I would like to 'shoot' a rectangle across the screen when the mouse is pressed (kind of like the car example,  if anyone has gone throught the tutorials). Right now, I can get the rectangle across the screen while the mouse is pressed the entire time, but I'd like to just click once and have it go across...

I wasn't using the void mousePressed() method until I started looking through the forums. I've moved stuff around and at this point the rectangle isn't moving at all.

2. Bullet myBullet1;
3. Bullet myBullet2;
4. 
   
5. void setup() {
6.   size(200,200);
7.   myBullet1 = new Bullet(color(255,0,0),100,0,2);
8.   myBullet2 = new Bullet(color(200,12,20),50,0,25);
9. }
10. 
    
11. void draw() {
12.   background(255);
13.   myBullet1.display();
14. 
    
15. }
16. 
    
17. class Bullet {
18.   color c;
19.   float xpos;
20.   float ypos;
21.   float yspeed;
22.   
23.   //constructor
24.   Bullet(color tempC, float tempXpos, float tempYpos, float tempYspeed) {
25.     c = tempC;
26.     xpos = tempXpos;
27.     ypos = tempYpos;
28.     yspeed = tempYspeed;
29.   }
30.   
31.   void display() {
32.     stroke(0);
33.     fill(c);
34.     rectMode(CENTER);
35.     rect(xpos,ypos,40,10); //20,10 give width and height
36.   }
37.   
38.   void mousePressed() {
39.     shoot();
40.   }
41.   
42.     void shoot() {
43.     ypos = ypos + yspeed;
44.     if (ypos > height) {
45.       ypos = 0;
46.     }
47.   }
48. }

I've also tried the following, which get the rectangle to move only when the mouse is pressed

2. void draw() {
3.   background(255);
4.   myBullet.display();
5.   if (mousePressed) {
6.     myBullet.shoot();
7.   }
8. 
   
9. }
10. .
11. .
12. .
14.   void shoot() {
15.     ypos = ypos + yspeed;
16.     if (ypos > height) {
17.       ypos = 0;
18.     }
19.   }