feat(editor): zoomed in from above, the curves are labelled with their radius and length and the switches with their name and type

In the top view at a metre a pixel or closer, each curved track of 5 m or more gets "R 600  L 120" by its middle and each
switch its name and its type from the kept switch record ("Rz 60E1-300-1:9 P") by its start, on a dark plate as on a plan.
A label which would cover another one is left out, the switches going first and then the sharper curves. View > Track labels
in the top view switches them off.

application/editormode.cpp

@@ -1460,6 +1460,7 @@ bool editor_mode::update()
     if (ui()->mode() == nodebank_panel::TRACK)
     {
         draw_track_lines();
+        draw_track_labels();
         draw_track_legend();
     }
     if (selected_track())
@@ -3592,6 +3593,9 @@ void editor_mode::render_view_menu()
     }
     if (ImGui::IsItemHovered())
         ImGui::SetTooltip("%s", STR_C("The tracks of the track mode coloured by their radius, speed or grade, with the legend in the corner"));
+    ImGui::MenuItem(STR_C("Track labels in the top view"), nullptr, &m_track_labels);
+    if (ImGui::IsItemHovered())
+        ImGui::SetTooltip("%s", STR_C("Zoomed in from above, the curves get their radius and length and the switches their name and type, as on a plan; where they'd crowd, some are left out"));
     ImGui::MenuItem(STR_C("Show lanes"), nullptr, &m_roadtool.lanes);
     if (ImGui::IsItemHovered())
         ImGui::SetTooltip("%s", STR_C("The lanes of the roads drawn as the paths the vehicles take"));

application/editormode.h

@@ -1574,6 +1574,9 @@ class editor_mode : public application_mode, private editor_track::observer, pri
 	enum class track_colouring { plain, radius, speed, grade };
 	track_colouring m_track_colouring{track_colouring::plain};
 	void draw_track_legend() const;
+	// the radii and lengths of the curves and the names and types of the switches written by them, from above, as on a plan
+	bool m_track_labels{true};
+	void draw_track_labels() const;
 	void draw_track_hover() const;
 	struct track_intent
 	{

application/editormodetrackux.cpp

@@ -15,6 +15,7 @@ http://mozilla.org/MPL/2.0/.
 #include "application/editormodetrackshared.h"
 #include "editor/editorFormat.hpp"
 #include "editor/editorGeometry.hpp"
+#include "editor/editorSwitchStore.hpp"
 
 #include "utilities/Globals.h"
 #include "rendering/renderer.h"
@@ -93,6 +94,8 @@ struct colour_band
 double constexpr kBeyond{std::numeric_limits<double>::max()};
 ImU32 const kUncoloured{IM_COL32(200, 200, 200, 170)};
 double const kColouredReach{1500.0}; // m around the camera in the 3D view
+double const kLabelsTo{1.0}; // m a pixel of the top view, farther out the labels of the tracks are left out
+double const kLabelledLength{5.0}; // m, shorter curves get no label
 std::vector<colour_band> const kRadiusBands{{300.0, IM_COL32(235, 60, 60, 235), "R < 300 m"}, {600.0, IM_COL32(245, 140, 50, 235), "R 300-600 m"}, {1200.0, IM_COL32(240, 220, 60, 235), "R 600-1200 m"},
                                             {3000.0, IM_COL32(110, 210, 80, 235), "R 1200-3000 m"}, {kBeyond, IM_COL32(70, 190, 235, 235), "R > 3000 m"}};
 std::vector<colour_band> const kSpeedBands{{40.5, IM_COL32(235, 60, 60, 235), "<= 40 km/h"}, {60.5, IM_COL32(245, 140, 50, 235), "50-60 km/h"}, {80.5, IM_COL32(240, 220, 60, 235), "70-80 km/h"},
@@ -243,6 +246,66 @@ void editor_mode::draw_track_lines() const
 	}
 }
 
+void editor_mode::draw_track_labels() const
+{
+	auto const metres{ortho_metres_per_pixel()};
+	if (false == m_track_labels || metres <= 0.0 || metres > kLabelsTo)
+		return;
+	auto const &io{ImGui::GetIO()};
+	screen_projection const projection;
+	glm::dvec2 const centre{Global.pCamera.Pos.x, Global.pCamera.Pos.z};
+	auto const reach{0.5 * metres * std::hypot(static_cast<double>(io.DisplaySize.x), static_cast<double>(io.DisplaySize.y))};
+	auto *drawlist{ImGui::GetBackgroundDrawList(ImGui::GetMainViewport())};
+	auto const low{editor_ui::view_min()};
+	auto const high{editor_ui::view_max()};
+	// a label which would cover another one is left out: the switches go first, then the sharper curves
+	std::vector<std::pair<ImVec2, ImVec2>> taken;
+	auto const write = [&](glm::dvec3 const &Point, std::string const &Text, ImU32 const Colour) {
+		ImVec2 at;
+		if (false == projection.project(Point, at))
+			return;
+		auto const size{ImGui::CalcTextSize(Text.c_str())};
+		ImVec2 const from{at.x - size.x * 0.5f - 4.0f, at.y - size.y - 12.0f};
+		ImVec2 const to{at.x + size.x * 0.5f + 4.0f, at.y - 8.0f};
+		if (from.x < low.x || from.y < low.y || to.x > high.x || to.y > high.y)
+			return;
+		if (std::any_of(taken.begin(), taken.end(), [&](auto const &Rect) { return from.x < Rect.second.x + 6.0f && to.x > Rect.first.x - 6.0f && from.y < Rect.second.y + 3.0f && to.y > Rect.first.y - 3.0f; }))
+			return;
+		taken.emplace_back(from, to);
+		drawlist->AddRectFilled(from, to, IM_COL32(0, 0, 0, 165), 3.0f);
+		drawlist->AddText(ImVec2(from.x + 4.0f, from.y), Colour, Text.c_str());
+	};
+	struct curve_label
+	{
+		double radius;
+		glm::dvec3 point;
+		std::string text;
+	};
+	std::vector<curve_label> curves;
+	for (auto *track : simulation::Paths.sequence())
+	{
+		if (track == nullptr || false == rail(*track) || track->m_paths.empty())
+			continue;
+		bezier const first{track->m_paths.front()};
+		if (false == plan_near(first, centre, reach))
+			continue;
+		if (track->eType == tt_Switch)
+		{
+			auto text{name_of(*track)};
+			if (auto const record{switch_store::of(*track)})
+				text += "  " + switch_store::label(*record);
+			write(first.point(0.0), text, IM_COL32(255, 220, 120, 255));
+			continue;
+		}
+		auto const radius{::track_mode::piece_plan_radius(track->m_paths.front())};
+		if (radius >= 0.5 && first.plan_length() >= kLabelledLength)
+			curves.push_back({radius, first.point(0.5), format("R %.0f  L %.1f", radius, first.plan_length())});
+	}
+	std::sort(curves.begin(), curves.end(), [](curve_label const &A, curve_label const &B) { return A.radius < B.radius; });
+	for (auto const &curve : curves)
+		write(curve.point, curve.text, IM_COL32(235, 235, 235, 240));
+}
+
 void editor_mode::draw_track_legend() const
 {
 	if (m_track_colouring == track_colouring::plain)

lang/editor_pl.po

@@ -10123,3 +10123,9 @@ msgstr "Według pochylenia"
 
 msgid "The tracks of the track mode coloured by their radius, speed or grade, with the legend in the corner"
 msgstr "Tory w dziale Tory pokolorowane według promienia, prędkości albo pochylenia, z legendą w rogu"
+
+msgid "Track labels in the top view"
+msgstr "Opisy torów w widoku z góry"
+
+msgid "Zoomed in from above, the curves get their radius and length and the switches their name and type, as on a plan; where they'd crowd, some are left out"
+msgstr "Po przybliżeniu z góry łuki dostają promień i długość, a rozjazdy nazwę i typ, jak na planie; gdzie byłoby ich za gęsto, część się chowa"