2.4 Enemy design

Design

Objectives

Set up the enemy

• code the funtion to make the enemy walk left and right

• And swap direcions when colliding with a wall

• Adding collison so when the player and the enemy colides (on top) the enemy dies

Usability Features

Key Variables

Variable Name	Use
patrol	Sets the constant downward acceleration
onCollide	Show the anchor point of the Sprite
Load Sprite	Used to input what each symbol represents in the level
Area	Collision detection (T/F)
Body	Static properties (T/F)
dir	Direction of movement

Pseudocode

Function patrol(speed = 60, dir = 1):
    Return an object with the following properties and behaviors:
    id: "patrol"
    require: ["pos", "area"]
    add():
        When an object with this behavior is added to the game:
        Set up an event listener for "collide"
        When a collision occurs:
        If the collision is on the left or right side of the object:
        Change the direction of patrol to the opposite direction

    update():
        On each game update:
        Move the object in the horizontal direction at a speed of "speed" multiplied by "dir"

"*" (For all objects with this behavior):
    Create a sprite with the image "bad guy"
    Define an area for the object
    Add a physics body to the object
    Add the "patrol" behavior to the object
    Set the anchor point of the object to the bottom
    Assign the label "enemy" to the object


  
  

Development

Outcome

 function patrol(speed = 60, dir = 1) {
  return {
    id: "patrol",
    require: ["pos", "area"],
    add() {
      this.on("collide", (obj, col) => {
        if (col.isLeft() || col.isRight()) {
          dir = -dir;
        }
      });
    },
    update() {
      this.move(speed * dir, 0);
    },
  };
}


//

      "*": () => [
        sprite("bad guy"),
        area(),
        body(),
        patrol(),
        anchor("bot"),
        "enemy",
        
        
         
    // Handle player collision with enemies
    player.onCollide("enemy", (enemy, col) => {
        if (col.isBottom()) {
            // Kill the enemy when collision is from the top
            destroy(enemy);
        } else {
            // Player collided with the enemy from the side or below, go to the "lose" scene
            go("lose");
        }
    });

                
//
        

Challenges

setting a speed value that makes platforming smooth and movement feel responsive

Testing

Evidence for testing

Tests

Test	Instructions	What I expect	What actually happens	Pass/Fail
1	Player colliedes with the enemy (on top)	The enemy to be destroyed	The enemy is destroyed	Pass
2	Player colliedes with the enemy (anywhere else)	The player to be destroyed	The player is destroyed	Pass

Evidence