feat(editor): the terrain of a scenery begun from nothing grows where the track is laid

The terrain model was made once around the camera when a new scenery
took it; tracks laid on past it went over nothing. While a track is laid
or dragged out, the chunks missing within 400 m of the cursor are now
made from the model too, the nearest first, in a scenery with the
heightmap terrain placed on the map. The formations aren't made anew
after such chunks. A chip in the terrain panel turns it off.

application/editormode.h

@@ -345,6 +345,9 @@ class editor_mode : public application_mode, private editor_track::observer
 		std::size_t samples{0};
 		double band{300.0}; // m from the tracks the chunks made along them reach
 		bool shape{true}; // the formation and the slopes of the tracks as modifiers of the terrain
+		bool grow{true}; // while a track is laid, the terrain is made around the cursor where there's none
+		bool grown{false}; // the chunks waiting were all asked for by growing: the formations aren't made anew after them
+		double grow_time{-10.0};
 		double slope{1.5};
 		double reach{60.0};
 		std::vector<heightmap::chunk_key> pending; // chunks to make once their model is in
@@ -406,6 +409,7 @@ class editor_mode : public application_mode, private editor_track::observer
 	// of the modifiers laid
 	std::size_t nmt_shape_tracks(std::vector<TTrack *> const *Only = nullptr);
 	void nmt_update();
+	void nmt_grow();
 	void render_nmt_ui();
 	// a scenery begun from nothing, with no tracks nor terrain, is asked as the first track is laid whether it wants the terrain
 	void nmt_offer();

application/editormodenmt.cpp

@@ -452,6 +452,8 @@ void editor_mode::nmt_make(std::vector<heightmap::chunk_key> const &Keys, bool c
 			++queued;
 		}
 	state.made = 0;
+	if (queued > 0)
+		state.grown = false;
 	// the terrain comes with its photos
 	if (queued > 0 && false == m_orthophoto.enabled())
 		m_orthophoto.enabled(true);
@@ -597,6 +599,7 @@ void editor_mode::nmt_update()
 			nmt_finish_fit();
 		return;
 	}
+	nmt_grow();
 	if (state.pending.empty())
 		return;
 	// a few chunks a frame, those whose model is in
@@ -623,7 +626,7 @@ void editor_mode::nmt_update()
 		state.status = format(STR_C("Chunks made from the terrain model: %zu, waiting for it: %zu"), state.made, state.pending.size());
 		if (state.pending.empty())
 		{
-			if (state.shape)
+			if (state.shape && false == state.grown)
 			{
 				nmt_shape_tracks();
 				state.status += format(STR_P("; the formation of %zu path shaped", "; the formation of %zu paths shaped", state.shaped), state.shaped);
@@ -637,6 +640,44 @@ void editor_mode::nmt_update()
 		state.error = STR(error);
 }
 
+void editor_mode::nmt_grow()
+{
+	auto &state{m_nmt_state};
+	auto const now{ImGui::GetTime()};
+	if (false == state.grow || now - state.grow_time < 0.5 || (false == m_lay.active && false == m_extend.active) || m_streamer.resident() == 0 || false == m_nmt.placed())
+		return;
+	state.grow_time = now;
+	auto const at{m_extend.active ? m_extend.mouse : m_lay.mouse};
+	glm::dvec2 const cursor{at.x, at.z};
+	double constexpr grow_reach{400.0}; // m around the cursor
+	auto const reach{static_cast<int>(std::ceil(grow_reach / heightmap::chunk_size))};
+	auto const centre{heightmap::chunk_at(at.x, at.z)};
+	std::vector<std::pair<double, heightmap::chunk_key>> missing;
+	for (int dz = -reach; dz <= reach; ++dz)
+		for (int dx = -reach; dx <= reach; ++dx)
+		{
+			heightmap::chunk_key const key{centre.first + dx, centre.second + dz};
+			auto const low{heightmap::chunk_corner(key)};
+			glm::dvec2 const nearest{std::clamp(cursor.x, low.x, low.x + heightmap::chunk_size), std::clamp(cursor.y, low.y, low.y + heightmap::chunk_size)};
+			auto const distance{glm::distance(nearest, cursor)};
+			if (distance <= grow_reach && false == m_streamer.exists(key) && std::find(state.pending.begin(), state.pending.end(), key) == state.pending.end())
+				missing.emplace_back(distance, key);
+		}
+	if (missing.empty())
+		return;
+	std::sort(missing.begin(), missing.end());
+	if (state.pending.empty())
+	{
+		state.grown = true;
+		state.made = 0;
+	}
+	for (auto const &chunk : missing)
+		state.pending.push_back(chunk.second);
+	if (false == m_orthophoto.enabled())
+		m_orthophoto.enabled(true);
+	WriteLog(format("Editor: NMT - %zu chunks around the cursor to make", missing.size()), logtype::generic);
+}
+
 void editor_mode::render_nmt_ui()
 {
 	auto &state{m_nmt_state};
@@ -748,6 +789,7 @@ void editor_mode::render_nmt_ui()
 		                           STR_C("Loads the terrain model, the real relief of the ground, around the camera")};
 		ImGui::SetTooltip("%s\n%s", text, STR_C("Terrain model: GUGiK, geoportal.gov.pl"));
 	}
+	toggle_chips("nmtgrow", {{STR_C("Make the terrain ahead while laying"), &state.grow, "Where a track is laid past the edge of the terrain, the terrain model is made around the cursor as it goes"}});
 	// how far it got
 	if (state.stage == nmt_state::automatic::fetching || state.fitting)
 	{

lang/editor_pl.po

@@ -9943,3 +9943,9 @@ msgstr "równolegle do %s"
 
 msgid "%.0f deg to %s"
 msgstr "%.0f° do %s"
+
+msgid "Make the terrain ahead while laying"
+msgstr "Dobudowuj teren przy układaniu"
+
+msgid "Where a track is laid past the edge of the terrain, the terrain model is made around the cursor as it goes"
+msgstr "Gdy tor wychodzi poza teren, NMT dobudowuje się wokół kursora na bieżąco"