So I'm working on building and creating an interactive 2D world. I want the user to be able to move his cursor to the edge of the screen and scroll the world, as in the manner of a side scroller.

How do I go about this? Are there any libraries that are needed for something like this? Right now, I have a world composed of array objects that are displayed as blocks, as well as numerous other object classes that are displayed. How do I scroll the screen?

Thanks!

So I'm making a game where I want a turret object to be able to choose between a random set of targets. The targets are several arrays of similar objects (for example, 5 scout craft, 2 light fighters, 3 heavy cruisers). Once a target is chosen, the turret then fires its weapon at the target at its firing rate. Any suggestion for the best way to go about doing this?

1. class Turret {
     float xPos, yPos;
     float accuracy, hull, dr, shield;
     int firingRate, fire;
     float xSize, ySize;
     boolean isClicked, noTarget;
     String name;
     // turrets can display, but cannot move
     void display() {
       //rectMode(CENTER);
       fill(255);
       rect(xPos, yPos, xSize, ySize);
       strokeWeight(3);
       stroke(255);
       noFill();
       ellipse(xPos+xSize/2, yPos+ySize/2, xSize*2, ySize*2);
       strokeWeight(1);
       stroke(0);
     }
   
     void displayHUD() {
       if (isClicked==true && hud.isOn==true) {
         textFont(smallText);
         fill(255, 100, 100);
         text(hull, 80, 18);
         text(accuracy*100+"%", 100, 36);
         text(firingRate/30+"/second", 120, 54);
         text(name, width/2, 36);
         fill(0);
         textFont(font);
       }
     }
   
     // turrets can take damage
     void takeDamage(int dmg) {
       // Turrets are immobile targets. However, they can be upgraded with shields and DR, later.
       // 1d20+accuracy rating vs. 1d20+defense rating
       hull-=dmg;
     }
   
     // turrets can target enemy ships
     void targetShip() {
       if (numSS!=0) {
         int temp=int(random(numSS));
         for (int i=0; i<numSS; i++) {
           if (i==temp && noTarget==true) {
             ss[i].setTarget();
             noTarget=false;
           }
           else {
             break;
           }
         }
       }
     }
     // if focus is on this cannon, its attributes will be displayed as text
     void checkFocus() {
       if (mouseX>=xPos && mouseX <= xSize+xPos) {
         if (mouseY<=yPos+ySize && mouseY>=yPos) {
           if (isClicked==false && hud.isObjectFocused==false) {
             isClicked=true;
             hud.isObjectFocused=true;
           }
           else if (isClicked==true) {
             isClicked=false;
             hud.isObjectFocused=false;
           }
         }
       }
     }
   }
   
   class LaserTurret extends Turret {
     LaserTurret(float x, float y, float xS, float yS) {
       xPos=x;
       yPos=y;
       xSize=xS;
       ySize=yS;
       hull=100;
       accuracy=0.10;
       firingRate=60;
       name="Laser Turret";
     }
     void fireLaser() {
       if (fire==firingRate) {
         for (int i=0; i<numSS; i++) {
           boolean temp=ss[i].isTarget();
           if (temp==true) {
             l = new Laser(xPos, yPos, ss[i].xPos, ss[i].yPos);
             l.display();
             ss[i].takeDamage(accuracy, l.dmg);
             fire=0;
           } else {
           }
         }
       }
       else if (fire<firingRate) {
         fire++;
       }
     }
   }
   

1. class Ship {
   
     float xPos, yPos; // Every ship has a position on the 2D world plane. In addition, each ship has a height and width.
     int xSize, ySize;
     float hull, defense, xVector, yVector, dmgbonus, accuracy; // Every ship has a hull value, defense value, and speed values. The dmgbonus value is added in some form to the ship's weapons
     int firingRate;
     float aluminum, carbon, steel; // The materials the ship is made of and drops upon death
     boolean isClicked, isTarget;
     String name;
     // Every ship can be displayed on the screen
     void display() {
       fill(255);
       ellipse(xPos, yPos, xSize, ySize);
     }
   
     // Every ship can move. The AI of the specific ships will determine the current x vector and y vector
     void move() {
       xPos+=xVector;
       yPos+=yVector;
       if (xPos>=width) {
         xPos+=-xPos;
       }
     }
   
     // Every ship can take damage
     void takeDamage(float acc, int dmg) {
       // The attacker's accuracy rating and the defender's defense rating are rolled against each other as:
       // 1d20+accuracy rating vs. 1d20+defense rating
       float isHit=acc+random(20)-defense-random(20);
       if (isHit>0) {
         hull-=dmg;
       }
       if (hull<=0) {
         explosion(xPos, yPos, xSize, ySize);
         xPos=10000;
         yPos=10000;
       }
     }
   
     // if focus is on this ship, its attributes will be displayed as text
     void checkFocus() {
       if (mouseX>=xPos-xSize && mouseX <= xSize+xPos) {
         if (mouseY>=yPos-ySize && mouseY<=yPos+ySize) {
           if (isClicked==false && hud.isObjectFocused==false) {
             isClicked=true;
             hud.isObjectFocused=true;
           }
           else if (isClicked==true) {
             isClicked=false;
             hud.isObjectFocused=false;
           }
         }
       }
     }
   
     void setTarget() {
       isTarget=true;
     }
    
     boolean isTarget() {
       return isTarget;
     }
     // Actions that ships take will be defined in their own classes
   }
   
   // The most basic ship, and the first that you will encounter
   class ScoutShip extends Ship {
     ScoutShip(float x, float y, int h, int w) {
       xPos=x;
       yPos=y;
       xSize=h;
       ySize=w;
       hull=15;
       defense=0.05;
       xVector=4;
       yVector=0;
       dmgbonus=0;
       isClicked=false;
       name="[Class 0] Scout";
     }
   
     void AI() {
       // The most basic ship, the scoutship merely attempts to fly around randomly.
       // Several for loops will be activated by a random number, each one accelerating the craft in a random direction
     }
   
     void fireWeapon() {
       // The scoutship has no weapon
     }
    
     void displayHUD() {
       if (isClicked==true && hud.isOn==true) {
         textFont(smallText);
         fill(255, 100, 100);
         text(hull, 80, 18);
         text(accuracy*100+"%", 100, 36);
         text(firingRate/30+"/second", 120, 54);
         text(name,width/2,36);
         fill(0);
         textFont(font);
       }
     }
   }
   

Then during the draw function:

1.   //display enemy craft
     if (numSS!=0) {
       for (int i=0; i<numSS; i++) {
         ss[i].move();
         ss[i].display();
       }
     }
2. ........
   
3.   // if any exist, display the laser cannons and if they are activated fire them!
     if (numCannons!=0) {
       for (int i=0; i<numCannons; i++) {
         mL[i].display();
         mL[i].targetShip();
         mL[i].fireLaser();
       }
     }