Summary CPSC 110 PSET 3 SOLUTIONS - 2022

;; The first three lines of this file were inserted by DrRacket. They record
metadata
;; about the language level of this file in a form that our tools can easily
process.
#reader(lib "htdp-beginner-reader.ss" "lang")((modname pset-03-solution) (read-
case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-
decimal #f #t none #f () #t)))
;; DO NOT PUT ANYTHING PERSONALLY IDENTIFYING BEYOND YOUR CWL IN THIS FILE.
;; YOUR CWLs WILL BE SUFFICIENT TO IDENTIFY YOU AND, IF YOU HAVE ONE, YOUR
;; PARTNER.
;;

(require 2htdp/image)
(require 2htdp/universe)
(require spd/tags)

(@assignment psets/pset-03);Do not edit or remove this tag

;; Bounce a single ball around the screen.

;; IMPORTANT:
;; This problem set will form the basis for problem sets 4 and 5 as well.
;; You are strongly advised to put in the effort to do well on this
;; problem set so that you then have an easier time with problem sets
;; 4 and 5.
;;

;; For this problem set you must complete the design of a world program.
;; The complete program must have the following behaviour:
;; - there is a green background, with a single white ball
;; bouncing around inside that box
;; - when the ball hits the top/right/bottom/left of the box it
;; bounces in the usual way a ball would bounce off of a wall
;; - clicking the mouse replaces the ball with a new ball, at the
;; current mouse position, and with a small random x,y velocity
;;
;; Note that we are giving you significant help in the starter file.
;; There is a complete data design, some complete helper functions, as
;; well as a some wish list entries. You absolutely MUST
;; - not edit any of the complete design elements we give you
;; - complete the wish list entries we give you, and do so in a way
;; that is consistent with the rest of the design we give you
;; - must use the helpers we give you as part of your solution
;;
;; We recommend that you begin by first going through the entire file to
;; understand what is already complete and what you need to complete.
;;
(@problem 1)
(@htdw Ball)

;; Constants:
(define WIDTH 605)
(define HEIGHT 535)

(define BALL-RADIUS 10)

;;
;; Remember that [0, 100] has 101 pixels, so subtract 1 from both BOT and RIG!
;;

, (define TOP (+ 0 BALL-RADIUS)) ;these constants define the "inner box"
(define BOT (- HEIGHT BALL-RADIUS 1)) ;that constrains the center of the ball
(define LEF (+ 0 BALL-RADIUS)) ;
(define RIG (- WIDTH BALL-RADIUS 1)) ;

(define BALL (circle BALL-RADIUS "solid" "white"))

(define MTS (rectangle WIDTH HEIGHT "solid" "green"))


;; ===========================================================================
;; ===========================================================================
;; Data definitions:

(@htdd Ball)

(define-struct ball (x y dx dy))
;; Ball is (make-ball Number Number Number Number)
;; interp. (make-ball x y dx dy) is ball
;; - position x, y in screen coordinates
;; - velocity dx, dy in pixels/tick
(define B1 (make-ball (/ WIDTH 2) (/ HEIGHT 2) 4 -3))

(@dd-template-rules compound)

(define (fn-for-ball b)
(... (ball-x b)
(ball-y b)
(ball-dx b)
(ball-dy b)))


;; ===========================================================================
;; ===========================================================================
;; Functions:

(@htdf main)
(@signature Ball -> Ball)
;; start the game, call with (main B1)
;; <no tests for main functions>

(@template htdw-main)

(define (main b)
(big-bang b
(on-draw render-ball) ;Ball -> Image
(on-tick next-ball) ;Ball -> Ball
(on-mouse handle-mouse)));Ball Integer Integer MouseEvent -> Ball


(@htdf render-ball)
(@signature Ball -> Image)
;; place BALL on image at appropriate x, y coordinate
(check-expect (render-ball (make-ball 20 30 3 3))
(place-image BALL 20 30 MTS))
(check-expect (render-ball (make-ball (- WIDTH 4) (- HEIGHT 5) -2 -3))
(place-image BALL (- WIDTH 4) (- HEIGHT 5) MTS))
#;
(define (render-ball b) MTS)