CS 110 (Introduction to Computing)

Spring 2012

Assignment #2

Due by 4:00 pm on Tuesday, February 7, 2012

Task: Design an interactive sketch depicting the horizon. The top half of the sketch will represent the sky and the bottom half the ground. The exact y-coordinate of the horizon should be a variable in your code.  Color the top and bottom of your sketch appropriately. The (variable) horizontal line through the middle of the sketch is the horizon line at which all objects appear to vanish.

As the user clicks on the sketch draw one of two types of objects. If the click occurs on the sky (above the horizon), draw clouds or something else that belongs in the sky. If the click is on the ground (below the horizon), draw rocks or something else that belongs on the ground. The size of clouds and rocks should shrink as the mouse click position approaches the horizon line. 

• Make sure that your sketch is at least 500 pixels by 500 pixels.
• When the mouse is clicked, test the mouse position in relation to the horizon to determine which object to draw.
• Your objects can be simple.  For example, clouds could be made of multiple ellipses, flowers could be made with nested colored ellipses and a green rectangle, and rocks could be made of multiple rectangles.
• You must use iteration somewhere in your drawing.  For example, you could use it to draw multiple ellipses as a single cloud and multiple rectangles as a single rock.  Or, each mouse press could draw a small cluster of objects.
• Your code should use variables as appropriate.
• The size of the objects drawn must shrink as they approach the horizon to give the appearance of perspective.
• Include proper sketch source code header and adequate comments. (See Assignment Submission Policy).

Use the following structure for your program.

// Header comments
// Declare variables

void setup() {
  // Set up the drawing.
  // Draw the sky and the ground
}

void draw() { /* remains empty */ }

void mousePressed() {
  // Use the mouseY position to decide whether drawing on sky or on ground
  // Compute scale factor and call appropriate drawing function.
}

// You may rename this function, depending on what you choose as your sky object
void drawCloud( int x, int y, float scal ) {
  // Draw a cloud at the given coordinates using scale factor.
}

// You may rename this function, depending on what you choose as your sky object
void drawRock( int x, int y, float scal ) {
  // Draw a rock at the given coordinates using scale factor.
}

Requirements:

• Properly drawn horizon (sky and ground).
• The y-coordinate location of the horizon should be a variable. If the variable value changes, the program should continue to follow the rules.
• On mousePressed, objects are drawn at mouse location. If location is in the sky, one type of object is drawn. If location is on the ground, another type of object is drawn.
• As the position approaches the horizon, the objects get smaller, giving the illusion of perspective.
• Iteration (for-loop or while-loop) used somewhere in the assignment.
• Variables used appropriately in the remainder of the assignment.
• Includes proper header and adequate comments.

Carefully read the Assignment Submission Policy for how to submit your assignment.

Optional:
If you wish, for additional points, design your program so that it scales properly regardless of the size of the sketch. In other words, compute all necessary drawing parameters based on the width and height of the sketch. Your program should run the same for any sketch size.