Processing: Increment a counter when midpoint of ellipses are passed - processing

Question

I've got some code that displays 10 ellipses in random locations on the screen, and a square that descends from the top of the screen to the bottom, at which point it resets back at the top. What I'm trying to do is get a counter to increment when that square passes any of the ellipses (by comparing their y-positions). However, the counter increases rapidly instead of steadily and just doesn't behave desirably in general.
Here's my draw() function. barriers[i][0] stores the x-pos, barriers[i][1] the y-pos obviously.
void draw()
{
background(255);
fill(0);
for(int i = 0; i < barriers.length; i++) {
// Draw barriers
ellipse(barriers[i][0], barriers[i][1], 50, 50);
// Did we pass a barrier? (doesn't work!)
if(y >= barriers[i][0] - 1 && y <= barriers[i][1] + 1) {
counter++;
}
}
// Draw the square
rect(x, y, 25, 25);
// Draw counter alongside square
fill(255, 0, 0);
text(counter, x + 25, y - 5);
// Reset
if(y < height) {
y+=5;
} else {
y = -25;
counter = 0;
}
}
Apologies if the solution is blindingly obvious, but I'm just not seeing the problem here...
Looking forward to some assistance.

Answer 1

Look at this section of code:
if(y >= barriers[i][0] - 1 && y <= barriers[i][1] + 1) {
counter++;
}
The draw() function fires 60 times a second, so this code will be fired 60 times per second. That means that while you're passing a barrier, the counter variable will increment 60 times per second!
Presumably you only want the counter to increase once for each barrier. There are a number of ways to do this. You could have another data structure that keeps track of whether each barrier has already been passed, and then only check barriers that haven't been passed yet. Or you could keep track of the previous positions of the square, and then use that to determine when the square starts passing a barrier.
Think about how you would do this in your head, without a computer. How do you know when the square is passing a circle? How do you, in your head, only count one for each barrier?

Answer 2

Following Kevin's advice, I was able to get it working using an array of booleans which I used to ensure I wasn't incrementing counter more than once:
Full code:
float barriers[][] = new float[10][2];
float x = 400;
float y = -25;
int counter = 0;
boolean barriersChecked[] = {false, false, false, false, false, false, false, false, false, false};
void setup()
{
size(800, 600);
genBarriers();
}
void genBarriers()
{
for (int i = 0; i < barriers.length; i++) {
barriers[i][0] = random(width);
barriers[i][1] = random(height);
}
}
void draw()
{
background(255);
fill(0);
for (int i = 0; i < barriers.length; i++) {
// Draw barriers
ellipse(barriers[i][0], barriers[i][1], 50, 50);
// Did we pass a barrier?
if (barriers[i][1] < y && !barriersChecked[i]) {
counter++;
barriersChecked[i] = true;
}
}
// Draw the square
rect(x, y, 25, 25);
// Draw counter alongside square
fill(255, 0, 0);
text(counter, x + 25, y - 5);
// Reset
if (y < height) {
y+=2;
} else {
y = -25;
genBarriers();
// Reset barriersChecked
for(int i = 0; i < barriersChecked.length; i++) {
barriersChecked[i] = false;
}
}
}
Out of curiosity, is there a more elegant (loopless) way of resetting every element in barriersChecked back to false?
Suggestions of additional improvements would also be greatly appreciated.