Improve block bounds HUD feature

* Use different material than selection box, so it doesn't break
  for non-default `node_highlighting` values.
* Add `show_block_bounds_radius_near` setting.
* Draw mesh chunk edges in a different color (red vs yellow).

builtin/settingtypes.txt

@@ -735,6 +735,12 @@ hud_scaling (HUD scaling) float 1.0 0.5 20
 #    Mods may still set a background.
 show_nametag_backgrounds (Show name tag backgrounds by default) bool true
 
+#    Whether to show the client debug info (has the same effect as hitting F5).
+show_debug (Show debug info) bool false
+
+#    Radius to use when the block bounds HUD feature is set to near blocks.
+show_block_bounds_radius_near (Block bounds HUD radius) int 4 0 1000
+
 [**Chat]
 
 #    Maximum number of recent chat messages to show
@@ -2009,9 +2015,6 @@ client_unload_unused_data_timeout (Mapblock unload timeout) float 600.0 0.0
 #    Set to -1 for unlimited amount.
 client_mapblock_limit (Mapblock limit) int 7500 -1 2147483647
 
-#    Whether to show the client debug info (has the same effect as hitting F5).
-show_debug (Show debug info) bool false
-
 #    Maximum number of blocks that are simultaneously sent per client.
 #    The maximum total count is calculated dynamically:
 #    max_total = ceil((#clients + max_users) * per_client / 4)

src/client/hud.cpp

@@ -97,6 +97,8 @@ Hud::Hud(Client *client, LocalPlayer *player,
 		m_mode = HIGHLIGHT_BOX;
 	}
 
+	// Initialize m_selection_material
+
 	m_selection_material.Lighting = false;
 
 	if (g_settings->getBool("enable_shaders")) {
@@ -118,6 +120,18 @@ Hud::Hud(Client *client, LocalPlayer *player,
 		m_selection_material.MaterialType = video::EMT_SOLID;
 	}
 
+	// Initialize m_block_bounds_material
+	m_block_bounds_material.Lighting = false;
+	if (g_settings->getBool("enable_shaders")) {
+		IShaderSource *shdrsrc = client->getShaderSource();
+		auto shader_id = shdrsrc->getShader("default_shader", TILE_MATERIAL_ALPHA);
+		m_block_bounds_material.MaterialType = shdrsrc->getShaderInfo(shader_id).material;
+	} else {
+		m_block_bounds_material.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL;
+	}
+	m_block_bounds_material.Thickness =
+			rangelim(g_settings->getS16("selectionbox_width"), 1, 5);
+
 	// Prepare mesh for compass drawing
 	auto &b = m_rotation_mesh_buffer;
 	b.Vertices.resize(4);
@@ -934,33 +948,57 @@ void Hud::drawBlockBounds()
 	}
 
 	video::SMaterial old_material = driver->getMaterial2D();
-	driver->setMaterial(m_selection_material);
+	driver->setMaterial(m_block_bounds_material);
+
+	u16 mesh_chunk_size = std::max<u16>(1, g_settings->getU16("client_mesh_chunk"));
 
 	v3s16 pos = player->getStandingNodePos();
-
-	v3s16 blockPos(
+	v3s16 block_pos(
 		floorf((float) pos.X / MAP_BLOCKSIZE),
 		floorf((float) pos.Y / MAP_BLOCKSIZE),
 		floorf((float) pos.Z / MAP_BLOCKSIZE)
 	);
 
-	v3f offset = intToFloat(client->getCamera()->getOffset(), BS);
+	v3f cam_offset = intToFloat(client->getCamera()->getOffset(), BS);
 
-	s8 radius = m_block_bounds_mode == BLOCK_BOUNDS_NEAR ? 2 : 0;
+	v3f half_node = v3f(BS, BS, BS) / 2.0f;
+	v3f base_corner = intToFloat(block_pos * MAP_BLOCKSIZE, BS) - cam_offset - half_node;
 
-	v3f halfNode = v3f(BS, BS, BS) / 2.0f;
+	s16 radius = m_block_bounds_mode == BLOCK_BOUNDS_NEAR ?
+			rangelim(g_settings->getU16("show_block_bounds_radius_near"), 0, 1000) : 0;
 
-	for (s8 x = -radius; x <= radius; x++)
-	for (s8 y = -radius; y <= radius; y++)
-	for (s8 z = -radius; z <= radius; z++) {
-		v3s16 blockOffset(x, y, z);
+	for (s16 x = -radius; x <= radius + 1; x++)
+	for (s16 y = -radius; y <= radius + 1; y++) {
+		// Red for mesh chunk edges, yellow for other block edges.
+		auto choose_color = [&](s16 x_base, s16 y_base) {
+			// See also MeshGrid::isMeshPos().
+			// If the block is mesh pos, it means it's at the (-,-,-) corner of
+			// the mesh. And we're drawing a (-,-) edge of this block. Hence,
+			// it is an edge of the mesh grid.
+			return (x + x_base) % mesh_chunk_size == 0
+					&& (y + y_base) % mesh_chunk_size == 0 ?
+				video::SColor(255, 255, 0, 0) :
+				video::SColor(255, 255, 255, 0);
+		};
 
-		aabb3f box(
-			intToFloat((blockPos + blockOffset) * MAP_BLOCKSIZE, BS) - offset - halfNode,
-			intToFloat(((blockPos + blockOffset) * MAP_BLOCKSIZE) + (MAP_BLOCKSIZE - 1), BS) - offset + halfNode
+		v3f pmin = v3f(x, y,    -radius) * MAP_BLOCKSIZE * BS;
+		v3f pmax = v3f(x, y, 1 + radius) * MAP_BLOCKSIZE * BS;
+
+		driver->draw3DLine(
+			base_corner + v3f(pmin.X, pmin.Y, pmin.Z),
+			base_corner + v3f(pmax.X, pmax.Y, pmax.Z),
+			choose_color(block_pos.X, block_pos.Y)
+		);
+		driver->draw3DLine(
+			base_corner + v3f(pmin.X, pmin.Z, pmin.Y),
+			base_corner + v3f(pmax.X, pmax.Z, pmax.Y),
+			choose_color(block_pos.X, block_pos.Z)
+		);
+		driver->draw3DLine(
+			base_corner + v3f(pmin.Z, pmin.X, pmin.Y),
+			base_corner + v3f(pmax.Z, pmax.X, pmax.Y),
+			choose_color(block_pos.Y, block_pos.Z)
 		);
-
-		driver->draw3DBox(box, video::SColor(255, 255, 0, 0));
 	}
 
 	driver->setMaterial(old_material);

src/client/hud.h

@@ -137,6 +137,7 @@ private:
 	v3f m_selected_face_normal;
 
 	video::SMaterial m_selection_material;
+	video::SMaterial m_block_bounds_material;
 
 	scene::SMeshBuffer m_rotation_mesh_buffer;
 

src/defaultsettings.cpp

@@ -302,6 +302,7 @@ void set_default_settings()
 	settings->setDefault("enable_particles", "true");
 	settings->setDefault("arm_inertia", "true");
 	settings->setDefault("show_nametag_backgrounds", "true");
+	settings->setDefault("show_block_bounds_radius_near", "4");
 	settings->setDefault("transparency_sorting_distance", "16");
 
 	settings->setDefault("enable_minimap", "true");