ai: Discourage from fleeing to arena borders

src/core/ai/Maneuver.ts

@@ -38,5 +38,16 @@ module TS.SpaceTac {
                 });
             }
         }
+
+        /**
+         * Get the location of the ship after the action
+         */
+        getFinalLocation(): { x: number, y: number } {
+            if (this.simulation.need_move) {
+                return this.simulation.move_location;
+            } else {
+                return { x: this.ship.arena_x, y: this.ship.arena_y };
+            }
+        }
     }
 }

src/core/ai/TacticalAI.ts

@@ -104,6 +104,7 @@ module TS.SpaceTac {
                 scaled(TacticalAIHelpers.evaluateTurnCost, 1),
                 scaled(TacticalAIHelpers.evaluateDamageToEnemy, 30),
                 scaled(TacticalAIHelpers.evaluateClustering, 3),
+                scaled(TacticalAIHelpers.evaluatePosition, 1),
             ]
             // TODO evaluator typing is lost
             evaluators.forEach(evaluator => this.evaluators.push((maneuver: Maneuver) => evaluator(this.ship, this.ship.getBattle(), maneuver)));

src/core/ai/TacticalAIHelpers.spec.ts

@@ -141,5 +141,27 @@ module TS.SpaceTac.Specs {
             battle.fleets[0].addShip().setArenaPosition(110, 20);
             expect(TacticalAIHelpers.evaluateClustering(ship, battle, maneuver)).toEqual(-1);
         });
+
+        it("evaluates ship position", function () {
+            let battle = new Battle(undefined, undefined, 200, 100);
+            let ship = battle.fleets[0].addShip();
+            let weapon = TestTools.addWeapon(ship, 1, 1, 400);
+
+            ship.setArenaPosition(0, 0);
+            let maneuver = new Maneuver(ship, weapon, new Target(0, 0), 0);
+            expect(TacticalAIHelpers.evaluatePosition(ship, battle, maneuver)).toEqual(-1);
+
+            ship.setArenaPosition(100, 0);
+            maneuver = new Maneuver(ship, weapon, new Target(0, 0), 0);
+            expect(TacticalAIHelpers.evaluatePosition(ship, battle, maneuver)).toEqual(-1);
+
+            ship.setArenaPosition(100, 10);
+            maneuver = new Maneuver(ship, weapon, new Target(0, 0), 0);
+            expect(TacticalAIHelpers.evaluatePosition(ship, battle, maneuver)).toEqual(-0.6);
+
+            ship.setArenaPosition(100, 50);
+            maneuver = new Maneuver(ship, weapon, new Target(0, 0), 0);
+            expect(TacticalAIHelpers.evaluatePosition(ship, battle, maneuver)).toEqual(1);
+        });
     });
 }

src/core/ai/TacticalAIHelpers.ts

@@ -95,7 +95,7 @@ module TS.SpaceTac {
          */
         static evaluateClustering(ship: Ship, battle: Battle, maneuver: Maneuver): number {
             // TODO Take into account blast radius of in-play weapons
-            let move_location = maneuver.simulation.move_location || Target.newFromShip(ship);
+            let move_location = maneuver.getFinalLocation();
             let distances = imaterialize(imap(ifilter(battle.iships(), iship => iship != ship), iship => Target.newFromShip(iship).getDistanceTo(move_location)));
             if (distances.length == 0) {
                 return 0;
@@ -106,5 +106,15 @@ module TS.SpaceTac {
                 return result;
             }
         }
+
+        /**
+         * Evaluate the global positioning of a ship on the arena, between -1 and 1
+         */
+        static evaluatePosition(ship: Ship, battle: Battle, maneuver: Maneuver): number {
+            let pos = maneuver.getFinalLocation();
+            let distance = min([pos.x, pos.y, battle.width - pos.x, battle.height - pos.y]);
+            let factor = min([battle.width / 2, battle.height / 2]);
+            return -1 + 2 * distance / factor;
+        }
     }
 }