Switch pathfinder refresh to timestamp-based interval (#11482)

core/src/mindustry/ai/Pathfinder.java

@@ -106,6 +106,10 @@ public class Pathfinder implements Runnable{
     IntSeq tmpArray = new IntSeq();
 
     boolean needsRefresh;
+    /** Last time flowfields were refreshed, for timestamp-based refresh interval. */
+    private long lastRefreshTime;
+    /** Minimum interval between flowfield refreshes in milliseconds. */
+    private static final long refreshIntervalMs = 100;
 
     public Pathfinder(){
         clearCache();
@@ -182,9 +186,12 @@ public class Pathfinder implements Runnable{
         });
 
         Events.run(Trigger.afterGameUpdate, () -> {
-            //only refresh periodically (every 2 frames) to batch flowfield updates
-            //TODO: is it worth switching to a timestamp based system instead that updates every X milliseconds?
-            if(needsRefresh && Core.graphics.getFrameId() % 2 == 0){
+            if(!needsRefresh) return;
+
+            long now = Time.millis();
+            if(now - lastRefreshTime < refreshIntervalMs) return;
+
+            lastRefreshTime = now;
             needsRefresh = false;
 
             //can't iterate through array so use the map, which should not lead to problems
@@ -204,7 +211,6 @@ public class Pathfinder implements Runnable{
                     data.dirty = true;
                 }
             });
-            }
         });
     }