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declarations.rkt
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declarations.rkt
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#lang racket
(require (prefix-in srfi: srfi/48))
(provide (struct-out particle) (struct-out gnode) (struct-out bbox) (struct-out vec)
theta iter g timeslice drawtime zipwith singleton sum concat lc bounding-box
display-forces display-particles display-bbox display-tree)
(define format-string "~4,3F") ;; This is what decides the output format of numbers
(define (print-formatted num) ;; This is what prints floating point numbers
(display (srfi:format format-string num)))
; A particle is a struct with a record of its mass, its location, and
; its velocity:
(struct particle (mass posn velocity) #:transparent)
;The struct representing the tree
(struct gnode (mass posn subtrees) #:transparent)
;Struct for the bounding box. Specifies the box by giving lower left x
;and y axis and upper right x and y axis values.
(struct bbox (llx lly rux ruy) #:transparent)
; struct representing the vector of a particle in 2D space.
(struct vec (x y) #:transparent)
;Global declarations
(define theta 2) ;decides which particles are deemed close to one another
(define iter 10000) ;decides number of iterations to run
(define g 18) ;gravitational constant in UniverseX
(define timeslice .01) ;the simulation is updated after unit time
(define drawtime 1) ;Draw every drawtime iterations
(define (zipwith f l1 l2)
(cond [(or (null? l1) (null? l2)) '()] ;
[else (cons (f (car l1) (car l2)) (zipwith f (cdr l1) (cdr l2)))]))
(define (singleton l) ( = (length l) 1))
(define (sum l) (foldl + 0 l))
(define (concat l) (foldr append `() l))
(define (bounding-box particles)
(define (fn-upper nextp acc) (max (vec-x nextp) (vec-y nextp) acc))
(define (fn-lower nextp acc) (min (vec-x nextp) (vec-y nextp) acc))
(let ([ur (+ 1 (foldr fn-upper -50000000 (map particle-posn particles)))]
[ll (- (foldr fn-lower 50000000 (map particle-posn particles)) 1)])
(bbox ll ll ur ur )))
(define-syntax lc
(syntax-rules (: <- @)
[(lc expr : var <- drawn-from) (map (lambda (var) expr) drawn-from)]
[(lc expr : @ guard) (if guard (list expr) `())]
[(lc expr : @ guard qualifier ...)
(append* (lc (lc expr : qualifier ...) : @ guard))]
[(lc expr : var <- drawn-from qualifier ...)
(append* (lc (lc expr : qualifier ... ) : var <- drawn-from))]))
(define (display-vec t)
(display "(")
(print-formatted (vec-x t))
(display ", ")
(print-formatted (vec-y t))
(display ")"))
(define (display-particle p)
(begin
(display "(particle: ")
(print-formatted (particle-mass p))
(display ", ")
(display-vec (particle-posn p))
(display ", ")
(display-vec (particle-velocity p))
(display ")")))
(define (display-particles ps)
(cond [(not (null? ps))
(begin
(display "[")
(display-particles-helper ps 1)
(display "]"))]))
(define (display-particles-helper ps indent)
(cond [(not (null? ps)) (begin
(printblanks indent)
(display-particle (car ps))
(newline)
(display-particles-helper (cdr ps) 2)
)]))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (display-force p)
(begin
(display "(force: ")
(display-vec p)
(display ")")))
(define (display-forces ps)
(cond [(not (null? ps))
(begin
(display "[")
(display-forces-helper ps 1)
(display "]"))]))
(define (display-forces-helper ps indent)
(cond [(not (null? ps)) (begin
(printblanks indent)
(display-force (car ps))
(newline)
(display-forces-helper (cdr ps) 2)
)]))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Each entity is placed at the begining of a line and given a certain
; indent and at the end of printing leaves the state at the begining
; of a line
(define (display-tree t)
(display-tree-helper t 0))
(define (display-tree-helper t indent)
(cond [(null? (gnode-subtrees t))
(begin
(display "(leaf ")
(print-formatted (gnode-mass t))
(display " ")
(display-vec (gnode-posn t))
(display ")"))]
[else (display "(gnode ")
(print-formatted (gnode-mass t))
(display " ")
(display-vec (gnode-posn t))
(newline)
(printblanks (+ indent 2))
(display "[")
(display-list (gnode-subtrees t) (+ indent 3))
(display "])")
]))
;
(define (display-list lt indent)
(begin
(cond [(not (null? lt))
(begin
(display-tree-helper (car lt) indent)
(cond [(not (null? (cdr lt)))
(begin
(newline)
(printblanks indent)
(display-list (cdr lt) indent))]))])))
(define (display-bbox bb)
(begin
(display "(bbox: ")
(print-formatted (bbox-llx bb))
(display " ")
(print-formatted (bbox-lly bb))
(display " ")
(print-formatted (bbox-rux bb))
(display " ")
(print-formatted (bbox-ruy bb))
(display ")")
(newline)))
(define (printblanks indent)
(cond[(not (= indent 0))
(begin
(display " ")
(printblanks (- indent 1)))]))
;(define indent 0)
;(define (display-tree t)
; (display-tree-helper t))
;
;(define (display-tree-helper t)
; (cond [(null? (gnode-subtrees t))
; (begin
; (display "(leaf ")
; (print-formatted (gnode-mass t))
; (display " ")
; (display-vec (gnode-posn t))
; (display ")"))]
; [else (display "(gnode ")
; (print-formatted (gnode-mass t))
; (display " ")
; (display-vec (gnode-posn t))
; (newline)
; (printblanks (+ indent 2))
; (display "[")
; (set! indent (+ indent 3))
; (display-list (gnode-subtrees t))
; (set! indent (- indent 3))
; (display "])")
;
; ]))
;(define (display-list lt)
; (begin
; (cond [(not (null? lt))
; (begin ;(printblanks indent)
; (display-tree-helper (car lt))
; (cond [(not (null? (cdr lt)))
; (begin
; (newline)
; (printblanks indent)
; (display-list (cdr lt)))]))])))