Due date: Monday, January 30.

Ex. 1 Download the following files in a separate folder (you don't want to mix the main.cc and the Makefile with those of another program). The name of the executable is now "illusion":
Makefile
glheader.h
interface.h
interface.cc
illusion.h
illusion.cc
main.cc

Compile and run the program. You should see the following result:

Ex. 1. Lens Illusion. Complete the function lensIllusion in the file illusion.cc to create something similar to the following image:

For this, add two loops to the function, one for horizontal lines and one for vertical lines. For example, if the control variable for the vertical loop is i, (starting from 1, incremented by 1) in each iteration you should create 2 lines similar to the ones given as example, but where the distance between the lines in the previous iteration and the new one is equal to i * gap in each iteration, both increasing from the left, and decreasing from the right. The loop should end when the new vertical lines pass the middle of the image (width/2). A symmetrical idea applies to the horizontal loop.

Ex. 2. Interface. Improve the interface of the program with the following features. You can (and should) add your own functions for the more complex operations. Don't forget to add their prototypes to the header file if necessary and to submit the header file too in that case.

• Change the title of the application window to "Lens Illusion".
  
  
• Change the default size of the window to 600 x 400.
  
  
• Add 3 more colors that you like as arrays in interface.cc. Add some functionality to the spacebar to cycle the background of the window through the colors (existing and defined by you).
  
  
• Define two global variables in interface.cc for the size of the illusion, initialize them with the size of the window, and pass them in the function call to the function lensIllusion. Then add to the function spkey two cases for the up and down (GLUT_KEY_UP and GLUT_KEY_DOWN) arrows where you increase and decrease the size of the illusion by 5. Do not let either of these values become less than 5 in the process. In other words, ignore the operation if it would result in values that are too small. This will create a sort of zoom in and out of the scene.
  
  In addition, in the function resize, also assign the values of the parameters w and h to the width and height of the illusion.
  
  
• Add a global variable in interface.cc for the parameter gap and add two more cases in the function spkey for page up and page down (GLUT_KEY_PAGE_UP and GLUT_KEY_PAGE_DOWN) where you increase and decrease the value of this variable by 1 every time. Do not decrease the value to something less than 1.
  
  
• Add two cases in the function key for the letters 'r' and 'R' where you reset the width and height of the illusion to the width and height of the window, the gap to a default value (like 5), and the color to purple.

Upload to Canvas: all the source files that you modified, to Assignments, Homework 2.