图形渐变程序

Author: 北大赵前杜军 Date: 1994-02-04

        程序如下:
        ' This Program is Runing in Turbo Basic
        SCREEN 12 : CLS
        DIM Static X1(360),X2(360),Y1(360),Y2(360)
        CALL init(X1(), X2(), Y1(), Y2())
        FOR i = 0 TO 40
        FOR j = 1 TO 360
        x = (X2(j) - X1(j)) / 40 * i + X1(j)
        Y = (Y2(j) - Y1(j)) / 40 * i + Y1(j)
        x = x + 320: Y = Y + 240
        IF i = 1 THEN PSET (x, Y): bx = x: by = Y
        LINE -(x, Y)
        NEXT j
        LINE -(bx, by): delay 1: CLS
        NEXT i
        SUB init (X1(1), X2(1), Y1(1), Y2(1))
        FOR angle = 1 TO 360
        X1(angle) = 200 * COS(3.14159 * angle / 180)
        Y1(angle) = 100 * COS(3.14159 * angle / 90)
        X2(angle) = X1(angle)
        Y2(angle) = 100 * SIN(3.14159 * angle / 180)
        NEXT angle
        END SUB
        运行上述程序后,你就会看到由抛物线逐渐变化到圆的奇妙过程了。