How to make this pattern to expand and shrink back - processing

Question

i have a task to make a pattern of circles and squares as described on photo, and i need to animate it so that all objects smoothly increase to four times the size and then shrink back to their original size and this is repeated. i tried but i cant understand problem
{
size(500,500);
background(#A5A3A3);
noFill();
rectMode(CENTER);
ellipseMode(CENTER);
}
void pattern(int a, int b)
{
boolean isShrinking = false;
for(int x = 0; x <= width; x += a){
for(int y = 0; y <= height; y += a){
stroke(#1B08FF);
ellipse(x,y,a,a);
stroke(#FF0000);
rect(x,y,a,a);
stroke(#0BFF00);
ellipse(x+25,y+25,a/2,a/2);
if (isShrinking){a -= b;}
else {a += b;}
if (a == 50 || a == 200){
isShrinking = !isShrinking ; }
}
}
}
void draw()
{
pattern(50,1);
}
this is what pattern need to look like

Answer 1

Great that you've posted your attempt.
From what you presented I can't understand the problem either. If this is an assignment, perhaps try to get more clarifications ?
If you comment you the isShrinking part of the code indeed you have an drawing similar to image you posted.
animate it so that all objects smoothly increase to four times the size and then shrink back to their original size and this is repeated
Does that simply mean scaling the whole pattern ?
If so, you can make use of the sine function (sin()) and the map() function to achieve that:
sin(), as the reference mentions, returns a value between -1 and 1 when you pass it an angle between 0 and 2 * PI (because in Processing trig. functions use radians not degrees for angles)
You can use frameCount divided by a fractional value to mimic an even increasing angle. (Even if you go around the circle multiple times (angle > 2 * PI), sin() will still return a value between -1 and 1)
map() takes a single value from one number range and maps it to another. (In your case from sin()'s result (-1,1) to the scale range (1,4)
Here's a tweaked version of your code with the above notes:
void setup()
{
size(500, 500, FX2D);
background(#A5A3A3);
noFill();
rectMode(CENTER);
ellipseMode(CENTER);
}
void pattern(int a)
{
for (int x = 0; x <= width; x += a) {
for (int y = 0; y <= height; y += a) {
stroke(#1B08FF);
ellipse(x, y, a, a);
stroke(#FF0000);
rect(x, y, a, a);
stroke(#0BFF00);
ellipse(x+25, y+25, a/2, a/2);
}
}
}
void draw()
{
// clear frame (previous drawings)
background(255);
// use the frame number as if it's an angle
float angleInRadians = frameCount * .01;
// map the sin of the frame based angle to the scale range
float sinAsScale = map(sin(angleInRadians), -1, 1, 1, 4);
// apply the scale
scale(sinAsScale);
// render the pattern (at current scale)
pattern(50);
}
(I've chosen the FX2D renderer because it's smoother in this case.
Additionally I advise in the future formatting the code. It makes it so much easier to read and it barely takes any effort (press Ctrl+T). On the long run you'll read code more than you'll write it, especially on large programs and heaving code that's easy to read will save you plenty of time and potentially headaches.)