Testing fox vbtool thing. Btw, look at the amazing Graphics: Electric Field demo

Put it all in a form, run and enjoy:

Code:

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Option Explicit
'KedamansChargesandElectricFieldDemo

' 1. mouse down where you want to have a chage
' 2. drag to set the size
' 3. hold shift down for positive chages

Const Grid! = 50 'Decrease this value (not below 15) for more more gridpoints ( _
        cool), increase to see the field lines (also cool) to 100 or 150
Const ShowCharges As Boolean = True
Const Escale! = 2000000 'Field Strength Scale Constant

Private Type P2S
        X As Single
        Y As Single
End Type
Private Type Charge
        Mag As Single
        Pos As P2S
End Type
Private Enum enmmode
        None
        DrawCharge
End Enum
Dim mode As enmmode, current As Charge, _
        charges() As Charge, chargescount As Long

Private Sub Draw()
On Error Resume Next
Dim x!, y!, n&, sumx!, sumy!, dx!, dy!, m!, q!
        Cls
        For Y = ScaleTop To ScaleTop + ScaleHeight Step Grid
                  For X = ScaleLeft To ScaleWidth Step Grid
                                sumx = 0
                                sumy = 0
                                For N = 0 To chargescount - 1
                                        With charges(N)
                                                  dx = .Pos.X - X
                                                  dy = .Pos.Y - Y
                                                  M = (dx * dx + dy * dy)
                                                  Q = Sqr(M)
                                                  If Q > 10 And M > 10 Then
                                                                sumx = sumx + dx * .Mag / (M * Q) * Escale
                                                                sumy = sumy + dy * .Mag / (M * Q) * Escale
                                                  End If
                                        End With
                                Next N
                                M = sumx * sumx + sumy * sumy
                                Q = Sqr(M)
                                'if you want you could make a function that gradiently shifts between colors
                               
                                If Q Then Line (X, Y)-Step( _
        sumx / Q * 100, sumy / Q * 100), RGB((M / 1000) And 255, _
        (M / 100) And 255, (M / 10000) And 255)
                               
                                'this is another version, doesn't look cool though, red and logaritmic
                                'If q Then Line (x, y)-Step(sumx / q * 100, sumy / q * 100), (Log(m) * 10)
                 
                                'If m < 10000000 Then Line (x, y)-Step(sumx / 10, sumy / 10), RGB((Log(m) * 2) And 255, _
        (Log(m) * 4) And 255, (Log(m) * 6) And 255)
                 
                 
                  Next X
        Next Y
        If ShowCharges Then
                  For N = 0 To chargescount - 1
                                With charges(N)
                                        FillColor = QBColor(Sgn(.Mag) * 1.5 + 2.1)
                                        Circle (.Pos.X, .Pos.Y), Abs(.Mag)
                                End With
                  Next N
        End If
End Sub

Private Sub Form_Load()
        Caption = "Kedamans Electric field and chages demo: mouse down where you want to have a chage, drag to set the size, _
        hold shift down for positive chages"
        FillStyle = vbDiagonalCross
        WindowState = vbMaximized
        'BackColor = 0
End Sub

Private Sub Form_MouseDown(Button As Integer, Shift As Integer, _
        X As Single, Y As Single)
        current.Pos.X = X
        current.Pos.Y = Y
        mode = DrawCharge
End Sub

Private Sub Form_MouseMove(Button As Integer, Shift As Integer, _
        X As Single, Y As Single)
Dim dx!, dy!
        If mode = DrawCharge Then
                  With current
                                dx = .Pos.X - X
                                dy = .Pos.Y - Y
                                FillColor = QBColor(Shift * 3 + 1)
                                Circle (.Pos.X, .Pos.Y), Sqr(dx * dx + dy * dy)
                  End With
        End If
End Sub

Private Sub Form_MouseUp(Button As Integer, Shift As Integer, _
        X As Single, Y As Single)
Dim dx!, dy!
        dx = current.Pos.X - X
        dy = current.Pos.Y - Y
        current.Mag = Sqr(dx * dx + dy * dy) * Sgn(Shift - 0.5)
        mode = None
        ReDim Preserve charges(chargescount)
        charges(chargescount) = current
        chargescount = chargescount + 1
        Draw
End Sub

Private Sub Form_Resize()
        Draw
End Sub


'Code improved by vBulletin Tool (Save as...)

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kedaman, You Rock

Very cool :)

Yep, here's another version, it doesn't display the field lines but instead a matrix of the magnitudes. The thing is that you can "dig holes" and they can be pretty cool shaped ;) Try it out, cool landscaping tool maybe?=

I liked the other one better. The new one doesnt put the holes/spikes in the right place, although it is still very cool =)

Yeah, that's cool!

And thx for testing :)
(reminds me the error when splitting comment-lines)

It also splits strings, which gives an error in kedaman's code (the first one).

Z.

Done.

Code:

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Caption = "Testing this new function to test the new-lines when using strings and " & _
        "comments. It is a useless text that I write here but it should give you the idea " & _
        "*hehe*" 'So this is a long comment originally written on one line...
        'It dont need to tell you anything about the program since it's only a test of code.

'Code improved by vBulletin Tool (Save as...)

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Phew, you're right. That looks bad :(

I made a little bugfix but I don't think I can make your ideas in this project. Just because I don't have the time ;) Best is if you disable the newline option... well I planned to make a new version from the beginning as soon as I got more time.

(You can set the indenting since 1.0.12, see options)

However, to colorize code it works fine ^_^

Damnit Kidman you make me sick. You are just to damn good at this stuff. I think you and Megatron should just go live on an island somewhere making some cool software for us. :D

kedaman, cool man! Are you an expert in math & physic huh... :)

Fox, juz wanna to know what does the vbBulletin Tools do?

you are simply the best

It formats the code as shown above. (adds color tags, upper-cases keywords and some other options)

Ok i turned of the auto wrapping thing, and now it shows as it should.

Now the previous versions wasn't really why i made this app at all, they look cool but that wasn't the point. The point was to show how the electric field lines are going, and i think the one i edited above was the best version of it. Have a look at that one too ;)

The guts behind isn't that complicates as you may think. Electric field is basically a vector:
Ê=sumof(k*Q_i/r^2_i*r^_i)
where Q_i is each charge and r^_i is the base vector to it
which is applied in nested loops over a specified grid on the form.

Fox, Juz try out the vBulletin Tool. it cool and if it can have a bigger Editor screen will be better still :))

I'll remember that for further versions, thx.