Obstacles

Purpose

To make the game become more challenging and immerse the player into the atmosphere of the game, we aim to implement the obstacle feature for the game. Initially, once the player starts the game, several types of obstacles will appear on the game map. In addition, different types of obstacles will cause different amounts of damage to the game character, and also they will have different movements and functionalities. In order to survive the game, the player must try to avoid as many obstacles as possible.

Types of obstacles

Static obstacles:

• Asteroid: A type of static obstacle that appears once the game starts and the position of each asteroid remains stable within the game. It does not have any damage to the player but the player cannot pass it directly.
• Asteroid fire: A type of static obstacle that appears once the game starts and the position of each asteroid fire remains stable within the game. For those asteroid fire obstacles on the map, if the player touches them (inside of the attack range of the asteroid fire), the player's health will be reduced by 10.
• Platform: A type of static obstacle that appears once the game starts and the position of each platform remains stable within the game. For those platform obstacles on the map, the player could jump onto them and move freely. This obstacle would not cause any damage to the player. Therefore, the player could use them effectively to avoid other types of obstacles.
• Portal: A static obstacle that appears at the end of every map. Once the player collides with this they will be shown the win screen and prompted to go to the next level. This was implemented so it made more sense how players were travelling between levels.
• Rocks: When the game starts, rocks are randomly distributed on the horizontal surface, and the types of rocks will also change randomly. Rocks will block the player's walking, but the player can jump over the rocks, and the rocks cannot cause damage.(Not adopted)
• Buildings: The building does not affect the player in any way, it is part of the background.(Not adopted)

Kinematic obstacle:

• HorizontalMovingPlatform: A type of Kinematic obstacle that appears once the game starts. The platform moves horizontally (left to right) at a constant speed. Players can stand on a moving platform and follow the platform to move. The moving platform could increase the difficulty of the game and the player must consider the time to jump onto it.
• VerticalMovingPlatform: A type of Kinematic obstacle that appears once the game starts. The platform moves vertically (top to bottom) at a constant speed. Players can stand on a moving platform and follow the platform to move. The moving platform could increase the difficulty of the game and the player must consider the time to jump onto it.

Dynamic obstacles:

• UFO: A type of dynamic obstacle that randomly appears in the upper area of the map When the game is running, and randomly moves in different directions during the game. When the player collides with the UFO, the player will lose a certain amount of blood that is 25.
• Robot: A type of dynamic obstacle that appears once the game starts and the position of the robot should be constantly changing. During the game, the robot will move left and right at a constant speed. For the robot on the map, if the player collides with it(inside of the attack range of the robot), the player's health will be reduced by 20.

Implementation

Key Components

• obstacle.json This JSON file includes the initial properties (health, baseAttack) of all the aggressive obstacles.
• ObstacleConfig Defines all Obstacle configs to be loaded by the Obstacle Factory.
• AsteroidConfig RobotConfig UfoConfig Defines the properties stored in obstacle config files to be loaded by the Obstacle Factory.
• ObstacleFactory Factory to create obstacle entities, all types of obstacles are created and implemented here, including createAsteroid(), createAsteroidFire(), createRobot(), createUfo(), createPlatform1(), createPlatform3().
• ForestGameArea Area for initializing game entities, including all the obstacles. spawnAsteriod(), spawnAsteroidFire(), spawnRobot(), spawnUFO(), spawnPlatform1() and spawnPortal() are implemented here.
• PlatformTask Set a task for the platform to move it left and right.

Code of creating Static Obstacles

  public static Entity createAsteroid() {
    Entity asteroid =
            new Entity()
                    .addComponent(new TextureRenderComponent("images/broken_asteriod.png"))
                    .addComponent(new PhysicsComponent())
                    .addComponent(new ColliderComponent().setLayer(PhysicsLayer.OBSTACLE));

    asteroid.getComponent(PhysicsComponent.class).setBodyType(BodyType.StaticBody);
    asteroid.getComponent(TextureRenderComponent.class).scaleEntity();
    asteroid.scaleHeight(0.7f);
    PhysicsUtils.setScaledCollider(asteroid, 0.7f, 0.5f);
    return asteroid;
  }

Code of creating Dynamic Obstacles

  public static Entity createRobot(Entity target) {
    RobotConfig config = configs.robot;
    AITaskComponent aiComponent =
            new AITaskComponent()
                    .addTask(new WanderTask(new Vector2(10f, 0f), 0f));
    Entity robot =
            new Entity()
                    .addComponent(new PhysicsComponent())
                    .addComponent(new PhysicsMovementComponent())
                    .addComponent(new ColliderComponent().setLayer(PhysicsLayer.OBSTACLE))
                    .addComponent(new HitboxComponent().setLayer(PhysicsLayer.NPC))
                    .addComponent(new TouchAttackComponent(PhysicsLayer.PLAYER, 0f))
                    .addComponent(new TextureRenderComponent("images/robot1.png"))
                    .addComponent(new CombatStatsComponent(config.health, config.baseAttack))
                    .addComponent(aiComponent);
    robot.getComponent(PhysicsComponent.class).setBodyType(BodyType.DynamicBody);

    return robot;
  }

Set the properties of Obstacle

You can initialize and change the properties of the obstacle here obstacle.json

{
  "asteroidFire": {
    "health": 100,
    "baseAttack": 10
  },
  "robot": {
    "health": 100,
    "baseAttack": 20
  },
  "ufo": {
    "health": 100,
    "baseAttack": 25
  }
}

Add the obstacle to forest game area

You can add the obstacle to forest game area here and modify the position of obstacles.

  private void spawnRobot() {
    GridPoint2 pos1 = new GridPoint2(12, 16);
    Entity robot1 = ObstacleFactory.createRobot(player);
    spawnEntityAt(robot1, pos1, true, true);
  }

Then, you can initialise the obstacles inside create()

  public void create() {

    spawnAsteriod();
    spawnAsteroidFire();
    spawnRobot();
    spawnPlatform1();
    spawnUFO();

  }

Add the obstacle at random locations to forest game area

Obstacles will randomly appear at different positions on the horizontal line of the map

  private void spawnBuilding() {
    GridPoint2 minPos = new GridPoint2(2, 10);
    GridPoint2 maxPos = terrain.getMapBounds(0).sub(2, 20);
    for (int i = 0; i < NUM_BUILDINGS; i++) {
      GridPoint2 randomPos = RandomUtils.random(minPos, maxPos);
      Entity building = ObstacleFactory.createBuilding1();
      spawnEntityAt(building, randomPos, true, false);
    }
  }

Add four different types of rocks and make them appear randomly

  private void spawnRocks() {
    GridPoint2 minPos = new GridPoint2(5, 10);
    GridPoint2 maxPos = terrain.getMapBounds(0).sub(2, 20);
    Random r = new Random();

    for (int i = 0; i < NUM_ROCKS; i++) {
      GridPoint2 randomPos = RandomUtils.random(minPos, maxPos);
      Entity rock1 = ObstacleFactory.createRock1();
      Entity rock2 = ObstacleFactory.createRock2();
      Entity rock3 = ObstacleFactory.createRock3();
      Entity rock4 = ObstacleFactory.createRock4();

      if(r.nextInt(4) == 0) {
        spawnEntityAt(rock1, randomPos, true, false);
      } else if(r.nextInt(4) == 1) {
        spawnEntityAt(rock2, randomPos, true, false);
      } else if(r.nextInt(4) == 2) {
        spawnEntityAt(rock3, randomPos, true, false);
      } else {
        spawnEntityAt(rock4, randomPos, true, false);
      }
    }

Create a moving Task for Platform

The method of creating a moving platform is similar to the method of creating a stationary platform, we only need to add PlatformTask to it when creating a moving platform and change its setBodyType to BodyType.KinematicBody.

public class PlatformTask extends DefaultTask implements PriorityTask {
    private final int priority;
    private final float x;
    private float p_x = 0;
    private boolean isMove = true;

    /**
     * @param priority Task priority when chasing (0 when not chasing).
     */
    public PlatformTask(float x, int priority) {
        this.x = x;
        this.priority = priority;
    }

    @Override
    public void start() {
        super.start();
        p_x = this.owner.getEntity().getPosition().x;
    }

    @Override
    public void update() {
        float position_x = this.owner.getEntity().getPosition().x;
        if (isMove) {
            if(position_x <= p_x + x/2) {
                this.owner.getEntity().getComponent(PhysicsComponent.class).getBody().setLinearVelocity(new Vector2(1,0));
            } else {
                isMove = false;
            }
        } else {
            if(position_x >= p_x - x/2) {
                this.owner.getEntity().getComponent(PhysicsComponent.class).getBody().setLinearVelocity(new Vector2(-1,0));
            } else {
                isMove = true;
            }
        }
    }

    @Override
    public void stop() {
        super.stop();
    }

    @Override
    public int getPriority() {
        return priority;
    }
}

Forest game area after adding the obstacles

UML