Space Invaders | KTBYTE Student Projects

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<iframe width='500px' height='400px' src='https://nest.ktbyte.com/nest#299621' allowfullscreen></iframe>

int[][] board = new int[20][20];
int gridSize = 30;
int EMPTY = 0;
int SNAKE = 1;
int APPLE = 2;
int direction = LEFT;
int MAXLENGTH = 400;
int snakeLength = 1;
int[] snakeX = new int[MAXLENGTH];
int[] snakeY = new int[MAXLENGTH];
int tailX, tailY;
int snakeDirection = LEFT;
int appleX = (int)random(0,20);
int appleY = (int)random(0,20);
int snakeSpeed = 15;
boolean grow = false;
int slide = 1;
int buttonX = 300;
int buttonY = 400;

int speed1X = 150;
int speed1Y = 300;
int speed2X = 300;
int speed2Y = 300;
int speed3X = 450;
int speed3Y = 300;

void setup(){
    size(600,600);
    snakeX[0] = 10;
    snakeY[0] = 10;
    textAlign(CENTER,CENTER);
}
void draw(){
    if(slide == 1){
        startScreen();
    }
    if(slide == 2){
        if(frameCount % snakeSpeed == 0){
            moveSnake();
            drawSnake();
            checkCollision();
        }
        playerControls();
        drawApple();
        drawBoard();
    }
    if(slide == 3){
        chooseSpeed();
    }
}
void drawBoard(){
    for(int i = 0; i < 20; i++){
        for(int j = 0; j < 20; j++){
            if(board[i][j] == EMPTY){
                if(i == 0 || j == 0 || i == 19 || j == 19){
                    fill(0,0,255);
                }else{
                    fill(255);
                }
                strokeWeight(3);
                rect(i*gridSize,j*gridSize,gridSize,gridSize);
            }
            if(board[i][j] == SNAKE){
                fill(0,255,0);
                strokeWeight(3);
                rect(i*gridSize,j*gridSize,gridSize,gridSize);
            }
            if(board[i][j] == APPLE){
                fill(255,0,0);
                strokeWeight(3);
                rect(i*gridSize,j*gridSize,gridSize,gridSize);
            }
        }
    }
}
void keyPressed(){
    if(keyCode == LEFT){
        snakeDirection = LEFT;
    }
    if(keyCode == RIGHT){
        snakeDirection = RIGHT;
    }
    if(keyCode == DOWN){
        snakeDirection = DOWN;
    }
    if(keyCode == UP){
        snakeDirection = UP;
    }
}
void moveSnake(){
    tailX = snakeX[snakeLength - 1];
    tailY = snakeY[snakeLength - 1];
    for(int i = snakeLength; i > 0; i--){
        snakeX[i] = snakeX[i - 1];
        snakeY[i] = snakeY[i - 1];
    }
    if(direction == LEFT){
        snakeY[0]-=1;
    }else if(direction == RIGHT){
        snakeY[0]++;
    }else if(direction == DOWN){
        snakeX[0]++;
    }else if(direction == UP){
        snakeX[0]--;
    }
}
void drawSnake() {
    for(int i=0; i<snakeLength; i++) {
        board[snakeY[i]][snakeX[i]] = SNAKE;
    }
    if(grow){
        snakeX[snakeLength] = tailX;
        snakeY[snakeLength] = tailY;
        grow = false;
        snakeLength++;
    }else{
        board[tailY][tailX] = EMPTY;
    }
}
void playerControls(){
    if(direction != RIGHT){
    if(snakeDirection == LEFT){
        direction = LEFT;
    }
    }
    if(direction != LEFT){
    if(snakeDirection == RIGHT){
        direction = RIGHT;
    }
    }
    if(direction != DOWN){
    if(snakeDirection == UP){
        direction = UP;
    }
    }
    if(direction != UP){
    if(snakeDirection == DOWN){
        direction = DOWN;
    }
    }
}
void drawApple(){
    board[appleY][appleX] = APPLE;
    if(appleY == 0 || appleX == 0 || appleY == 19 || appleX == 19){
        board[appleY][appleX] = EMPTY;
        appleY = (int)random(0,20);
        appleX = (int)random(0,20);
    }
    if(snakeY[0]*gridSize == appleY * gridSize && snakeX[0] * gridSize == appleX * gridSize){
        board[appleY][appleX] = SNAKE;
        grow = true;
        appleY = (int)random(0,20);
        appleX = (int)random(0,20);
    }
}
void checkCollision(){
    for(int i = 1; i < snakeLength; i++){
        if(snakeX[0] == snakeX[i] && snakeY[0] == snakeY[i]){
            reset();
        }
    }
    for(int i = 0; i < snakeLength; i++){
        if(snakeY[i] == 0){
            slide = 1;
        }
        if(snakeY[i] == 19){
            slide = 1;
        }
        if(snakeX[i] == 0){
            slide = 1;
        }
        if(snakeX[i] == 19){
            slide = 1;
        }
    }
}
void reset(){
    for(int i = 0; i < 20; i++){
        board[snakeY[i]][snakeX[i]] = EMPTY;
    }    
    snakeLength = 1;
    snakeX[0] = 10;
    snakeY[0] = 10;
}
void startScreen(){
    textAlign(CENTER,CENTER);
    fill(0,0,255);
    textSize(45);
    text("Snake",300,150);
    textSize(25);
    text("By: Pierce Zhao",300,200);
    fill(255);
    ellipse(buttonX,buttonY,200,200);
    fill(0,0,255);
    text("PLAY",buttonX,buttonY);
}
void mousePressed(){
    if (slide == 1){
    if(dist(mouseX,mouseY,buttonX,buttonY) <= 100){
        reset();
        slide = 3;
    }
    }
}
void chooseSpeed(){
    background(200);
    fill(255);
    ellipse(speed1X,speed1Y,100,100);
    ellipse(speed2X,speed2Y,100,100);
    ellipse(speed3X,speed3Y,100,100);
    fill(0,0,255);
    textSize(20);
    text("Slow",speed1X,speed1Y);
    text("Normal",speed2X,speed2Y);
}

DESCRIPTION