Why, in my game, is the lives value decreasing to 0 immediately after colliding with the square when it should just reduce by 1

Question

I am trying to make a game the sends squares at you and you have to avoid them by moving your mouse that controls a circle around them.

I added a lives value to add more to the game, and set up collision detection so that as soon as the distance from the middle of the circle to the square was less than the radius of the circle, it took away a life. This collision detection works, it's just that in my if statements that detect collision I added "lives = lives - 1;", but as soon as they collide, the lives value drops instantly to 0.

float centerY = 250;
float centerX = 175;
float lives = 3;
float rectY1 = random(0,500);
float rectX1 = random(0,500);
float rectY2 = random(0,500);
float rectX2 = random(0,500);
float rectY3 = random(0,500);
float rectX3 = random(0,500);
float rectY4 = random(0,500);
float rectX4 = random(0,500);
float rectY5 = random(0,500);
float rectX5 = random(0,500);
float rectY6 = random(0,500);
float rectX6 = random(0,500);

int score = 0;
int squareRadius = 15;

void setup(){
  size(500,500);
  background(155);
}


void draw(){
  boolean gameOver = false;
  boolean lifeLost = false;

  background(155);

  fill(149,185,215);
  ellipse(centerX,centerY,30,30);

  centerX = mouseX;
  centerY = mouseY;
  fill(0);
  rect(rectX1,rectY1,30,30);
  rect(rectX2,rectY2,30,30);
  rect(rectX3,rectY3,30,30);
  rect(rectX4,rectY4,30,30);

  rectX1 = rectX1 - 5;
  rectX2 = rectX2 - 5;
  rectX3 = rectX3 - 5;
  rectX4 = rectX4 - 5;
  rectX5 = rectX5 - 5;

  if(rectX1 + 30 < 0){
    rectX1 = 500;
    rectY1 = random(0,600);
    score = score + 1;
  }
  if(rectX2 + 30 < 0){
    rectX2 = 500;
    rectY2 = random(0,600);
    score = score + 1;
  }
  if(rectX3 + 30 < 0){
    rectX3 = 500;
    rectY3 = random(0,600);
    score = score + 1;
  }
  if(rectX4 + 30 < 0){
    rectX4 = 500;
    rectY4 = random(0,600);
    score = score + 1;
  }
  if(rectX5 + 30 < 0){
    rectX5 = 500;
    rectY5 = random(0,600);
    score = score + 1;
  }
  if(dist(mouseX,mouseY,rectX1,rectY1) < 30){
    lifeLost = true;
  }
  if(dist(mouseX,mouseY,rectX2,rectY2) < 30){
    lifeLost = true;
  }
  if(dist(mouseX,mouseY,rectX3,rectY3) < 30){
    lifeLost = true;
  }
  if(dist(mouseX,mouseY,rectX4,rectY4) < 30){
    lifeLost = true;
  }
  if(lifeLost == true){
    lifeLost = false;
    lives = lives - 1;
  }
  if(lives == 0 || lives < 0){
    gameOver = true;
  }
  text("Lives:",20,20);
  if(lives == 3){
    fill(255,0,0);
    ellipse(60,15,10,10);
    ellipse(80,15,10,10);
    ellipse(100,15,10,10);
  }
  if(lives == 2){
    fill(255,0,0);
    ellipse(60,15,10,10);
    ellipse(80,15,10,10);
  }
  if(lives == 1){
    fill(255,0,0);
    ellipse(60,15,10,10);
  }
  if(lives == 0){
    text("Game over.",250,250);
  }
  fill(0);
  if(gameOver == false){
    text("Score: " + score,120,20);
  }
  else{
    background(0);
    text("Score: Game Over",120,20);
    fill(255);
    text("Game over. Press Space to continue.",150,250);
  }
  if(score > 50){
    fill(0);
    rect(rectX5,rectY5,30,30);
    if(score > 50 && score < 60){
      text("You have reached a score of 50. Adding another square.",100,250);
    }
  }

  if(gameOver == true){
    if(keyPressed){
      if(key == 32){
        gameOver = false;
        lives = 3;
        score = 0;
        background(55);
      } 
    }
  }
}

My guess is once you lose a life nothing changes so the next call to `draw` you will lose another life and so on. Looks like it is not all happening within a single call to `draw`. — John3136, Oct 11 '18 at 02:19
It's well worth investing the time in learning [how to use a debugger](https://stackoverflow.com/questions/25385173/what-is-a-debugger-and-how-can-it-help-me-diagnose-problems). It's ideal for solving problems like this one. — dave, Oct 11 '18 at 02:29

score 2 · Answer 1 · answered Oct 11 '18 at 02:37

2

I recommend that immediately after reducing the lives value, move the player far enough away from the square that it won't constantly reduce the lives until it hits 0. The lives is immediately dropping down to zero because there is not enough buffer time for the player to stop being in contact with the square, therefore, life points are taken away constantly as long as the player is in contact with the block.

answered Oct 11 '18 at 02:37

ıllıllı кιмσтσ ıllıllı

66
7

Would it be possible to add a boolean such as takeLife and set it to true if they make contact and then later have an if statement that if it is true, it takes away one life and then sets it to false? – user10487132 Oct 11 '18 at 13:16
Yes that is possible. Try that and see how it works. If not, try other methods of executing this since there are many ways to do one task in Java. (Also, are you using a plug-in for processing such as Proclipsing?). – ıllıllı кιмσтσ ıllıllı Oct 12 '18 at 02:51

roboot · Answer 2 · 2018-10-11T03:53:16.713

As кιмσтσ said, the lives counter is decreasing constantly while the player is in contact with the square.

If you do invest time into learning to use a debugger as dave mentioned, you should be able to step through the iterations of your draw function and notice that the lives counter is in fact decreasing by one per call of the function!

The problem is that the player remains in contact with the square and is still damage-able during this time. There are a couple ways to solve this: The easiest and most obvious way is to teleport the player somewhere safe before the next call to draw or to just delete the square that is damaging them, but this can come across as inelegant. A more interesting approach would be to change the player's state so that they are unable to lose lives and then change the state back after a set time has passed. This might be a bit more tricky to implement but could prove to be a fun challenge!

Why, in my game, is the lives value decreasing to 0 immediately after colliding with the square when it should just reduce by 1

2 Answers2