🐢 B4XTurtle - Library for teachers and parents

[inakigarm]

Is it "normal" that if turtle draws outside canva's pane the results are like that?
If the radius is high, the turtle continue to draw from side's canvas (It seems that should be better not to draw outside the pane and not continue from the other sides of the canvas)

 

[Erel]

Good job Ilan!

 

[Erel]

Is it "normal" that if turtle draws outside canva's pane the results are like that?

Yes. The drawing continues on the other side. This is how classic Logo works.

 

[Sandman]

i am sure there is a better and shorter way

There might be a shorter way, but I can't see anything wrong with solving it like this. Looks good to me!

 

[LucaMs]

For i = 1 To 360 Turtle.MoveForward(((r*2)*cPI)/360).TurnLeft(1) Next

Why calculate 360 times the "fixed" value: (r*2)/cPI/360?

 

[LucaMs]

i am sure there is a better and shorter way

I did it differently because I hoped to be able to make a continuous track, but I don't think it's possible; for this purpose I used the PushState and PopState methods, which allow that "effect".

I hope I haven't written too incomprehensible and illogical things ... I'm sleepy ?

 

[LucaMs]

Just Circle:

Public Const CLOCKWISE As Int = 1
Public Const COUNTERCLOCKWISE As Int = 2

' Wise - pass one of the two contants provided:
' CLOCKWISE or COUNTERCLOCKWISE.
Sub Circle (x As Float, y As Float, r As Float, Wise As Int)
    Turtle.SetX(x).SetY(y - r / 2)
   
    If Wise = CLOCKWISE Then
        Turtle.SetAngle(0)
    Else
        Turtle.SetAngle(180)
    End If
   
    Dim v As Float = (r * cPI) / 360
    For i = 1 To 360
        If Wise = CLOCKWISE Then
            Turtle.MoveForward(v).TurnRight(1)
        Else
            Turtle.MoveForward(v).TurnRight(-1)
        End If
    Next
End Sub

 

[LucaMs]

Just Circle:

 

[Erel]

Why calculate 360 times the "fixed" value: (r*2)/cPI/360?

This is a preoptimization which is not relevant unless you plan to draw millions of circles per second (in rabbit mode).

 

[LucaMs]

This is a preoptimization which is not relevant unless you plan to draw millions of circles per second (in rabbit mode).

I know (and I could see it) but it is just a good practice avoid "logical errors".

 

[ilan]

Why calculate 360 times the "fixed" value: (r*2)/cPI/360?

i also used a variable but when i posted the code i wanted it to be as short as possible. you know that's the "key" in a challenge
in real life i would use a variable and do the calculation only once.

Just Circle:

Public Const CLOCKWISE As Int = 1
Public Const COUNTERCLOCKWISE As Int = 2

' Wise - pass one of the two contants provided:
' CLOCKWISE or COUNTERCLOCKWISE.
Sub Circle (x As Float, y As Float, r As Float, Wise As Int)
    Turtle.SetX(x).SetY(y - r / 2)
 
    If Wise = CLOCKWISE Then
        Turtle.SetAngle(0)
    Else
        Turtle.SetAngle(180)
    End If
 
    Dim v As Float = (r * cPI) / 360
    For i = 1 To 360
        If Wise = CLOCKWISE Then
            Turtle.MoveForward(v).TurnRight(1)
        Else
            Turtle.MoveForward(v).TurnRight(-1)
        End If
    Next
End Sub

code is to LONG to do only a circle ?

 

[LucaMs]

I don't like "compact code", I much prefer code that is easy to read, debug, maintain and upgrade.

 

[LucaMs]

code is to LONG to do only a circle

That code, as you see, places the turtle in a precise position with respect to the center and allows you to draw both clockwise and counterclockwise. Of course, if you remove the empty lines, it may seem shorter ?

 

[ilan]

what about drawing a "fish" (our turtle) swimming on a wave?

Sub drawwave(r As Float)
    ...
End Sub

 

[LucaMs]

wave height and length.

 

[ilan]

wave height and length.

use r instead

drawwave(60)

 

[ilan]

no one with a solution?

 

[LucaMs]

no one with a solution?

I'm too sleepy. I would say two loops, the external one with a step which is then the limit of the internal loop.
Something like:

For i = 0 to AAA Step BBB
    For J = i to i + BBB - 1 ' <--- for the wave, sine curve

 

[ilan]

I'm too sleepy. I would say two loops, the external one with a step which is then the limit of the internal loop.
Something like:

For i = 0 to AAA Step BBB
    For J = i to i + BBB - 1

actually its very simple:

Sub drawwave(r As Float)
    Dim oppositedirection As Boolean = True
    Turtle.TurnRight(30)
    For i = 1 To 2000
        If oppositedirection Then Turtle.MoveForward(((r*2)*cPI)/360).TurnLeft(1) Else Turtle.MoveForward(((r*2)*cPI)/360).TurnRight(1)
        If i Mod 60 = 0 Then oppositedirection = Not(oppositedirection)
    Next
End Sub

 

[LucaMs]

(r*2)*cPI)/360

Again ?