# Processing-Tutorial: A Grid of Arcs

In this tutorial, you’ll learn how to create a grid-based, flexible visual system of quarter circles in Processing. I’ll show you how to use the wave functions in Processing to influence the rotation of the individual grid cells.

Again, some very important concepts come together in this video: Loops, Nested Loops, Variables, Functions, Wave Movements, Conditional Statements, and Partial Circles.

At this point I would like to thank my friend Martin Lorenz, who inspired me a lot with his input on this topic. Martin will soon publish his book on Flexible Visual Systems, which I highly recommend here.

https://martinlorenz.com/

https://www.instagram.com/martinlorenz/

Enjoy the journey!

Best,

Tim

## The code

```
color bg = #000000;
color fg = #ff0000;
void setup() {
size(900, 900);
}
void draw() {
background(bg);
fill(fg);
noStroke();
float tilesX = 4;
float tilesY = tilesX;
float tileW = width / tilesX;
float tileH = height / tilesY;
for (int x = 0; x < tilesX; x++) {
for (int y = 0; y < tilesY; y++) {
float posX = tileW * x;
float posY = tileH * y;
float wave = sin(radians(frameCount + x * 10 + y * 10));
float mappedWave = map(wave,-1,1,0,5);
int selector = int(mappedWave);
pushMatrix();
translate(posX, posY);
if (selector == 0) {
arc(0, 0, tileW*2, tileH*2, radians(0), radians(90));
} else if (selector == 1) {
arc(tileW, 0, tileW*2, tileH*2, radians(90), radians(180));
} else if (selector == 2) {
arc(tileW, tileH, tileW*2, tileH*2, radians(180), radians(270));
} else if (selector == 3) {
arc(0, tileH, tileW*2, tileH*2, radians(270), radians(360));
} else {
rect(0, 0, tileW, tileH);
}
popMatrix();
}
}
}
```