2.5 Boss design

Design

Objectives

• Set up a final bass

• Program the bos with ai to periodily chase and then flee the player

Usability Features

Key Variables

Variable Name	Use
chaseAndFlee	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 chaseAndFlee(speed = 60):
    Initialize dir as 1
    Initialize chasing as true
    
    Return an object with the following properties and behaviors:
    id: "chaseAndFlee"
    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:
        If chasing is true:
            Calculate the distance between the boss and player
            Get the first player object in the game
            Calculate the distanceToPlayer as the difference in x-position between the boss and the player
            If player exists and the distanceToPlayer is greater than 1000:
                Set dir based on the sign of the distanceToPlayer
                Move the object horizontally by speed multiplied by dir
            Else:
                Set chasing to false
        Else:
            Move the object horizontally by speed multiplied by dir
    
"*" (For all objects with this behavior):
    Create a sprite with the image "Boss"
    Define an area for the object
    Add a physics body to the object
    Add the "chaseAndFlee" behavior to the object
    Set the anchor point of the object to the bottom
    Scale the object by a factor of 3
    Assign the label "Boss" to the object



  
  

Development

Outcome

function chaseAndFlee(speed = 60) {
    let dir = 1;
    let chasing = true;

    return {
        id: "chaseAndFlee",
        require: ["pos", "area"],
        add() {
            this.on("collide", (obj, col) => {
                if (col.isLeft() || col.isRight()) {
                    dir = -dir;
                }
            });
        },
        update() {
            if (chasing) {
                // Calculate the distance between boss and player
                const player = get("player")[0];
                var distanceToPlayer = player ? player.pos.x - this.pos.x :Infinity

                // If the player is within a certain range, chase the player
                if (distanceToPlayer > 1000) {
                    dir = Math.sign(distanceToPlayer); // Set direction based on player position
                    this.move(speed * dir, 0);
                } else {
                    chasing = false;
                }
            } else {
                // Flee from the player
                this.move(speed * dir, 0);
            }
        },
    };
}

//

            ],
            "#": () => [
                sprite("Boss"),
                area(),
                body(),
                chaseAndFlee(),
                anchor("bot"),
                scale(3),
                "Boss",
            ],



 player.onCollide("Boss", (boss, col) => {
        if (col.isBottom()) {

            destroy(boss);
        } else {

            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	Get close to boss	Boss moves towards player	As expected	Pass
2	Get far from boss	Boss runs away	As expected	Pass

Evidence