Created Object sticks to the screen and does not move with the map

Question

The problem is about creating objects on the map. Everything would be fine, but suddenly I can only create the objects (which are images), on the screen. Whenever I give some cordination to an object it takes the (0,0) point of the screen, not the map. So I can move my guy around the map (camera works correctly), but for example spider stays on screen, instead on the map. Here intialization of objects:

static float PlayerPositionX = 0;
static float PlayerPositionY = 0;
static GameContainer gc; 
static StateBasedGame sbg;

//Spider
Monster monster = new Monster();

float shiftXSpider;
float shiftYSpider;

//Player position at the middle of the screen *half of the screen
static float shiftX = PlayerPositionY + (Game.screenWidth/2);
static float shiftY = PlayerPositionX + (Game.screenHeight/2);
static float shiftXMap = PlayerPositionX;
static float shiftYMap = PlayerPositionY;

This is my render method for map, spider and player. (Just a part, of course)

worldMap.draw(PlayerPositionX,PlayerPositionY);
player.draw(shiftX,shiftY);
spider.draw(spiderPoint.x, spiderPoint.y);

Update method:

public void update(GameContainer gc, StateBasedGame sbg, int delta) throws SlickException {
    System.out.println(playerPoint.getX() + " " + playerPoint.getY());
    playerPoint.x=PlayerPositionX;
    playerPoint.y=PlayerPositionY;
    Input input = gc.getInput();
    monster.Chase(playerPoint.x, playerPoint.y,delta);
    // monster.Chase(PlayerPositionX, PlayerPositionY,delta);
    // shiftXSpider=monster.getMonsterPositionX();
    // shiftYSpider=monster.getMonsterPositionY();
    spiderPoint.x=monster.getMonsterPositionX();
    spiderPoint.y=monster.getMonsterPositionY();

    if(input.isKeyDown(input.KEY_DOWN)) {
        player=movingDown;
        PlayerPositionY-=delta * .1f;
        if(PlayerPositionY<-600) {
            PlayerPositionY+=delta * .1f;
        }
    }
    //move up
    if(input.isKeyDown(input.KEY_UP)) {
        player=movingUp;
        PlayerPositionY+=delta * .1f;
        if(PlayerPositionY>162) {
            PlayerPositionY-=delta * .1f;
        }
    }
    //move right
    if(input.isKeyDown(input.KEY_RIGHT)) {
        player=movingRight;
        PlayerPositionX-=delta * .1f;
        if(PlayerPositionX<-840) {
            PlayerPositionX+=delta * .1f;
        }
    }
    //move left
    if(input.isKeyDown(input.KEY_LEFT)) {
        player=movingLeft;
        PlayerPositionX+=delta * .1f;
        if(PlayerPositionX>324) {
            PlayerPositionX-=delta * .1f;
        }
    }
}

Maybe you should ask this in http://gamedev.stackexchange.com/ — Daniel Kaplan, Jan 10 '13 at 05:44
In your init method you initialize these shiftXSpider and shiftYSpider. However you do not modify these in the update method nor do you use these in the render method for rendering the spider. — Niklas, Jan 11 '13 at 12:03

score 0 · Accepted Answer · answered Apr 10 '13 at 14:15

I did this with a camera class.
Here you can find all my classes: http://pastebin.com/u/huneater
My little game (unfinished): https://www.dropbox.com/s/dhvf5vbqj25sgyw/game.jar

My rendering for an example rectangle:

@Override
    public void render(GameContainer gc, Graphics g, Camera camera) {
        g.setColor(color);
        g.fillRect(x - camera.getX(), y - camera.getY(), width, height);
    }

For this camera class you should set the targetX & targetY positions in your players update method:

float targetX = x - (gc.getWidth() / 2);
camera.setTargetX(targetX);

float targetY = y - (gc.getHeight() / 2);
camera.setTargetY(targetY);

And then in your world's update loop you have to call the camera's update loop. So with this, ive got a player in the midlle of my screen, with some blocks in map. And they are perfectly positioned.

Created Object sticks to the screen and does not move with the map

1 Answers1