added routing logic and network graph improvements

@miSim/plotGraph.m

@@ -6,8 +6,7 @@ function obj = plotGraph(obj)
         obj (1, 1) {mustBeA(obj, "miSim")};
     end
 
-    % Form graph from adjacency matrix
-    G = graph(obj.constraintAdjacencyMatrix, "omitselfloops");
+    nAgents = size(obj.agents, 1);
 
     % Resolve the target axes for the network graph tile
     if isnan(obj.networkGraphIndex)
@@ -16,7 +15,36 @@ function obj = plotGraph(obj)
         ax = obj.f.Children(1).Children(obj.networkGraphIndex(1));
     end
 
-    % Plot graph object
+    % Build the graph to plot. The fixed-radius model is undirected. In SINR
+    % mode the link set (lesser-neighbor topology) is kept exactly as-is, but
+    % each connection is given an orientation: of the two directional SINRs on
+    % a link, the larger one wins, and the edge is directed from that
+    % direction's transmitter to its receiver (arrow = transmitter -> receiver).
+    if obj.useSinrComms
+        positions = zeros(nAgents, 3);
+        for kk = 1:nAgents
+            positions(kk, :) = obj.agents{kk}.pos;
+        end
+        D = false(nAgents);   % directed adjacency: D(tx, rx) = true
+        for aa = 1:(nAgents - 1)
+            for bb = (aa + 1):nAgents
+                if obj.constraintAdjacencyMatrix(aa, bb)
+                    sinrARx = obj.sinrLink(positions, aa, bb); % aa receives bb
+                    sinrBRx = obj.sinrLink(positions, bb, aa); % bb receives aa
+                    if sinrARx >= sinrBRx
+                        D(bb, aa) = true;  % better as bb -> aa (tx bb, rx aa)
+                    else
+                        D(aa, bb) = true;  % better as aa -> bb (tx aa, rx bb)
+                    end
+                end
+            end
+        end
+        G = digraph(D);
+    else
+        G = graph(obj.constraintAdjacencyMatrix, "omitselfloops");
+    end
+
+    % Plot graph object (digraph renders arrowheads automatically)
     hold(ax, "on");
     o = plot(ax, G, "LineStyle", "--", "EdgeColor", "g", "NodeColor", "k", "LineWidth", 2);
     hold(ax, "off");
@@ -26,34 +54,33 @@ function obj = plotGraph(obj)
         end
     end
 
-    % In SINR comms mode, label each edge with the connection's SINR and report
-    % the connectivity threshold in the tile title. The fixed-radius model is
-    % left unchanged (no edge labels, title stays as set in firstPlotSetup).
+    % Mark ground-station-connected nodes with an "x" (others keep the default
+    % dot). Ground stations attach to the two "router" agents: agent 1 and the
+    % agent with the largest ODD index (that is nAgents when odd, else
+    % nAgents-1). With one or two agents only agent 1 qualifies.
+    routers = unique([1, 2 * ceil(nAgents / 2) - 1]);
+    for oo = 1:numel(o)
+        highlight(o(oo), routers, "Marker", "x", "MarkerSize", 8);
+    end
+
+    % In SINR comms mode, label each directed edge with the better SINR that set
+    % its orientation and report the threshold in the tile title. The
+    % fixed-radius model is left unchanged (no edge labels, title from setup).
     if obj.useSinrComms
-        endNodes = G.Edges.EndNodes;   % each row [lo hi]; graph stores lo < hi
-        nAgents = size(obj.agents, 1);
-        positions = zeros(nAgents, 3);
-        for kk = 1:nAgents
-            positions(kk, :) = obj.agents{kk}.pos;
-        end
-        % A link is feasible only if BOTH directions clear the threshold, so
-        % label each edge with the binding (worse) directional SINR: the min of
-        % the lower-index-receiver and higher-index-receiver links, with
-        % interference from all other agents at each receiver. Labels are bare
-        % numbers (no units) so they stay compact; GraphPlot renders them
+        endNodes = G.Edges.EndNodes;   % each row [tx rx] for a directed edge
+        % Label with the SINR of the chosen (better) direction: the receiver is
+        % the edge target, the transmitter the edge source. Bare numbers (no
+        % units) keep the small tile uncluttered; GraphPlot draws labels
         % horizontally, left-to-right.
         edgeLabels = strings(size(endNodes, 1), 1);
         for ee = 1:size(endNodes, 1)
-            lo = endNodes(ee, 1);
-            hi = endNodes(ee, 2);
-            sinrLoRx = obj.sinrLink(positions, lo, hi); % receiver lo (lower index)
-            sinrHiRx = obj.sinrLink(positions, hi, lo); % receiver hi (higher index)
-            edgeLabels(ee) = sprintf("%.1f", 10 * log10(min(sinrLoRx, sinrHiRx)));
+            sinrLin = obj.sinrLink(positions, endNodes(ee, 2), endNodes(ee, 1)); % rx, tx
+            edgeLabels(ee) = sprintf("%.1f", 10 * log10(sinrLin));
         end
         o(1).EdgeLabel = edgeLabels;
-        % Threshold goes in the existing single-line title (not a subtitle) so
-        % the small tile is not compressed further, and the hover toolbar is
-        % disabled so the R2026 "..." menu stops covering the readout.
+        % Threshold in the existing single-line title (not a subtitle) so the
+        % small tile isn't compressed, and disable the hover toolbar so the
+        % R2026 "..." menu stops covering the readout.
         title(ax, sprintf("Network Graph (\\geq %.1f dB)", obj.sinrThreshold));
         ax.Toolbar.Visible = "off";
     end