I'm starting to make a game where you're supposed to be able to click to shoot and press the arrow keys to move. What I did to have the objects be able to move without having them appear to multiply, is set the playfield again before it's created. Since the playfield consists of not just a background but images and lines, I made a function called resetback in place of only calling a new background. This is the code so far (not much), at the bottom is the character's move function which doesn't work for some reason. I tried calling that movePlayer function all over the place- doesn't seem to matter.


boolean titleScreen;
boolean instructions;
boolean gameStart;

PFont font;

PImage playerRight1;
float px;
float py;
boolean lefttrue = false;

PImage football;
float footballX;
float footballY;

PImage plane;
float planeX;
float planeY;

PImage ptero;
float pteroX;
float pteroY;

PImage head;

PImage cloud43;

PImage lightbulbdx;
float lightbulbX;
float lightbulbY;
boolean bulbOn;


void setup(){
  titleScreen = true;
  instructions = false;
  gameStart = false;
  bulbOn = false;
  size(1000, 800);
  font = loadFont("Dialog-24.vlw");
 
  playerRight1 = loadImage("playerRight1.png");
 
  plane = loadImage("plane.png");
    planeX = 1000;
    planeY = 0;
  football = loadImage("football.png");
    footballX = 1000;
    footballY = 800;
  ptero = loadImage("ptero.png");
    pteroX = 0;
    pteroY = 0;
 
  head = loadImage("head.png");
 
  cloud43 = loadImage("cloud43.png");
 
  lightbulbdx = loadImage("lightbulbdx.png");
}

void draw(){
 
  px = 500;
  py = 200;
 
  if(titleScreen){
    playTitleScreen();
  }
  if(instructions){
    playInstructions();
  }
  if(gameStart){
    gamePlaying();
  }
}

void playTitleScreen(){
  background(100);
  smooth();
  textFont(font);
  fill(0);
  text("Click to start", 424, 620);
 
  if(titleScreen && mousePressed){
    titleScreen = false;
    instructions = true;
  }
}

void playInstructions(){
  background(100, 100, 255);
  smooth();
  textFont(font);
  fill(0);
  text("[Press ENTER to start]", 360, 620);
 
  if(instructions && keyCode == ENTER){
    instructions = false;
    gameStart = true;
  }
}

void gamePlaying(){
 
  resetback();
  resetlightbulb();
 
  float distractTime = second();
  if(distractTime == 0){
    planeAppear();
  }
  if(distractTime$ == 0){
    footballAppear();
  }
  if(distractTime6 == 0){
    pteroAppear();
  }
 
  if(distractTime == 0 && bulbOn == false){
    lightbulbAppear();
  }
 
  //if cloud43's x and y become > too big, cloudGameover();
 
 
  movePlayer();
 
   if(mousePressed){
   shoot();
  }

 //if(lefttrue == true){
 //pushMatrix();
 //scale(-1.0, 1.0);
 //image(playerRight1,-playerRight1.width,0);
 //popMatrix();
 //}else if(!lefttrue){
 //  image(playerRight1, px, py);
 //}
 
 
 
}
 



void resetback(){
  background(100, 100, 255);
 
  image(head, 500, 400);
 
  float cloudTime = millis();
  imageMode(CENTER);
  image(cloud43, 530, 390, 20, 20);
  image(cloud43, 535, 379, 26, 26);
  image(cloud43, 500, 390, 30+cloudTime*0.003, 30+cloudTime*0.003);
 
  noFill();
  strokeWeight(2);
  smooth();
  stroke(0);
 line(241, 150, 759, 150);
 line(241, 650, 759, 650);
 line(250, 141, 250, 659);
 line(750, 141, 750, 659);

 line(241, 200, 759, 200);
 line(241, 600, 759, 600);
 line(300, 141, 300, 659);
 line(700, 141, 700, 659);

 for(int i = 200; i < 600; i += 50){
   line(241, i+50, 309, i+50);
   line(691, i+50, 759, i+50);
 }
 for(int n = 200; n < 700; n+=50){
   line(n+50, 141, n+50, 209);
   line(n+50, 591, n+50, 659);
 }
}


void planeAppear(){
  resetback();
  image(plane, planeX, planeY);
  planeX -= 3;
  planeY += 3;
}
 
void footballAppear(){
  resetback();
  image(football, footballX, footballY);
    footballX -= 5;
    footballY -= 5;
}

void pteroAppear(){
  resetback();
    image(ptero, pteroX, pteroY);
    pteroX += 8;
    pteroY += 8;
}

void lightbulbAppear(){
  resetback();
    bulbOn = true;
    image(lightbulbdx, lightbulbX, lightbulbY);
}


void resetlightbulb(){
  bulbOn = false;
  lightbulbX = random(270, 730);
  lightbulbY = random(150, 610);
  //set these values to static?
  //noLoop();
}

void resetplane(){
    planeX = 1000;
    planeY = 0;
}
void resetfootball(){
    footballX = 1000;
    footballY = 800;
}
void resetptero(){
    pteroX = 0;
    pteroY = 0;
}


void shoot(){
   stroke(255, 0, 0, 100);
   fill(255, 60, 60);
   ellipse(mouseX, mouseY, 8, 8);
   stroke(255, 0, 0, 100);
   line(px, py, mouseX, mouseY);
}


void movePlayer(){ //This part doesn't work properly
 
  if(keyPressed && (key == CODED)){
  if(key == LEFT && px > 270){
    px -= 3;
    //lefttrue = true;
  }else if(key == RIGHT && px < 730){
    px += 3;
    //lefttrue = false;
  }else if(key == UP && py > 150){
    py -= 3;
  }else if(key == DOWN && py < 610){
    py += 3;
  }
}