使用for循环在地面上绘制块

Question

I am using slick2d to make a mario type clone game. We have 50x50 images we are using as blocks that was going to be on the floor. Whenever I put this code into the for loop, I can see the block being drawn and redrawn all the way to the end of the specified area, instead of drawing a block every 50 pixels.

package edu.bsu.cs222.finalProject.states;



public class GameState extends BasicGameState {

int stateID = 1;
Image background;
Image block;
float x = 0;
float y = -370;
float Dx = x + 200;
float Dy = y + 810;
private float verticalSpeed = 0.0f;
private float horizontalSpeed = 1.8f;
private float imagepositionx=0;
private float imagepositiony=500;
boolean jumping = false;
Animation cowboy, movingLeft, movingRight, movingUp, stoppedLeft,
        stoppedRight;
int[] animationDuration = { 200, 200 };

public GameState(int stateID) {
    this.stateID = stateID;
}

@Override
public void init(GameContainer gc, StateBasedGame sbg)
        throws SlickException {
    background = new Image("res/ui/background.png");
    block = new Image("res/obj/block.png");
    Image[] walkLeft = { new Image("res/char/cowboyleft1.png"),
            new Image("res/char/cowboyleft2.png") };
    Image[] walkRight = { new Image("res/char/cowboyright1.png"),
            new Image("res/char/cowboyright2.png") };
    Image[] stopLeft = { new Image("res/char/cowboyleft1.png"),
            new Image("res/char/cowboyleft2.png") };
    Image[] stopRight = { new Image("res/char/cowboyright1.png"),
            new Image("res/char/cowboyright2.png") };
    movingLeft = new Animation(walkLeft, animationDuration, true);
    movingRight = new Animation(walkRight, animationDuration, true);
    stoppedLeft = new Animation(stopLeft, animationDuration, false);
    stoppedRight = new Animation(stopRight, animationDuration, false);
    cowboy = stoppedRight;
}

@Override
public void render(GameContainer gc, StateBasedGame sbg, Graphics g)
        throws SlickException {
    background.draw(x, y);
    g.drawString("Cowboy's X:" + x + "\nCowboy's Y: " + y, 400, 20);
    cowboy.draw(Dx, Dy);


        if(imagepositionx <3000)
        {
            g.drawImage(block, imagepositionx, imagepositiony);
            imagepositionx += 50;
        }



            //pillar1
    block.draw(600, 450);
    block.draw(600, 400);
    g.drawImage(block, 600, 400);
    g.drawImage(block, 600, 350);
    //3 in air
    g.drawImage(block, 800, 250);
    g.drawImage(block, 850, 250);
    g.drawImage(block, 900, 250);
    //pillar2
    g.drawImage(block, 1100, 450);
    g.drawImage(block, 1100, 400);
    g.drawImage(block, 1100, 350);

}

@Override
public void update(GameContainer gc, StateBasedGame sbg, int delta)
        throws SlickException {
    Input input = gc.getInput();
    if (input.isKeyDown(Input.KEY_LEFT)) {
        cowboy = movingLeft;
        x += horizontalSpeed;
        if (x > 0) {
            x -= delta * horizontalSpeed;
        }
    }

    if (input.isKeyDown(Input.KEY_RIGHT)) {
        cowboy = movingRight;
        x -= horizontalSpeed;
        if (x < -2975.0) {
            x += delta * horizontalSpeed;
        }
    }

    if (input.isKeyDown(Input.KEY_UP) && !jumping) {
        verticalSpeed = -3.0f;
        jumping = true;
    }

    if (jumping) {
        verticalSpeed += .03f * delta;
    }

    if (Dy > 470) {
        jumping = false;
        verticalSpeed = 0;
        Dy = 470;
    }
    Dy += verticalSpeed;
}

@Override
public int getID() {
    return stateID;
}

}

Also running into a problem using this code they move on the screen rather then stay in a fixed position.

g.drawImage(block, 600, 400);

Answer 1

If i understand you correctly, you mean the same one block is being drawn then like its being erased and redrawn in the new position? You only see the one block until the end of the loop?

If that's the case you need to create a NEW block for every position.

As for the second part where the block is not staying in place. It is staying in place. Whats happening is every time you call this:

g.drawImage(block, 600, 400);

Your block is placed in the same place on the screen. So technically your block isn't moving.

If what you are trying to do is like mario where your character moves forward and everything goes backwards to emulate the look of traveling through the level then you need to update the positions of everything.

If you move forward a certain amount set the position of objects back -50px or something like that. If you move backwards, set the position of objects forward +50px.

I hope I make sense, it's kinda weird to explain.