On Sep 23, 2006, at 7:08 PM, CV wrote:
On Sep 23, 2006, at 12:09 PM, lveillette wrote:
Let's say I have 3 points, x1,y1(0,0) x2,y2(10,10) and x3y3
(20,0) and I
want to draw a curve going from x1,y1 to x3,y3 and pssing thru
x2,2...
I tried using the curveShape and x2,y2 as a control point but my
line passes
somewhere bewteen y1 and y2
Does someone know how to achive what I would like to do?
I'm not sure I'd use CurveShape for fitting a curve to points, but
if I did I'd break it into two CurveShapes, one between x1,y1 and
x2, y2 and the other between x2, y2 and x3, y3. Then add suitable
control point(s) for each CurveShape, locating them in a way that
would pull things into the type of curve fit that you have in mind.
I would see some trial and error here, but maybe I'm missing
something with respect to using CurveShapes for this.
On reflection, a three point example like yours above only requires
one CurveShape. So scratch that part of my answer above. Below is an
example, which draws three points and then draws the CurveShape.
Nontheless, I would do this type of problem by fitting a polynomial
to the three given points and plotting it using Pixel(x,y). That is
straightforward and precise and doesn't raise the issue of placing a
control point. If an Object2D is wanted, I'd plot into a picture and
fold it into a PixMapShape.
Best regards,
Jack
Sub Paint(g As Graphics)
'Draw three points: (0,0), (30,30), (60,0) in cartesian coordinates
dim Points() as OvalShape
dim i as integer
For i = 0 to 2
Points.Append new OvalShape
Points(i).Width = 4
Points(i).Height = 4
Next
'The coordinates below result from y-downward and translation of
origin to X-midpoint of CurveShape
Points(0).X = -30
Points(0).Y = 0
g.DrawObject Points(0), 100, 100
Points(1).X = 0
Points(1).Y = -30
g.DrawObject Points(1), 100, 100
Points(2).X = 30
Points(2).Y = 0
g.DrawObject Points(2), 100, 100
'Now draw a CurveShape through the three points
dim c as New CurveShape
c.X = -30
c.Y = 0
c.X2 = 30
c.Y2 = 0
c.Order = 1
c.ControlX(0) = 0
c.ControlY(0) = -60 // eyeball this
g.DrawObject c, 100, 100
End Sub
_______________________________________________
Unsubscribe or switch delivery mode:
<http://www.realsoftware.com/support/listmanager/>
Search the archives of this list here:
<http://support.realsoftware.com/listarchives/lists.html>
