Drawing circle and sphere

[shiva kiran]

Sir,

I need to draw a circle with a given center and radius.
I want the points present in the circle with fixed angle.ex : 10 degrees.

ex :
consider center is (0,0) radius = 5;

1st point is (0,5)
2nd point is ?
.
.
.
.
I need to get the points on the circle.



question 2 :

Consider a point in space ie 3D . I need to draw a sphere for a given radius.
How to get the points.

[VBAhack]

Let me be the first to welcome you to the forums!

For question 1:

x = r*cos(θ)
y = r*sin(θ)

Use fixed increments of theta in radians.

[MaximilianMayrhofer]

Well the equation of a sphere with centre (x,y,z) is

(x' - x)^2 + (y' - y)^2 + (z' - z)^2 = r2^2

In order to get the points for a given radius, you could write a program something like this:

Private Function test()
 
Dim x As Double
Dim y As Double
Dim z As Double
Dim x0 As Double
Dim y0 As Double
Dim z0 As Double
 
Dim r As Integer
Dim i As Integer
 
Dim str As String
 
 
r = [A1].Value  'Put the desired radius in this cell before hitting F5
x0 = [A2].Value 'x-coordinate of centre
y0 = [A3].Value 'y-coordinate of centre
z0 = [A4].Value 'z-coordinate of centre
i = 1
 
For x = -r To r Step 0.5      'This will loop through every possible combination of x, y and z values within the bounds of your radius
    For y = -r To r Step 0.5  'and defined by your steps
        For z = -r To r Step 0.5
            If (x - x0) ^ 2 + (y - y0) ^ 2 + (z - z0) ^ 2 = r ^ 2 Then
                Range("B" & i) = "(" & x & "," & y & "," & z & ")"  'Outputs the coordinates to cells if they lie on the boundary of the sphere, essentially mapping the sphere
                i = i + 1
            End If
        Next
    Next
Next
 
End Function