gradation

size(400,400);

​

background(0);

​

for(int y=0; y<=400; y+=5) {  

 for(int x=0; x<=400; x+=5) {    

  noStroke();

  fill(x,x,y);

  ellipse(x,y,5,5 );

  ellipse(x,y,5,5 );

 }

}

​

for(int y=0; y<=400; y+=10) {  

 for(int x=0; x<=400; x+=10) {    

  stroke(255-x,0,y);

  strokeWeight(1);

  line(x,x,x,200);

  stroke(0,x,y);

  line(y,y,200,y);

 stroke(255-x,0,y);

 line(x,400-x,x,200);

 stroke(0,x,y);

 line(400-y,y,200,y);

 }

}

​

for(int y=0; y<=400; y+=10) {  

 for(int x=0; x<=400; x+=10) {    

  stroke(255-x,0,y);

  strokeWeight(1);

  line(200,x,x,200);

  stroke(0,x,y);

  line(y,200,200,400-y);

 }

}

​

​

​

​