visualpython-users

[Visualpython-users] Uniform scaling with gdisplay

[Poul R. <Pou...@sk...>]

How can I force gdisplay to use the same scale on both axes?

Poul Riis

Re: [Visualpython-users] Uniform scaling with gdisplay

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

You can of course specify the axis scales explicitly, so I assume you are
asking whether there is a way to permit autoscaling but force the scale
factors to be equal. No, there isn't a way to do that. However, note that
the graph module is pure VPython, so feel free to implement what you want.

Bruce Sherwood
On Oct 12, 2012 9:31 AM, "Poul Riis" <Pou...@sk...> wrote:

> ** **
> How can I force gdisplay to use the same scale on both axes?
>
> Poul Riis
>
>
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Re: [Visualpython-users] Uniform scaling with gdisplay

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

The easiest way to achieve autoscaling with x and y scales equal is to
not use graphing. Here is the basic idea:

from __future__ import division, print_function
from visual import *
scene.title = 'Spiral'
scene.width = scene.height = 800
scene.background = color.white
scene.foreground = color.black
scale = 1
xaxis = curve(pos=[(-scale,0),(scale,0)], color=color.gray(.5))
yaxis = curve(pos=[(0,-scale),(0,scale)], color=color.gray(.5))
xlabel = label(pos=(0.95*scale,-0.05*scale), text='x', box=0)
ylabel = label(pos=(0.05*scale,0.95*scale), text='y', box=0)

p = points(color=color.blue)
kr = 1
kt = 1
t = 0
dt = pi/360
while True:
    rate(1000)
    r = kr*t
    theta = kt*t
    x = r*cos(theta)
    y = r*sin(theta)
    t += dt
    m = max([x,y])
    if m > scale:
        scale = 1.05*m
        xlabel.pos = (0.95*scale,-0.05*scale)
        ylabel.pos = (0.05*scale,0.95*scale)
        xaxis.pos = [(-scale,0),(scale,0)]
        yaxis.pos = [(0,-scale),(0,scale)]
    p.append(pos=(x,y))

You could also include in the x and y labels the value of "scale".

Bruce Sherwood

Re: [Visualpython-users] Uniform scaling with gdisplay

[Poul R. <Pou...@sk...>]

This iss excellent - thank you!

Best regards,
Poul Riis



Bru...@nc... writes:
>from __future__ import division, print_function
>from visual import *
>scene.title = 'Spiral'
>scene.width = scene.height = 800
>scene.background = color.white
>scene.foreground = color.black
>scale = 1
>xaxis = curve(pos=[(-scale,0),(scale,0)], color=color.gray(.5))
>yaxis = curve(pos=[(0,-scale),(0,scale)], color=color.gray(.5))
>xlabel = label(pos=(0.95*scale,-0.05*scale), text='x', box=0)
>ylabel = label(pos=(0.05*scale,0.95*scale), text='y', box=0)
>
>p = points(color=color.blue)
>kr = 1
>kt = 1
>t = 0
>dt = pi/360
>while True:
>rate(1000)
>r = kr*t
>theta = kt*t
>x = r*cos(theta)
>y = r*sin(theta)
>t += dt
>m = max([x,y])
>if m > scale:
>scale = 1.05*m
>xlabel.pos = (0.95*scale,-0.05*scale)
>ylabel.pos = (0.05*scale,0.95*scale)
>xaxis.pos = [(-scale,0),(scale,0)]
>yaxis.pos = [(0,-scale),(0,scale)]
>p.append(pos=(x,y))