"Reduce observation vector size and refocus AI on key game metrics"

Reduced the VectorObservationSize in Prefabs/SnakeAgent.prefab from 71 to 5. This change fine-tunes the AI's attention towards the most important information for decision-making in the game. The Observation Vector will now only include data on the direction to the food and immediate dangers for the snake - front, left, and right positions relative to the snake's heading. This will help in optimising the performance of the AI.

Also adapted AI_timers.json and SnakeAgent.cs files to reflect these changes.

Assets/ML-Agents/Timers/AI_timers.json

@@ -1 +1 @@
-{"count":1,"self":40.0425568,"total":40.238061599999995,"children":{"InitializeActuators":{"count":16,"self":0.0020276,"total":0.0020276,"children":null},"InitializeSensors":{"count":16,"self":0.0005068,"total":0.0005068,"children":null},"AgentSendState":{"count":60,"self":0.0030371,"total":0.070967099999999991,"children":{"CollectObservations":{"count":480,"self":0.0035174,"total":0.0035174,"children":null},"WriteActionMask":{"count":480,"self":0,"total":0,"children":null},"RequestDecision":{"count":480,"self":0.0644126,"total":0.0644126,"children":null}}},"DecideAction":{"count":60,"self":0.045922,"total":0.045922,"children":null},"AgentAct":{"count":60,"self":0.076081799999999991,"total":0.076081799999999991,"children":null}},"gauges":{"SnakeAi.CumulativeReward":{"count":106,"max":-0.003001213,"min":-10.008,"runningAverage":-9.815557,"value":-10.005,"weightedAverage":-10.0048523}},"metadata":{"timer_format_version":"0.1.0","start_time_seconds":"1689087858","unity_version":"2023.1.3f1","command_line_arguments":"C:\\Program Files\\Unity\\Hub\\Editor\\2023.1.3f1\\Editor\\Unity.exe -projectpath C:\\Users\\felix\\SnakeGame -useHub -hubIPC -cloudEnvironment production","communication_protocol_version":"1.5.0","com.unity.ml-agents_version":"2.3.0-exp.3","scene_name":"AI","end_time_seconds":"1689087899"}}
+{"count":1,"self":312.13376,"total":578.49973879999993,"children":{"InitializeActuators":{"count":16,"self":0.0010077999999999999,"total":0.0010077999999999999,"children":null},"InitializeSensors":{"count":16,"self":0,"total":0,"children":null},"AgentSendState":{"count":31843,"self":0.5999386,"total":2.4476492999999997,"children":{"CollectObservations":{"count":238033,"self":0.3295816,"total":0.3295816,"children":null},"WriteActionMask":{"count":238033,"self":0.11404349999999999,"total":0.11404349999999999,"children":null},"RequestDecision":{"count":238033,"self":0.3964431,"total":1.4040856,"children":{"AgentInfo.ToProto":{"count":237905,"self":0.37333649999999996,"total":1.0076425,"children":{"GenerateSensorData":{"count":237905,"self":0.63430599999999993,"total":0.63430599999999993,"children":null}}}}}}},"DecideAction":{"count":31843,"self":255.17744639999998,"total":255.1774481,"children":null},"AgentAct":{"count":31843,"self":8.7121871999999989,"total":8.739863999999999,"children":{"AgentInfo.ToProto":{"count":4018,"self":0.0145954,"total":0.027676899999999997,"children":{"GenerateSensorData":{"count":4018,"self":0.0130815,"total":0.0130815,"children":null}}}}}},"gauges":{"SnakeAi.CumulativeReward":{"count":4042,"max":109.316093,"min":-10.4399977,"runningAverage":-2.30997682,"value":39.7010956,"weightedAverage":48.6735573}},"metadata":{"timer_format_version":"0.1.0","start_time_seconds":"1689089519","unity_version":"2023.1.3f1","command_line_arguments":"C:\\Program Files\\Unity\\Hub\\Editor\\2023.1.3f1\\Editor\\Unity.exe -projectpath C:\\Users\\felix\\SnakeGame -useHub -hubIPC -cloudEnvironment production","communication_protocol_version":"1.5.0","com.unity.ml-agents_version":"2.3.0-exp.3","scene_name":"AI","end_time_seconds":"1689090097"}}

Assets/SnakeGame/Prefabs/SnakeAgent.prefab

@@ -78,7 +78,7 @@ MonoBehaviour:
   m_Name: 
   m_EditorClassIdentifier: 
   m_BrainParameters:
-    VectorObservationSize: 71
+    VectorObservationSize: 5
     NumStackedVectorObservations: 1
     m_ActionSpec:
       m_NumContinuousActions: 0

Assets/SnakeGame/Scripts/SnakeAgent.cs

@@ -2,6 +2,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using TMPro;
 using Unity.MLAgents;
 using Unity.MLAgents.Actuators;
@@ -125,27 +126,49 @@ private static bool IsSnakeAlive(Snake snake) {
 
 
         public override void CollectObservations(VectorSensor sensor) {
-            if (board.Snakes.Length > 0) {
-                sensor.AddObservation(board.Snakes[0].Direction);
-                sensor.AddObservation(board.Snakes[0].Position);
-                sensor.AddObservation(PreviousDistance);
-                sensor.AddObservation(board.FoodPositions[0]);
-                int[] array = board.GetBoardAsArray();
-
-                for (int i = 0; i < array.Length; i++) {
-                    sensor.AddObservation(array[i]);
-                }
-            } else {
-                sensor.AddObservation(Vector2.zero);
-                sensor.AddObservation(Vector2.zero);
-                sensor.AddObservation(Vector2.zero);
+            // Assuming that there is always at least one snake and one food in the game
+            var snake = board.Snakes[0];
+            var food = board.FoodPositions[0];
+
+            // Calculate direction to the food relative to the snake's heading
+            Vector2 directionToFood = (food - snake.Position);
+            // Normalize directionToFood
+            directionToFood = directionToFood.normalized;
+
 
-                int[] array = board.GetBoardAsArray();
+                    // Add the direction to the food (2 floats)
+                    sensor.AddObservation(directionToFood);
 
-                for (int i = 0; i < array.Length; i++) {
-                    sensor.AddObservation(-1);
+            // Check for immediate dangers: front, left, right relative to the snake's current direction
+            var forwardPosition = snake.Position + snake.Direction;
+            var leftPosition = snake.Position + RotateCounterClockwise(snake.Direction);
+            var rightPosition = snake.Position + RotateClockwise(snake.Direction);
+
+            // Check if next positions are inside the board and not occupied by the snake's body
+            sensor.AddObservation(IsPositionSafe(forwardPosition));
+            sensor.AddObservation(IsPositionSafe(leftPosition));
+            sensor.AddObservation(IsPositionSafe(rightPosition));
+        }
+
+        private bool IsPositionSafe(Vector2Int position) {
+            // Define the condition for the position to be safe. The following is just a basic example.
+            // You might need to add more conditions or modify it according to your game rules.
+
+            // Check if out of bounds
+            if (position.x < 0 || position.y < 0 || position.x >= width || position.y >= height)
+                return false;
+
+            // Check if would collide with the snake
+            foreach (var snake in board.Snakes)
+            {
+                if (snake.Body.Contains(position)) {
+
+                    return false;
                 }
             }
+
+            // If passed both conditions, the position is safe.
+            return true;
         }
 
         private Vector2Int RotateClockwise(Vector2Int direction) {