simple snake game - libgdx - libgdx

Question

I'm trying to develop a simple snake game with libgdx. My problem is that everytime I want to spawn some apples(texture, 20px width X 20px height) it always overlaps the body of the snake.
I'm trying to avoid this but it keeps occuring during the game.
The snake is compiled of parts - every part is a texture of 20px width X 20px height(The screen width is 480px width X 800px height)
Here is what I have tried so far:
public void addApple() {
accomplishedSnake = false;
accomplishedApples = false;
while (!accomplishedSnake && !accomplishedApples) {
xApple = 20 * MathUtils.random(0, 23);
yApple = 20 * MathUtils.random(20, 36);
if (!accomplishedSnake) {
for (int i = 0; i < snake.getSize(); i++) {
if (snake.getPart(i).getX() <= xApple
&& snake.getPart(i).getX() + 20 >= xApple
&& yApple >= snake.getPart(i).getY()
&& yApple <= snake.getPart(i).getY() + 20)
break;
if (i == snake.getSize() - 1) {
accomplishedSnake = true;
break;
}
}
}
if (!accomplishedApples) {
for (int i = 0; i < apples.size; i++) {
if (apples.get(i).getX() <= xApple && apples.get(i).getX()+20 >= xApple
&& yApple >= apples.get(i).getY() && yApple <= apples.get(i).getY()+20)
break;
if (i == apples.size - 1) {
accomplishedApples = true;
break;
}
}
}
}
apples.add(new Apple(xApple, yApple));
}
The code is pretty self-explanatory. In every moment I have 3 different apples on the screen. This code tries to raffle x-y coordinates to the new apple but before the apple is added to the screen and rendered, I want to make sure that it doesn't overlaps the body of the snake or the other apples.
I just can't see what's wrong with this code.
P.S I tried to use the overlaps method in the Rectangle class but it doesn't work.

Answer 1

You test conditions are too simple. Each item snake body part/apple has size, you need to consider their locus. So [snake.X,snake.X+20] and [snake.Y,snake.Y+20] is occupied by each body part, you need to ensure both apple.X and apple.X+20 aren't in range, the same for apple.Y

Answer 2

try this ..
if (snake.getPart(i).getX() >= xApple
&& snake.getPart(i).getX() + 20 <= xApple
&& snake.getPart(i).getX() >= xApple+20
&& snake.getPart(i).getX() + 20 <= xApple+20
&& snake.getPart(i).getY() >= yApple
&& snake.getPart(i).getY() + 20 <= yApple
&& snake.getPart(i).getY() >= yApple +20
&& snake.getPart(i).getY() + 20 <= yApple +20)
break;
also you need to ensure accomplishedApple and accomplishedSnake are set to false both before entering the while loop and after each calculation of random coordinates.
you also need to mimic this logic when establishing accomplishedApple further down your code.

Answer 3

This game should be tile-based.
This means, that the game is organized as a grid, where every cell has the same size.
This is done by using a camera:
OrthographicCamera cam = new OrthographicCamera(viewportWidth, viewportHeight)
The viewportWidth and viewportHeight define how many cells there should be in x and y.
As you are using a resolution of 480*800px and pictures with a size of 20*20px, the viewportWidth should be 480/20=24 and the viewportHeight should be 800/20 = 40.
Note, that the cameras P(0/0) is in the middle of the screen and you see objects from -12 to 12 (x) and -20 to 20 (y). Just set the position of the camera to P(12/20) and the P(0/0) is the lower left corner, as usual.
Now the spawning would be easy:
I use a int[][] world, where i store, if there is a:
Snakepart at P(x,y) (world[x][y] == 1)
Apple at P(x,y) (world[x][y] == 2)
Nothing at P(x,y) (world[x][y] == 0)
This means, that if the snake leaves a tile, you need to set its value to 0 (world[x][y] = 0) and every tile it enters to 1 (world[x][y] = 1)
public void spawnApple() {
boolean spawned = false;
while(!spawned) {
// The lower left corner is always an int-value
int x = (int)MathUtils.random(0, 23);
int y = (int)MathUtils.random(0, 40);
if (world[x][y] == 0) {
// Add Apple at x,y
world[x][y] = 2;
}
}
}
Hope it helps!

Answer 4

private void checkAndPlaceApple() {
if(!appleAvailable) {
do {
appleX = MathUtils.random(Gdx.graphics.getWidth / 20 - 1) * 20;
appleY = MathUtils.random(Gdx.graphics.getHeight / 20 - 1) * 20;
appleAvailable = true;
} while(appleX == snakeX && appleY == snakeY);
}
}
The previous code shows the required rule for placing the apple on the
screen. First, we check whether we need to place an apple, then we randomly pick
a location on the screen, which is a multiple of 20, and we repick it if the picked location contains the snake. As we are working in a 0-indexed environment we need to subtract one (1-20 becomes 0-19 and 1-15 becomes 0-14).