Code
int sqWidth = 20; // dims of the square
// row stuff
int y = 0; // row
// colors
float R = 0;
float G = 0;
float B = 0;
//SETUP
void setup() {
size(400,400);
}
void draw() {
for (int rowNum=0; rowNum < height; rowNum+=sqWidth) {
y=rowNum;
for (int sqStart=0; sqStart < width; sqStart+=sqWidth) {
noStroke();
// pick some random colors
R = random(0,255);
G = random(0,255);
B = random(0,255);
fill(R,G,B);
rect(sqStart,y,sqWidth,y+sqWidth);
}
}
}