Java I

Jonah Warren
jonah@parsons.edu
http://a.parsons.edu/~java2004

Lab 2.3 Answers

2.3a: ALTERNATING B/W on MOUSE CLICK (METHOD 1)

boolean isWhite=true; // keeps track of whether the background is white or black, start @ white
boolean prevPress=false; // keeps track of the previous "mousePressed" value, start at false

void setup() {
  size(100,100);  // create canvas
  background(255); // make white background
}

void loop() {
  // if mousePressed has changed from false to true (i.e. that it has changed from last time, and then new value is true)
  if (mousePressed!=prevPress & mousePressed) {

    // if it is white, change it to black (both background and isWhite value)
    if (isWhite) {
      background(0);
      isWhite=false;
    }
    // if it is black, change it to white (both background and isWhite value)
    else {
      background(255);
      isWhite=true;
    }

  }
  // set the current mousePressed value to prevPress, next time around, it will be the previous value
  prevPress=mousePressed;
}

2.3a: ALTERNATING B/W on MOUSE CLICK (METHOD 2)

boolean isWhite=true; // keeps track of whether the background is white or black, start @ white

void setup() {
  size(100,100);  // create canvas
  background(255); // make white background
}

void loop() {

}

// this function gets executed when mouse is pressed... not a value being updated continously
void mousePressed() {

  // change the background to white or black, depending on isWhite
  if (isWhite) {
    background(0);
  }
  else {
   background(255);
  }

  // set isWhite to its opposite
  isWhite=!isWhite;

}

2.3b: THREE COLOR CYCLE on MOUSE CLICK (METHOD 1)

int whichColor=0; // keeps track of color, start @ white
                      // 0 is white
                      // 1 is gray
                      // 2 is black
boolean prevPress=false; // keeps track of the previous "mousePressed" value, start at false

void setup() {
  size(100,100);  // create canvas
  background(255); // make white background
}

void loop() {
  // if mousePressed has changed from false to true (i.e. that it has changed from last time, and then new value is true)
  if (mousePressed!=prevPress & mousePressed) {

    // check what whichColor is: if its 0, set background to black, if 1 then gray, if 2 then white
    if (whichColor==0) {
      background(0);
    }
    else if (whichColor==1) {
      background(127);
    }
    else {
      background(255);
    }

	// increment which whichColor (use modulo 3 to keep value either 0,1 or 2)..
    whichColor=(whichColor+1)%3;

  }
  // set the current mousePressed value to prevPress, next time around, it will be the previous value
  prevPress=mousePressed;
}

2.3b: THREE COLOR CYCLE on MOUSE CLICK (METHOD 2)

int whichColor=0; // keeps track of color, start @ white
                      // 0 is white
                      // 1 is gray
                      // 2 is black

void setup() {
  size(100,100);  // create canvas
  background(255); // make white background
}

void loop() {

}

// this function gets executed when mouse is pressed... not a value being updated continously
void mousePressed() {

  // check what whichColor is: if its 0, set background to black, if 1 then gray, if 2 then white
  if (whichColor==0) {
    background(0);
  }
  else if (whichColor==1) {
    background(127);
  }
  else {
   background(255);
  }

  // increment which whichColor (use modulo 3 to keep value either 0,1 or 2)..
  whichColor=(whichColor+1)%3;

}