Assignment 1: Plaid

Due by email before class, Monday, Jan. 24, but PREFER YOU EMAIL ME SUNDAY EVENING BY 9PM

Starting Point

In class we barely got to the following program. It has a point going up and to the right. When it gets to an edge, the point continues its motion at the opposite edge. Here is what we had (start with this):

final int WIDTH = 640;
final int HEIGHT = 350;
final int WHITE = 255;
final int BLACK = 0;

int position_x;
int position_y;

void setup() {
  size(640, 350); // Stylistically, this should be size(WIDTH, HEIGHT).
  background(WHITE);
  position_x = WIDTH / 2;
  position_y = HEIGHT / 2;
}

void draw() {
  position_x = position_x + 1;
  position_y = position_y - 1;
  if (position_x >= WIDTH) {
    position_x = 0;
  }
  if (position_y < 0) {
    position_y = HEIGHT - 1;
  }
  stroke(BLACK);
  point(position_x, position_y);
}

Result

Modify this program to have four points:

• one going up and to the right (which is all the above program has)
• another going down and to the right
• another going down and to the left
• one more going up and to the left

When any of the points reaches an edge, that point should continue its motion at the opposite edge.

Hint for Getting Started

You are going to need four position_x’s and four position_y’s. How about starting by replacing

int position_x;
int position_y;

with

int position_x1;
int position_y1;
int position_x2;
int position_y2;
int position_x3;
int position_y3;
int position_x4;
int position_y4;

Extensions

As a simple extension, just find the places to swap WHITE and BLACK so that you have white rays on a black background.

As a different extension, can you figure out a way to make about making the dots get less black as the program proceeds?