Pongを作る(7)　色で遊ぶ

点数が変わるたびに色が変わるようにしましょう。

点数が入るたびに、draw() 内の background() の値が変わるようにしてみます。
新しい変数として、赤（r）、緑（g）、青（b）を追加します。

//　以下を追加
int r, g, b;
// setup()内　以下を追加
r = 0;
g = 0;
b = 0;
// draw()内　以下を修正
background(0);
↓　以下に修正
background(r, g, b);
------------------------------
if (ballX+3 > width) {
  enemyScore ++;
  ballX = width/2;
  ballY = height/2;
  xSpeed = random(1, 4);
  ySpeed = random(1, 4);
}
else if(ballX-3 < 0) { 
  myScore ++; 
  ballX = width/2; 
  ballY = height/2; 
  xSpeed = random(1, 4); 
  ySpeed = random(1, 4); 
} 
↓　以下に修正 
if (ballX+3 > width) {
  enemyScore ++;
  ballX = width/2;
  ballY = height/2;
  xSpeed = random(1, 4);
  ySpeed = random(1, 4);
  r = int(random(256));
  g = int(random(256));
  b = int(random(256));
}
else if(ballX-3 < 0) {
  myScore ++;
  ballX = width/2;
  ballY = height/2;
  xSpeed = random(1, 4);
  ySpeed = random(1, 4);
  r = int(random(256));
  g = int(random(256));
  b = int(random(256));
}

なお、r = int(random(256));　と記述すると、整数の 0 から 255 までの値がランダムで設定されます。
以下のように、点数が入るたびに背景色がランダムに変わります。

今日のコードです。

float ballX, ballY;
float racketY;
int xDir, yDir;
float xSpeed, ySpeed;
float enemyY;
float easing;
int myScore = 0;
int enemyScore = 0;
int mySet = 0;
int enemySet = 0;
int r, g, b;

void setup() {
  size (480,320);
  ballX = width/2;
  ballY = height/2;
  racketY = height/2;
  easing = 0.1;
  xDir = 1;
  yDir = 1;
  xSpeed = 1;
  ySpeed = 1;
  r = 0;
  g = 0;
  b = 0;
}

void draw() {
  background(r, g, b);
  
  strokeWeight (1);
  stroke(255);
  for ( int i = 0; i < height; i += 10 ){ 
　　line(width/2, i, width/2, i+5); 
　} 
　//my racket 
　float targetY = mouseY; 
　racketY += (targetY - racketY) * easing; 
　rect(440, racketY-25, 8, 50); 

　//enemy racket 
　enemyY += (ballY - enemyY) * easing; 
　rect(40, enemyY-25, 8, 50); 
　ellipse(ballX, ballY, 6, 6); 
　if((ballY+3>height) || (ballY-3<0)) yDir *= -1; 
　if ((ballX+3 >= 440) && (ballX+3 <= 448) && (ballY > racketY-25) && (ballY < racketY+30))
    xDir *= -1;
  if ((ballX-3 <= 48) && (ballX-3 >= 40) && (ballY > enemyY-25) && (ballY < enemyY+25)) 
　　xDir *= -1; 
　if (ballX+3 > width) {
    enemyScore ++;
    ballX = width/2;
    ballY = height/2;
    xSpeed = random(1, 4);
    ySpeed = random(1, 4);
    r = int(random(256));
    g = int(random(256));
    b = int(random(256));
  }
  else if(ballX-3 < 0) { 
　　myScore ++; 
　　ballX = width/2; 
　　ballY = height/2; 
　　xSpeed = random(1, 4); 
　　ySpeed = random(1, 4); 
　　r = int(random(256)); 
　　g = int(random(256)); 
　　b = int(random(256)); 
　} 
　ballX += xSpeed * xDir; 
　ballY += ySpeed * yDir; 

　textAlign(CENTER, CENTER); 
　textSize(30); 
　text(enemySet, 80, 20); 
　text(enemyScore, 160, 20); 
　text(mySet, 320, 20); 
　text(myScore, 400, 20); 

　if (myScore > 2) {
    mySet++;
    myScore = 0;
  }
  if (enemyScore > 2) {
    enemySet++;
    enemyScore = 0;
  }
  
  xSpeed += 0.01;
  ySpeed += 0.01;
  
  textSize(80);
  if (enemySet >= 3){
    text("You LOSE!", width/2, 130);
    textSize(40);
    text("Click to restart", width/2, 200);
  }
  else if (mySet >= 3){
    text("You WIN!", width/2, height/2-30);
    textSize(40);
    text("Click to restart", width/2, height/2+30);
  }
  
  if(mousePressed){
    ballX = width/2;
    ballY = height/2;
    mySet = 0;
    myScore = 0;
    enemySet = 0;
    enemyScore = 0;
    xSpeed = 1;
    ySpeed = 1;
  }
}