CS 5010: Problem Set 11

Out: Monday, April 4, 2016

Due: Monday, April 11, 2016 at 5pm.

The goal of this problem set is to give you experience with inheritance and the model-view-controller architecture.

For this problem, you will re-factor your solution for Problem Set 10 to use inheritance whenever that would simplify your design and minimize repeated code. You will also add some controls to the launcher, and should use the MVC pattern in that part of your program. (You do not have to rewrite your entire program to use the MVC pattern, although you may do that if you wish.)

Otherwise, the deliverables and instructions for this problem set are the same as for Problem Sets 09-10. As always, you must follow the design recipe, in this case the OO Design Recipe and deliverables as spelled out in Lesson 9.5 and in deliverables.html. Be sure to sync your work and fill out a Work Session Report at the end of every work session. Use the Work Session Report for PS 11.

As with problem set 10, you may submit your solution in multiple files. Your solution must include files named simulator-3.rkt, StatefulWorld.rkt, and extras.rkt.

1. (simulator-3)
   The prospective client wants you to improve the simulator you wrote for Problem Set 10 by using inheritance. The client also wants you to add a couple of new features that will allow a user of the simulator to change the position of the launcher more easily and to change the initial velocity of DAGRs and SAGRs; the client insists these new features be added using the MVC pattern.

   Your program must include a file named simulator-3.rkt that provides exactly the same list of functions and interfaces as before, and passes all black-box tests for Problem Set 10, but adds the following behaviors:

   • The launcher can be selected by pressing the mouse button within ten pixels of the launcher's current location. (This MouseEvent might select one or more goofballs as well.)
   • Once selected, the launcher can be dragged up or down the right side of the arena by a smooth drag, so long as the mouse does not leave the rightmost quarter of the arena. If the x coordinate of a "drag" lies within the rightmost quarter of the arena, then the y coordinate of a "drag" event that occurs while the launcher is selected becomes the new y coordinate of the launcher; the launcher's x coordinate cannot be changed by a smooth drag. If the x coordinate of a "drag" lies outside the rightmost quarter of the arena, then the launcher does not move and becomes unselected. (Dragging the launcher may drag selected goofballs as well. Dragged goofballs may remain selected even if the launcher becomes unselected.)
   • Releasing the mouse button unselects the launcher without moving the launcher further.
   • The direction and speed at which DAGRs are launched starts out the same as in Problem Sets 09 and 10, but can be changed using the graphical controller described below. As in Problem Sets 09 and 10, however, the velocity of a DAGR never changes once it has been launched.
   • Typing "t" pops up a graphical controller for the initial velocity of DAGRs.
   • This graphical controller is displayed as an outline yellow semicircle of radius 100 pixels with the launcher's current location as its center. The portion of the arena that lies beneath the semicircle and its interior will not be displayed while the graphical controller is visible. (This can be accomplished by drawing the arena normally and then painting the graphical controller on top of the arena using opaque white and yellow.) Any "button-down" events whose mouse coordinates lie on or within the yellow semicircle will not affect any goofballs that lie underneath the graphical controller.
   • The initial velocity (vx, vy) acquired by newly launched DAGRs is displayed as a thin yellow line extending from the current location of the launcher to a point that's offset from that location by 10 * vx pixels in the horizontal direction and 10 * vy pixels in the vertical direction. The end of that line is highlighted by a solid yellow circle with a radius of 8 pixels. At first, therefore, the center of the solid yellow circle will be 50 pixels to the left of the launcher and 30 pixels above, reflecting the (-5,-3) pixel per tick velocity of newly launched DAGRs.
   • That solid yellow circle can be selected, dragged, and unselected using the mouse. The center of that circle cannot be dragged outside the larger yellow semicircle, and cannot be dragged to any position whose x and y coordinates are both 5 pixels or less from the x and y coordinates of the launcher. Any attempt to drag the solid circle to a forbidden position leaves the circle at its previous position until the mouse is moved to an unforbidden position or is released.
   • When a "button-up" event unselects the solid circle, the graphical controller disappears from the screen, and the x and y coordinates of the solid yellow circle's last position are converted into velocity components vx and vy by subtracting the corresponding coordinates of the launcher, dividing by 10, and rounding to the nearest integer (with rounding to even in case of a tie). If the launcher is at position (800,500), for example, and the solid yellow circle is dragged to position (755,498), then newly launched DAGRs will have an initial velocity of (-4,0).