Having random select from limited choices

Processing Coding Questions
1

Hello!

This is a pretty basic question but I haven’t found the answer yet. I’m working with some code from the loop tutorial to fill a screen with gray rectangles, each assigned a random lightness. I’ve posted my code below.

What if I wanted the program to generate the fill from a selection of only 2 or 3 colors… Something like "create rectangle with fill(255,0,0) OR fill(0,255,0)

Here’s the program right now:

float sqr = 100;

size (900,900);
background(0);
noStroke();
  
for (float y = 0; y < height; y = y + sqr) {
  for (float x = 0; x < width; x = x + sqr) {
  fill(random(255));
  rect(x, y, sqr, sqr);
  }
}

Thanks!
-Paul

1 Like
2

Welcome! Please format forum code with the </> button, or add three ticks around it. I’ll edit your post to demonstrate.

3

There are many ways to do what you want.

One simple way is to combine an array (a list of things) with a random integer (a choice about which item in the array to use).

Examples of arrays and random numbers:

…and here is a sketch combining them to pick a new random background color when you press any key.

https://editor.p5js.org/jeremydouglass/sketches/omwYbCOKw

4

You can load the three colors in an array and then you can retrieve any of these three colors by using the modulos operator (%). Since there are three colors, you can try value%3 which will return the following values depending on value: 0, 1, 2. You can use these values as the index of your color array.

int indexColor = value % colorArray.size();
color c = colorTable[indexColor];

Kf