此代码维护刻度数,但所有方式都在新屏幕上绘制
#lang racket
(require 2htdp/universe)
(require 2htdp/image)
(define pasaulis (empty-scene 100 100))
(define (trace-circle t)
(place-image (circle 5 "solid" "blue")
(+ 50(* 40 (cos (/ t 100))))
(+ 50(* 40 (sin (/ t 100))))
pasaulis))
(define (render t)
(text (number->string t) 12 "red"))
(big-bang 1000000
(on-tick sub1 1/500)
(to-draw trace-circle)
(stop-when zero?)
(record? true))
下面的代码确实保留了图片,但我没有传递给pain处理程序的tick数 .
#lang racket
(require 2htdp/universe)
(require 2htdp/image)
(require picturing-programs)
(define (move-right-10 picture)
(beside (rectangle 10 0 "solid" "white")
picture))
(big-bang pic:calendar
(on-draw show-it 500 100)
(on-tick move-right-10 1/22))
我只是想不出来 . 如何在修改屏幕时绘制具有刻度数的绘图功能 . 大爆炸功能是否适用于此目的?
1 回答
这是一个例子: