i.second;
+	for (auto const &i : m_drawlist) {
+		MapBlock *block = i.block;
 		block->refDrop();
 	}
 	m_drawlist.clear();
@@ -247,7 +248,7 @@ void ClientMap::updateDrawList()
 
 			// Add to set
 			block->refGrab();
-			m_drawlist[block->getPos()] = block;
+			m_drawlist.push_back({block, d});
 
 			sector_blocks_drawn++;
 		} // foreach sectorblocks
@@ -256,6 +257,12 @@ void ClientMap::updateDrawList()
 			m_last_drawn_sectors.insert(sp);
 	}
 
+	if (m_drawlist.capacity() > m_drawlist.size() / 4)
+		m_drawlist.shrink_to_fit();
+
+	if (m_cache_transparency_sorting)
+		std::sort(m_drawlist.begin(), m_drawlist.end(), [] (DrawListItem const &a, DrawListItem const &b) { return a.distance > b.distance; });
+
 	g_profiler->avg("MapBlock meshes in range [#]", blocks_in_range_with_mesh);
 	g_profiler->avg("MapBlocks occlusion culled [#]", blocks_occlusion_culled);
 	g_profiler->avg("MapBlocks drawn [#]", m_drawlist.size());
@@ -306,16 +313,11 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 
 	MeshBufListList drawbufs;
 
-	for (auto &i : m_drawlist) {
-		v3s16 block_pos = i.first;
-		MapBlock *block = i.second;
-
-		// If the mesh of the block happened to get deleted, ignore it
-		if (!block->mesh)
-			continue;
-
-		float d = 0.0;
-		if (!isBlockInSight(block->getPos(), camera_position,
+	for (auto &item : m_drawlist) {
+		MapBlock *block = item.block;
+		v3s16 block_pos = block->getPos();
+		float d;
+		if (!isBlockInSight(block_pos, camera_position,
 				camera_direction, camera_fov, 100000 * BS, &d))
 			continue;
 
@@ -387,6 +389,14 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 
 	// Render all layers in order
 	for (auto &lists : drawbufs.lists) {
+		if (m_cache_transparency_sorting) {
+			static const auto comparator = [] (MeshBufList const &a, MeshBufList const &b) {
+				// comparing pointers with < is UB unless they belong to the same array, but std::less is always allowed
+				static const std::less<video::ITexture *> texture_less;
+				return texture_less(a.m.TextureLayer[0].Texture, b.m.TextureLayer[0].Texture);
+			};
+			std::sort(lists.begin(), lists.end(), comparator);
+		}
 		for (MeshBufList &list : lists) {
 			// Check and abort if the machine is swapping a lot
 			if (draw.getTimerTime() > 2000) {

src/client/clientmap.h

@@ -55,6 +55,11 @@ struct MeshBufListList
 	void add(scene::IMeshBuffer *buf, v3s16 position, u8 layer);
 };
 
+struct DrawListItem {
+	MapBlock *block;
+	float distance;
+};
+
 class Client;
 class ITextureSource;
 
@@ -146,11 +151,12 @@ private:
 	f32 m_camera_fov = M_PI;
 	v3s16 m_camera_offset;
 
-	std::map<v3s16, MapBlock*> m_drawlist;
+	std::vector<DrawListItem> m_drawlist;
 
 	std::set<v2s16> m_last_drawn_sectors;
 
 	bool m_cache_trilinear_filter;
 	bool m_cache_bilinear_filter;
 	bool m_cache_anistropic_filter;
+	bool m_cache_transparency_sorting;
 };

src/defaultsettings.cpp

@@ -245,6 +245,7 @@ void set_default_settings()
 	settings->setDefault("round_screen", "0");
 	settings->setDefault("enable_local_map_saving", "false");
 	settings->setDefault("show_entity_selectionbox", "false");
+	settings->setDefault("transparency_sorting", "true");
 	settings->setDefault("texture_clean_transparent", "false");
 	settings->setDefault("texture_min_size", "0");
 	settings->setDefault("ambient_occlusion_gamma", "2.2");

src/util/numeric.cpp

@@ -123,18 +123,18 @@ bool isBlockInSight(v3s16 blockpos_b, v3f camera_pos, v3f camera_dir,
 	v3f blockpos_relative = blockpos - camera_pos;
 
 	// Total distance
-	f32 d = MYMAX(0, blockpos_relative.getLength() - block_max_radius);
+	f32 d = blockpos_relative.getLength();
 
 	if (distance_ptr)
 		*distance_ptr = d;
 
 	// If block is far away, it's not in sight
-	if (d > range)
+	if (d > range + block_max_radius)
 		return false;
 
 	// If block is (nearly) touching the camera, don't
 	// bother validating further (that is, render it anyway)
-	if (d == 0)
+	if (d <= block_max_radius)
 		return true;
 
 	// Adjust camera position, for purposes of computing the angle,