Re: [Visualpython-users] scene width in "real" units

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

It's affected by how the user has zoomed. Here is a calculation that 
gives you what you seem to be asking for:

from visual import *
box(pos=(-5,0,0))
box(pos=(5,0,0))
show = label()
#scene.range = 100 # with this, initial label is 200 (+/-100)
while 1:
     rate(50)
     d = mag(scene.mouse.camera-scene.center)
     w = 2*d*tan(0.5*scene.fov)
     show.text = "%.1f" % w

Bruce Sherwood

Joe Heafner wrote:
>> Is there a way, e.g. a function, to return the width of a VPython 
>> scene in real life units independent of what's displayed in the scene? 
>> For example, if I'm modeling Sun and Earth and I have them on opposite 
>> sides of a scene, can I obtain the scene's width (~ 1.5e11 m) with a 
>> function call? scene.width gives the width in pixels. I'm trying to 
>> take the drudgery out of manually calculating scale factors for 
>> displaying arrows.
>>
>> Joe Heafner