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Thread: 2D Platformer - Collisions only working on two sides of an object. Why?

  1. #1
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    Unhappy 2D Platformer - Collisions only working on two sides of an object. Why?

    Hello, I am designing a 2D platformer game. Currently, the player moves around in stages, when the player moves off the screen, a new stage is loaded. The player can move around (and float - I have not implemented gravity) and I'm trying to code collision so that the player cannot move through any obstacles. Currently, it works on the left and top sides of every obstacle, however, on the bottom and right side, it does not work despite the code being the same.
    Here is my code for the Grogu (player) class:
    public class Grogu {
        //Image
        public Image currentGroguImage;
        String which = "Default";
        int step = 0;
        int frames = 0;
     
        //Position
        int x,y;
        int w,h;
     
        float xSpeed,ySpeed;
        Input input;
     
        public Grogu(int x, int y) {
            this.x = x;
            this.y = y;
            input = new Input(1);
            xSpeed = 0;
            ySpeed = 0;
     
        }
     
        public void update() {  
            move();
        }
     
        public void render(Graphics g) {
            //g.drawString("" + collision, Main.getScreenWidth()/2, Main.getScreenHeight()/2);
            g.drawImage(currentGroguImage,x, y);
        }
     
        public void move() {    
            x+=xSpeed;
            y+=ySpeed;
        }
     
        public void keyPressed(int key, char c)
        {
     
            if(key == Input.KEY_A) {
                xSpeed = -7;
            }
     
            if(key == Input.KEY_D) {
                xSpeed = 7;
            }
     
            if(key == Input.KEY_W) {
                ySpeed = -7;
            }
     
            if(key == Input.KEY_S) {
                ySpeed = 7;
            }
     
            if(key == Input.KEY_D) {
                which = "Right";
            }
            else if(key == Input.KEY_A) {
                which = "Left";
            }
        }
     
        public void keyReleased(int key, char c) {
            if(key == Input.KEY_D || key == Input.KEY_A) {
                which = "Default";
            }
            if(key == Input.KEY_A) {
                xSpeed = 0;
            }
     
            if(key == Input.KEY_D) {
                xSpeed = 0;
            }
     
            if(key == Input.KEY_W) {
                ySpeed = 0;
     
            }
     
            if(key == Input.KEY_S) {
                ySpeed = 0;
            }
        }
     
        public Rectangle getBounds() {
            Rectangle r = new Rectangle(x - (int)xSpeed,y - (int)ySpeed,currentGroguImage.getWidth() + (int)xSpeed * 2,currentGroguImage.getHeight() + (int)ySpeed * 2);
            return r;
        }
     
        public void setX(int s) {
            x = s;
        }
        public void setY(int s) {
            y = s;
        }
     
        public int getX() {
            return x;
        }
        public int getY() {
            return y;
        }
        public float getXSpeed() {
            return xSpeed;
        }
        public float getYSpeed() {
            return ySpeed;
        }
        public int getWidth() {
            return currentGroguImage.getWidth();
        }
        public int getHeight() {
            return currentGroguImage.getHeight();
        }
    }

    And here is my stage class, where the collisions are detected and dealt with:
    public class Stage {
        public ArrayList<Obstacle> obstacles = new ArrayList<Obstacle>();
        public ArrayList<Enemy> enemies = new ArrayList<Enemy>();
        Grogu grogu;
        public Stage() {
            grogu = new Grogu(75,5*Main.getScreenHeight()/6 - Images.frontGrogu.getHeight()/2);
        }
        public void update() {
            checkCollisions();
            grogu.update();
     
        }
     
        public void render(Graphics g) {
     
            for(Obstacle o: obstacles) {
                o.render(g);
            }
     
            grogu.render(g);
        }
     
        public void keyPressed(int key, char c) {
            grogu.keyPressed(key, c);
        }
     
        public void keyReleased(int key, char c) {
            grogu.keyReleased(key, c);
        }
     
        private void checkCollisions() {
            for(Obstacle o: obstacles) {
                if(grogu.getBounds().intersects(o.getBounds())) {
                    o.setR();
                    if(grogu.getX() + grogu.getWidth() <= o.getX()) {
                        grogu.setX(grogu.getX() - (int)grogu.getXSpeed() - 1);
                    }
                    if(grogu.getX() > o.getX() + o.getWidth()) {
                        grogu.setX(grogu.getX() - (int)grogu.getXSpeed() + 1);
                    }
                    if(grogu.getY() + grogu.getHeight() <= o.getY()) {
                        grogu.setY(grogu.getY() - (int)grogu.getYSpeed() - 1);
                    }
                    if(grogu.getY() >= o.getY() + o.getHeight()) {
                        grogu.setY(grogu.getY() - (int)grogu.getYSpeed() + 1);
                    }
                    //return grogu.collision =true;
                }
            }
        }
    }

  2. #2
    Super Moderator Norm's Avatar
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    Default Re: 2D Platformer - Collisions only working on two sides of an object. Why?

    How can the the program be compiled and executed for testing?
    If you don't understand my answer, don't ignore it, ask a question.

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