This example is for Processing 3+. If you have a previous version, use the examples included with your software. If you see any errors or have suggestions, please let us know.

Conditionals 1.

Conditions are like questions. They allow a program to decide to take one action if the answer to a question is "true" or to do another action if the answer to the question is "false."
The questions asked within a program are always logical or relational statements. For example, if the variable 'i' is equal to zero then draw a line.

size(640, 360);

for(int i = 10; i < width; i += 10) {
  // If 'i' divides by 20 with no remainder draw 
  // the first line, else draw the second line
  if((i % 20) == 0) {
    line(i, 80, i, height/2);
  } else {
    line(i, 20, i, 180);