Re: [Visualpython-users] how to draw lines, 2D and 3D

[Bruce S. <Bru...@nc...>]

See the curve object; just give starting and ending locations to draw a 
line.

Bruce Sherwood

siggi wrote:
> Hi all,
>
> I am a complete newbie to VPython, but I got hooked. I
> tried the bouncing ball, enriched it with audio from
> Pygame, and the simple function plot; so little code,
> so great
> effects!
>
> My first problem: how do I draw a line from x to y? I
> know how to plot functions with VPython, such as
> x = f(x), see above
>
> but how do I plot a 2D function such as
> x = f1(x)
> y = f2(y)
> draw line between x and y?
>
> In Python it is done, e.g., like this
>
>     while theta < 75.39:
>       r = math.exp(math.cos(theta))-
>         2*math.cos(4*theta)+(math.sin(theta/12))**5
>      # convert from polar coordinates
>       x = r*math.cos(theta)
>       y = r*math.sin(theta)
>       # scale to canvas size
>       xx = (x*30) + 150
>       yy = (y*30) + 150
>       if (theta == 0.0):
>         Canvas.Line(self.canvas, xx, yy, xx, yy)
>       else:
>         Canvas.Line(self.canvas, xOld, yOld, xx, yy)
>       self.canvas.update_idletasks()
>       xOld = xx
>       yOld = yy
>       theta = theta + 0.02
>
> which, in this case, creates a butterfly curve
> (from http://www.pythonmania.de/article/pybutt.html)
>
> Unfortunately, browsing tutorials and documents on
> www.vpython.org, I could not find a "line " command.
> If there would be one, 3D "butterfly" curves
> would be possible, too.
>
> Thanks,
>
> siggi
>
>
>
>
>
>  
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