Java I

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

Lab 5

Complete the following exercises:

• Create a RolloverBlock class that has xPos, yPos (integers) and a isOver (boolean) as variables.
• Create a constructor that takes in an xPos, a yPos and sets them from parameters that are passed in.
• In the constructor, initialize isOver to false.
• Create a draw function called draw() in your class that draws a black or white block based on isOver.
• Create a function called update() that checks to see if the cursor is over the block and sets isOver appropriately.
• Create an instance of your class in the setup() function, and call your update and draw functions from the loop() function.

Code from class:

int canvasSize=200;
Car[] car = new Car[10];

void setup() {
  size(canvasSize, canvasSize);

  for(int i=0;i<10;i++) {
    car[i] = new Car(random(canvasSize), random(canvasSize), random(2.0));
  }
}

void loop() {
  background(255);

  for(int i=0;i<10;i++) {
    car[i].update();
    car[i].draw();
  }

}

class Car {

  float xPos;
  float yPos;
  float speed;

  Car(float xp, float yp, float sp) {
    xPos = xp;
    yPos = yp;
    speed = sp;
  }

  void draw() {
    rect(xPos, yPos, 25, 10);
  }

  void update() {
    xPos = xPos + speed;

    if (xPos > canvasSize) {
      xPos = 0;
    }
    else if (xPos < 0) {
      xPos = canvasSize;
    }
  }

}

Homework 5

(Please email me if you have any questions or problems)

• Look over this processing example related to objects...
• Objects
• Look out this week for an email with other reading.
• Creating your own class / objects:
  • Create a class that draws a picture of your choosing, or draws the first initial in your name.
  • Use some class variables that will affect the drawing's positioning and dimensions.
  • Create a draw function for your class, which you call from the loop function. Create an update function if you need one.
  • Have the drawing affected by either the mouseX, or mouseY or a keyboard press. Info on keyboad inputhere.
  • Create an array of these objects, and use the index of a for loop to determine the positioning of your objects.
  • Post this composition.
Here is an example of an object that responds to mouse position.


• Dynamically creating objects:
  • Use the class you created in question 1. Try and figure out how to start with a blank canvas, and the create a new drawing of the object you made in question 1 in the position where the user clicks.
  • Post this composition.
  
  
  
  • HINTS:
    • You will need to create an array of your objects - make it 100 so potentially, 100 objects can be drawn on the canvas.
    • You will need to have a variable called numObjects which is initialized to 0
    • When a mouse click happens, create a new object, with x and y appropriately initialized
    • Increment numObjects.
    • Use numObjects in your for loops somehow.
• Finish up last week's assignment if you haven't.