fix(editor): the orthophoto which comes before the terrain under it lies where the terrain will be, at the heights of the terrain model with the offset of the scenery, or level with the tiles beside along its edges, not flat at the height of the layer far below; the squares of the model asked for, and the tile laid onto the terrain or the model once either comes

mapstate logs how many tiles lie on the ground and how many at guessed heights.

application/editormode.cpp

@@ -558,6 +558,21 @@ editor_mode::editor_mode() {
 		gather_ground_triangles(Min, Max, true, 50.0f, Out, true, Heightmap);
 	});
 	m_orthophoto.height_source([](double const X, double const Z, double &Height) { return EditorTerrain.height_at(X, Z, Height); });
+	// the imagery often comes before the terrain made from the model: it lies where the terrain will be
+	m_orthophoto.guess_source([this](double const X, double const Z, double &Height) {
+		if (nmt_ahead(X, Z, Height))
+			return true;
+		if (false == m_nmt.placed())
+			return false;
+		if (false == m_nmt.height(X, Z, Height))
+		{
+			// asked for, the tile goes onto it once it comes
+			m_nmt.request({X - 1.0, Z - 1.0}, {X + 1.0, Z + 1.0});
+			return false;
+		}
+		Height += nmt_offset_at(X, Z);
+		return true;
+	});
 	editor_track::observe(this);
  }
 
@@ -1481,6 +1496,14 @@ bool editor_mode::update()
         Global.EditorOrthoMap = m_orthophoto.enabled() && metres >= (m_orthophoto.overview() ? 1.6 : 2.0);
         m_orthophoto.overview(Global.EditorOrthoMap ? metres : 0.0, static_cast<double>(Global.EditorOrthoExtent) * std::sqrt(1.0 + aspect * aspect));
     }
+    // chunks of the terrain come from the files and from the model: the imagery lying at guessed heights goes onto them
+    // and so do the squares of the model it lies on meanwhile
+    auto const resident{m_streamer.resident()};
+    auto const waiting{m_nmt.waiting()};
+    if (resident > m_ortho_resident || waiting < m_ortho_waiting)
+        m_orthophoto.ground_arrived();
+    m_ortho_resident = resident;
+    m_ortho_waiting = waiting;
     m_orthophoto.update(Camera.Pos);
     nmt_update();
     draw_orthophoto();