midpoint circle drawing

[falcore20]

Hi,

i am having trouble getting my circle centered. When i run my program it draws the circle waaay in the upper left hand corner of my window so i can't even see a circle.

How can i get it to draw around a specified origin? I have this so far.

i have a feeling the circle is being draw outside my field of view. But how can i get it so the center of the circle is somewhere on the form where i can see the whole circle?

I am using the midpoint circle algorithm.

Option Explicit
Dim radius As Integer
Dim midpoint As Integer
Dim x, y, d As Integer

Private Sub cmdDrawCircle_Click()
    radius = InputBox("Please enter the radius of the circle")
    Call MidPointcircle
    
End Sub

Private Sub CirclePoints()
    PSet (x, y)
    PSet (y, x)
    PSet (y, -x)
    PSet (x, -y)
    PSet (-x, -y)
    PSet (-y, -x)
    PSet (-y, x)
    PSet (-x, y)
End Sub

Private Sub MidPointcircle()
    
    
    x = 0
    y = radius
    d = 1 - radius
    Call CirclePoints
    Do While y > x
        If d < 0 Then
            d = d + x * 2 + 3
            x = x + 1
        Else
            d = d + (x - y) * 2 + 5
            x = x + 1
            y = y - 1
            
        End If
    Call CirclePoints
    Loop
    
    
End Sub

Private Sub Form_Load()
    DrawWidth = 1
End Sub

thanks!

[ChuckB]

Hi,
Usually you must provide some sort of offset for the center of the circle to be drawn. The fact that it is in the top-left corner (probably showing only 1/4 of a circle).

Do something like this.

'these will represent the X and Y offsets
DIM mnScreenOffsetX AS LONG
DIM mnScreenOffsetY AS LONG

'assuming you are drawing to form1
mnScreenOffsetX = form1.width / 2
mnScreenOffsetY = form1.height / 2

'now, the above points should represent the center of your form
'To draw a simple circle in the middle, you could do something like 
'this.
form1.circle (mnScreenOffsetX, mnScreenOffsetY), fRadius, nColor

In your example, let's take one PSET...

PSet (x, y)

Modify it to read PSet (mnScreenOffsetX + x, mnScreenOffsetY + y)

Hope this helps.
Regards,
ChuckB

[chemicalNova]

Ah,

a drawing problem. I had this. But it is because u need to do one more line of code.

Me.Show


That is probably all u needed to do. Just use things like this for it to be easier;

Private Sub DrawCircle_Click()
Dim radius As Integer
radius = InputBox("Please Enter the radius of the circle")
Me.Show
Me.CurrentX = 1300 'The horizontal coordinate of the form
Me.CurrentY = 1300 'The vertical coordinate of the form
Me.Circle (Me.CurrentX, Me.CurrentY), radius
End Sub

Hope this helped

[dafhi]

Scale(-100, 100) - (-100, 100)