I am working on a new smoother 'follow-the-leader' movement code for a snake. Hope to have it up and running soon.
Tezuka wrote ...
2012/11/10
Move the snake
what should i do to increase the pixar, is there anyway so the snake eats the food?
In your 'updateFoodLocation' method, make sure that the food is placed at locations that the snake will end up at (multiples of 20).
Or add a method in your Snake class returning a boolean indicating if Food intersects the 'head' called with snakeBody.eats():
That way, all the food need do is intersect the head; instead of having to be placed exactly where the head is.
public boolean eats()
{
Food food = (Food) getOneIntersectingObject(Food.class);
if (food != null)
{
getWorld().removeObject(food);
return true;
}
return false;
}I want to call this method from snake class how should i do private void growSnake(int x, int y)?
Since all the 'intersect' or 'inRange' methods are protected in the Actor class API, your only option would be to write your own 'intersect' method(s). That would mean "for each object (of whatever class), if snakeBody.getX() is between Actor object.getX() - Actor object.getImage().getWidth()/2 and Actor object.getX() + Actor object.getImage().getWidth()/2 AND snakeBody.getY() is between ...==== return true; else, return false.
One thing I have noticed is that when you initially place your snake body segments into the world, you are placing them 15 pixels apart from each other. With that, your segments need to move at distances of 15; and your food needs to placed at multiples of 15 (between 15 and the last multiple of 15 before the length of width or height of the world).
Having done that, you can just see if they are at the same location with something like the following
int newX = snakeBody[0].getX();
int newY = snakeBody[0].getY();
if (!getObjectsAt(newX, newY, Food.class).isEmpty())
{
removeObjects(getObjectsAt(newX, newY, Food.class));
growSnake();
}I said 'something like'. Instead of 'growSnake();' set the boolean 'eaten' to 'true' and refer to it after you move all the segments of the snake, except the last one. Before moving the last one, check 'eaten' and add a segment at that location, if neccessary. The only time you will grow the snake is during that time, so there is no need to have a seperate method for it. Include it right in the 'for' loop
if (i == snakeBody.length - 1)
{
if (eaten)
{
eaten = false;
// add the new segment at coordinates (snakeBody[i].getX(), snakeBody[i].getY())
// add new segment to the array, etc.
}
}import greenfoot.*;
/**
* This is MyWorld class in which game runs.
*
* @author Chandrasekhar Thotakura
* @version 1.0.0
*/
public class MyWorld extends World
{
/**
* Defines the variables required in game.
*/
private Snake snakeBody[];
private Food food;
private Counter score;
private int direction;
private boolean eaten;
private int gameState;
private int speed;
private int speedX;
private int speedY;
int previousLocationX;
int previousLocationY;
/**
* Constructor for objects of class MyWorld.
*/
public MyWorld()
{
super(300, 450, 1); // constructor of the super class
direction = 0; // initialization
eaten = true;; // initialization
speed = 15;
speedX = speed;
speedY = 0;
setBackground("bluerock.jpg");
for (int i = 0; i < 1; i++)
{
int x = (Greenfoot.getRandomNumber(18) + 1) * 15 + 10;
int y = (Greenfoot.getRandomNumber(18) + 1) * 15 + 10;
addObject(new Food(), x, y);
}
score = new Counter("Score : "); // initialization of the food
addObject(score, 19*15, 8); // adding food actor to the world
snakeBody = new Snake[3]; // initialization of the Snake
for(int i=0; i<snakeBody.length; i++)
{
snakeBody[i] = new Snake(i==0);
addObject(snakeBody[i], 90+(snakeBody.length-i)*15, 30); // adding snake actor to the world
}
}
/**
* Game starts from here.
*/
public void act()
{
move();
checkKey();
}
/**
* This method will update the length of the Snake.
*/
private void growSnake(int x, int y)
{
Snake s = new Snake(false);
Snake oldSnake[] = new Snake[snakeBody.length];
for(int i=0; i<snakeBody.length; i++)
{
oldSnake[i] = snakeBody[i];
}
snakeBody = new Snake[snakeBody.length+1];
for(int i=0; i<snakeBody.length-1; i++)
{
snakeBody[i] = oldSnake[i];
}
snakeBody[snakeBody.length-1] = s;
addObject(snakeBody[snakeBody.length-1], x, y); // adds new snake body actor
}
/**
* This method will changes the place where the food is displayed.
*/
private void updateFoodLocation()
{
int x=0, y=0;
boolean overlap = true;
eaten = false;
while(overlap)
{
x = Greenfoot.getRandomNumber(getWidth()/15);
y = Greenfoot.getRandomNumber(getHeight()/15);
for(int i=0; i<snakeBody.length; i++)
{
// Condition to check food will not touch the snake
if(x!=snakeBody[i].getX() || y!=snakeBody[i].getY())
{
overlap = false;
break;
}
}
}
food.setLocation(x*15, y*15);
}
public void checkKey()
{
if(Greenfoot.isKeyDown("right")) // checks if right key is pressed
{
if(direction==1 || direction==3)
{ direction = 0;
speedX = speed;
speedY = 0;
}
}
else if(Greenfoot.isKeyDown("down")) // checks if down key is pressed
{
if(direction==0 || direction==2)
{direction = 1;
speedX = 0;
speedY = speed;
}
}
else if(Greenfoot.isKeyDown("left")) // checks if left key is pressed
{
if(direction==1 || direction==3)
{direction = 2;
speedX = -speed;
speedY = 0;
}
}
else if(Greenfoot.isKeyDown("up")) // checks if up key is pressed
{
if(direction==0 || direction==2)
{ direction = 3;
speedX = 0;
speedY = -speed;
}
}
}
private void move()
{
// save the location of the 'head' segment (segment in front)
// these are the 'goto' values for the next segment
previousLocationX = snakeBody[0].getX();
previousLocationY = snakeBody[0].getY();
// move head
snakeBody[0].setLocation(snakeBody[0].getX()+ speedX, snakeBody[0].getY()+speedY); // moves one step
// move body
if(snakeBody[0].getX()!=previousLocationX || snakeBody[0].getY()!=previousLocationY) // Checks if the snake hits walls
{
for(int i=1; i<snakeBody.length; i++)
{
int holdX = snakeBody[i].getX();
int holdY = snakeBody[i].getY();
snakeBody[i].setLocation(previousLocationX, previousLocationY);
// set 'goto' values for next segment
previousLocationX = holdX;
previousLocationY = holdY;
if( i == snakeBody.length-1)
{
if(eaten)
{
updateFoodLocation();// updates the location of the food
growSnake(previousLocationX, previousLocationY);
score.add(5);
}
}
}
for(int i=1; i<snakeBody.length; i++) // Checks if the snake eats itself
{
if(snakeBody[0].getX()==snakeBody[i].getX() && snakeBody[0].getY()==snakeBody[i].getY())
{
die();
}
}
}
else
{
die();
}
}
public void die()
{
setBackground("GameOver.jpg");
addObject(score, 19*15, 8);
}
}
sorry here it is
java.lang.NullPointerException
at MyWorld.updateFoodLocation(MyWorld.java:114)
at MyWorld.move(MyWorld.java:179)
at MyWorld.act(MyWorld.java:65)
at greenfoot.core.Simulation.actWorld(Simulation.java:571)
at greenfoot.core.Simulation.runOneLoop(Simulation.java:506)
at greenfoot.core.Simulation.runContent(Simulation.java:213)
at greenfoot.core.Simulation.run(Simulation.java:203)
nvm I got it, now I just need a method to add the segment. I erased the growmethode()
can u explain this for me iam not getting it
Snake s = new Snake();
Snake oldSnake = new Snake;
for(int i=0; i<snakeBody.length; i++)
{
oldSnake = snakeBody;
}
snakeBody = new Snake
for(int i=0; i<snakeBody.length-1; i++)
{
snakeBody = oldSnake;
}
snakeBody = s;
addObject(snakeBody, previousLocationX, previousLocationY); // adds new snake body actor
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