Translation from old basic program

From: nicolas cellier <[hidden email]>
Subject: [Newbies] Re: Translation from old basic program
To: [hidden email]
Date: Sunday, July 4, 2010, 1:40 PM

kirand <kirandev <at> ukr.net> writes:

>
> Hi!
>
> Is anybody remember basic?
>
> I am a beginner and cant understand how to make this program in Smalltalk. I
> found it in old magazine from 80-th years :)
> So, this is the program. It makes interest graphics.
>
> 10 INPUT "Enter a number"; N
> 20 DIM X(N), Y(N)
> 30 R = 120
> 40 DT = 2 * 3,1416 /N
> 50 T = 0
> 60 FOR I = 1 TO N
> 70 T = T + DT
> 80 X(I) = 160 + R*COS (T): Y(I) = 125 - R*SIN (T)
> 90 NEXT I
> 95 CLSZ
> 100 FOR I = 1 TO N-1
> 110 FOR J= I+1 TO N
> 120 PLOT X(I), Y(I), 3
> 130 LINE X(J), Y(J)
> 140 NEXT J
> 150 NEXT I
> 160 STOP
>
> Some remarks can help. PLOT+LINE is BitBlt>>drawFrom:to:. DIM X(N), Y(N) is
> PointArray instance.
>
> If anobody make it pls give me a code to see how.
>

First attempt: draw directly on Display

| n xy r dt brush |
n := FillInTheBlank request: 'Enter a number' initialAnswer: ''.
n := Number readFrom: n.  "Transform the String into a Number"
xy := Array new: n.
dt := Float twoPi / n.
r := 120.
1 to: n do: [:i |
    "Mind the order or operations here, Smalltalk interprets left to right"
    xy at: i put: ((i*dt) cos * r +160) @ ((i*dt) sin negated * r + 125)].
brush := Form extent: 3 @ 3.
brush fillBlack.
1 to: n-1 do: [:i |
i+1 to: n do: [:j |
    Display
        drawLine: brush
        from: (xy at: i)
        to: (xy at: j)
        clippingBox: Display boundingBox
        rule: Form paint
        fillColor: nil]].

Second attempt: draw on a Form, copy the Form on Display,
restore the Display after 10 seconds.

| n xy r dt form brush |
n := (FillInTheBlank request: 'Enter a number' initialAnswer: '') asNumber.
dt := Float twoPi / n.
r := 120.
xy := (1 to: n) collect: [:i |
    ((i*dt) cos * r +160) @ ((i*dt) sin negated * r + 125)].
form := Form extent: 300@300.
brush := Form extent: 1 @ 1.
brush fillBlack.
1 to: n-1 do: [:i |
i+1 to: n do: [:j |
    form
        drawLine: brush
        from: (xy at: i)
        to: (xy at: j)
        clippingBox: form boundingBox
        rule: Form paint
        fillColor: nil]].
form displayOn: Display.
[(Delay forSeconds: 10) wait. Display restore] fork

Nicolas

Hi kirand, Hi Nicolas

Thought I'd give it a quick try. Here we just make a polygon and allow it to open. Heavily used the underlying goal of the problem to guide what is being done. I had fun seeing how easily I could do this in squeak. I have no idea if it meets the original purpose of the request.

If I really was feeling lazy I would have invented a Number fromUser method to simplify the input. I half expected someone to already have done so.

Lazy mans method:

n := (FillInTheBlank request: 'Enter a number' initialAnswer: '') asNumber.
(plottingPoints :=
(0 to: 360 by:  360 /n) collect: [ :each | (Point r: 120 degrees: each) + (160@125)  ] ) .

(LineMorph initializedInstance setVertices: plottingPoints )
openInWorld .


Yours in curiosity and service, --Jerome Peace


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