visualpython-users

[Visualpython-users] Visibility Bug?

[Theo D. <td...@st...>]

Hello,

    I have noticed what appears to be a bug when dealing with frames and 
visibility. If I make all the objects in the frame disappear, with

             for obj in a.objects:
                      obj.visible = 0

and then attempt to make the objects reappear with
          

             for obj in a.objects:
                      obj.visible = 0

They do not appear. Is this a known, or does anyone have any 
suggestions? Presently I am overcoming this by reinstantiating the 
invisible objects, but i would like to be able to reduce the amount of 
memory this uses.

Thanks,
    Theo

Re: [Visualpython-users] Visibility Bug?

[Dunning, R. <dun...@lo...>]

Theo,

"objects" is list of all *visible* objects in the display. When you loop
over scene.objects, any objects tagged as invisible are automatically
skipped in the loop because they're not part of that list.  I'm not sure I
would call this a bug--it's how the class is coded.

I came up with the following that may do what you need.  (By the way, if you
chose to reinstantiate the non-visible objects, the memory tied up by the
former objects should be released.)


from visual import *

rate(10)

spheres = []

for i in xrange(7):
    spheres.append(sphere(pos=vector(i*3,0,0)))


scene.my_objects = spheres


for i in scene.objects:
    i.visible = 0


print "They're gone!"

print "Bring them back"

for j in scene.objects:
    j.visible = 1  # Doesn't work, as you've discovered.

print "Now try it."



for a in scene.my_objects: # This will work.
    a.visible = 1



# Hope this helps.

--
Rodney Dunning
Assistant Professor of Physics
Longwood University
http://www.longwood.edu/staff/dunningrb
 

> -----Original Message-----
> From: vis...@li... 
> [mailto:vis...@li...] On 
> Behalf Of Theo DuBose
> Sent: Wednesday, May 30, 2007 1:31 PM
> To: vpython
> Subject: [Visualpython-users] Visibility Bug?
> 
> Hello,
> 
>     I have noticed what appears to be a bug when dealing with 
> frames and visibility. If I make all the objects in the frame 
> disappear, with
> 
>              for obj in a.objects:
>                       obj.visible = 0
> 
> and then attempt to make the objects reappear with
>           
> 
>              for obj in a.objects:
>                       obj.visible = 0
> 
> They do not appear. Is this a known, or does anyone have any 
> suggestions? Presently I am overcoming this by 
> reinstantiating the invisible objects, but i would like to be 
> able to reduce the amount of memory this uses.
> 
> Thanks,
>     Theo
> 
> --------------------------------------------------------------
> -----------
> This SF.net email is sponsored by DB2 Express Download DB2 
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> 

Re: [Visualpython-users] Visibility Bug?

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

 From the Visual reference manual (on the Help manual in VPython):

------------------------
Another frame attribute is objects, which is a list of currently visible 
objects contained in the frame (the list does not include objects that 
are currently invisible). If you want to make all the objects in a frame 
be red, do the following (assume the frame is named f):

for obj in f.objects:
   obj.color = color.red

If you use this method to make all the objects invisible, the f.objects 
list will be empty. If you need a list containing all the objects, both 
visible and invisible, you need to maintain your own list of objects.
--------------------------

In the new beta version there is this new feature: "You can now make a 
frame visible or invisible, and all objects in the frame will be 
affected. And you can set the vector "scale" attribute of a frame to 
change the size of the combined object."

Bruce Sherwood

Theo DuBose wrote:
> Hello,
>
>     I have noticed what appears to be a bug when dealing with frames and 
> visibility. If I make all the objects in the frame disappear, with
>
>              for obj in a.objects:
>                       obj.visible = 0
>
> and then attempt to make the objects reappear with
>           
>
>              for obj in a.objects:
>                       obj.visible = 0
>
> They do not appear. Is this a known, or does anyone have any 
> suggestions? Presently I am overcoming this by reinstantiating the 
> invisible objects, but i would like to be able to reduce the amount of 
> memory this uses.
>
> Thanks,
>     Theo
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by DB2 Express
> Download DB2 Express C - the FREE version of DB2 express and take
> control of your XML. No limits. Just data. Click to get it now.
> http://sourceforge.net/powerbar/db2/
> _______________________________________________
> Visualpython-users mailing list
> Vis...@li...
> https://lists.sourceforge.net/lists/listinfo/visualpython-users
>   

Re: [Visualpython-users] Visibility Bug?

[Bill W. <ww...@la...>]

Hi Theo,

As Bruce and Rodney have said, it's not a bug, it's a feature!  But not one
of my favorites.  I understand the new beta will obey "frame.visible = 0" to
do what you want, but sometimes you may want to be selective, say you want
to hide only certain types of objects, so you want to turn maintain your own
list anyway.

My solution has been to write an new "Frame" subclass of "frame", and give
it methods that are convenient.  Here's that bit of code in case you find it
instructive:

class Frame(frame):
    """Subclass visual's frame to add some convenient functions.
Specifically,
    make the .visible attribute do what you expect (show or hide all the
    objects in a frame). """

    def show(self, state=None):
        """ Set visibility of all objects in the frame to 'state'.  If state
is absent,
        toggle the visibility.  Note that the .objects attribute does not
report
        hidden objects, so first a parallel list has to be created.
        """
	  #On the first call, create the all_objects list (might be cleaner
to use our own __init__()? )

        if not hasattr(self,'all_objects'): #store all objects (not just
visible)
            self.all_objects = self.objects[:]
        if state == None:
            self.visible = not self.visible
        else:
            self.visible = state
        for obj in self.all_objects:
            show(obj,self.visible)

    def animate(self, *args):
        """ Animate all the visible objects in the frame that have their own
        animate() functions defined.  Pass through everything in *args.
        """
        if self.visible:
            for o in self.objects:	#loop visible objects only
                if o and hasattr(o,'animate'):
                    o.animate(*args)

To use it:

f = Frame()
box(frame=f)
box(y=2,frame=f)
f.show(False) #make frame, a couple of objects, and hide initially

while 1:
    if scene.kb.keys: # keyboard event in main scene?
        f.show()	#toggle the objects in f on any key press

I have this class in a module of stuff I import everywhere and it tidies
things up for me a bit.  I hope it's a useful example!

Bill Ward
 
P.S.  The last "animate" function is a little distraction I left in, so let
me explain what that means briefly.  I often use a new class definition to
generate my objects, and then declare an animate() method inside that.  So
if my scene has a Frame "f" I can just call, for example, "f.animate(coswt,
sinwt)", and if all the custom moving objects in the Frame have a bound
"animate" method that expects two arguments of that form, I'm done.

Sorry to muddy things up.  You can lose that bit of code or leave it, it
should be harmless.




-----Original Message-----
From: vis...@li...
[mailto:vis...@li...] On Behalf Of Bruce
Sherwood
Sent: Wednesday, May 30, 2007 11:03 AM
Cc: vpython
Subject: Re: [Visualpython-users] Visibility Bug?

 From the Visual reference manual (on the Help manual in VPython):

------------------------
Another frame attribute is objects, which is a list of currently visible 
objects contained in the frame (the list does not include objects that 
are currently invisible). If you want to make all the objects in a frame 
be red, do the following (assume the frame is named f):

for obj in f.objects:
   obj.color = color.red

If you use this method to make all the objects invisible, the f.objects 
list will be empty. If you need a list containing all the objects, both 
visible and invisible, you need to maintain your own list of objects.
--------------------------

In the new beta version there is this new feature: "You can now make a 
frame visible or invisible, and all objects in the frame will be 
affected. And you can set the vector "scale" attribute of a frame to 
change the size of the combined object."

Bruce Sherwood

Theo DuBose wrote:
> Hello,
>
>     I have noticed what appears to be a bug when dealing with frames and 
> visibility. If I make all the objects in the frame disappear, with
>
>              for obj in a.objects:
>                       obj.visible = 0
>
> and then attempt to make the objects reappear with
>           
>
>              for obj in a.objects:
>                       obj.visible = 0
>
> They do not appear. Is this a known, or does anyone have any 
> suggestions? Presently I am overcoming this by reinstantiating the 
> invisible objects, but i would like to be able to reduce the amount of 
> memory this uses.
>
> Thanks,
>     Theo
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by DB2 Express
> Download DB2 Express C - the FREE version of DB2 express and take
> control of your XML. No limits. Just data. Click to get it now.
> http://sourceforge.net/powerbar/db2/
> _______________________________________________
> Visualpython-users mailing list
> Vis...@li...
> https://lists.sourceforge.net/lists/listinfo/visualpython-users
>   

-------------------------------------------------------------------------
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Download DB2 Express C - the FREE version of DB2 express and take
control of your XML. No limits. Just data. Click to get it now.
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_______________________________________________
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Vis...@li...
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Re: [Visualpython-users] Visibility Bug?

[Dunning, R. <dun...@lo...>]

> Hi Theo,
> 
> As Bruce and Rodney have said, it's not a bug, it's a 
> feature!  But not one of my favorites.

Just a guess: probably it was thought that programmers would find it easier
to loop over the objects in a scene (or frame) without having to explicitly
check for visibility.  Perhaps the assumption was that any loop over objects
would very likely only need to target the visible objects in the scene.

About my "fix," look at this line:

scene.my_objects = spheres

This line simply attaches the name "scene.my_objects" to the same list
referenced by "spheres."  If you later on append an object to
scene.my_objects, it gets appended to the spheres list as well (it's the
*same* list)--very likely this isn't what you want.  A classic Python
gotcha!

--
Rodney Dunning
Assistant Professor of Physics
Longwood University
http://www.longwood.edu/staff/dunningrb
 

> -----Original Message-----
> From: vis...@li... 
> [mailto:vis...@li...] On 
> Behalf Of Bill Ward
> Sent: Wednesday, May 30, 2007 2:53 PM
> To: Vis...@li...
> Subject: Re: [Visualpython-users] Visibility Bug?
> 
> Hi Theo,
> 
> As Bruce and Rodney have said, it's not a bug, it's a 
> feature!  But not one of my favorites.  I understand the new 
> beta will obey "frame.visible = 0" to do what you want, but 
> sometimes you may want to be selective, say you want to hide 
> only certain types of objects, so you want to turn maintain 
> your own list anyway.
> 
> My solution has been to write an new "Frame" subclass of 
> "frame", and give it methods that are convenient.  Here's 
> that bit of code in case you find it
> instructive:
> 
> class Frame(frame):
>     """Subclass visual's frame to add some convenient functions.
> Specifically,
>     make the .visible attribute do what you expect (show or 
> hide all the
>     objects in a frame). """
> 
>     def show(self, state=None):
>         """ Set visibility of all objects in the frame to 
> 'state'.  If state is absent,
>         toggle the visibility.  Note that the .objects 
> attribute does not report
>         hidden objects, so first a parallel list has to be created.
>         """
> 	  #On the first call, create the all_objects list 
> (might be cleaner to use our own __init__()? )
> 
>         if not hasattr(self,'all_objects'): #store all 
> objects (not just
> visible)
>             self.all_objects = self.objects[:]
>         if state == None:
>             self.visible = not self.visible
>         else:
>             self.visible = state
>         for obj in self.all_objects:
>             show(obj,self.visible)
> 
>     def animate(self, *args):
>         """ Animate all the visible objects in the frame that 
> have their own
>         animate() functions defined.  Pass through everything 
> in *args.
>         """
>         if self.visible:
>             for o in self.objects:	#loop visible objects only
>                 if o and hasattr(o,'animate'):
>                     o.animate(*args)
> 
> To use it:
> 
> f = Frame()
> box(frame=f)
> box(y=2,frame=f)
> f.show(False) #make frame, a couple of objects, and hide initially
> 
> while 1:
>     if scene.kb.keys: # keyboard event in main scene?
>         f.show()	#toggle the objects in f on any key press
> 
> I have this class in a module of stuff I import everywhere 
> and it tidies things up for me a bit.  I hope it's a useful example!
> 
> Bill Ward
>  
> P.S.  The last "animate" function is a little distraction I 
> left in, so let me explain what that means briefly.  I often 
> use a new class definition to generate my objects, and then 
> declare an animate() method inside that.  So if my scene has 
> a Frame "f" I can just call, for example, "f.animate(coswt, 
> sinwt)", and if all the custom moving objects in the Frame 
> have a bound "animate" method that expects two arguments of 
> that form, I'm done.
> 
> Sorry to muddy things up.  You can lose that bit of code or 
> leave it, it should be harmless.
> 
> 
> 
> 
> -----Original Message-----
> From: vis...@li...
> [mailto:vis...@li...] On 
> Behalf Of Bruce Sherwood
> Sent: Wednesday, May 30, 2007 11:03 AM
> Cc: vpython
> Subject: Re: [Visualpython-users] Visibility Bug?
> 
>  From the Visual reference manual (on the Help manual in VPython):
> 
> ------------------------
> Another frame attribute is objects, which is a list of 
> currently visible objects contained in the frame (the list 
> does not include objects that are currently invisible). If 
> you want to make all the objects in a frame be red, do the 
> following (assume the frame is named f):
> 
> for obj in f.objects:
>    obj.color = color.red
> 
> If you use this method to make all the objects invisible, the 
> f.objects list will be empty. If you need a list containing 
> all the objects, both visible and invisible, you need to 
> maintain your own list of objects.
> --------------------------
> 
> In the new beta version there is this new feature: "You can 
> now make a frame visible or invisible, and all objects in the 
> frame will be affected. And you can set the vector "scale" 
> attribute of a frame to change the size of the combined object."
> 
> Bruce Sherwood
> 
> Theo DuBose wrote:
> > Hello,
> >
> >     I have noticed what appears to be a bug when dealing 
> with frames 
> > and visibility. If I make all the objects in the frame 
> disappear, with
> >
> >              for obj in a.objects:
> >                       obj.visible = 0
> >
> > and then attempt to make the objects reappear with
> >           
> >
> >              for obj in a.objects:
> >                       obj.visible = 0
> >
> > They do not appear. Is this a known, or does anyone have any 
> > suggestions? Presently I am overcoming this by reinstantiating the 
> > invisible objects, but i would like to be able to reduce 
> the amount of 
> > memory this uses.
> >
> > Thanks,
> >     Theo
> >
> > 
> ----------------------------------------------------------------------
> > --- This SF.net email is sponsored by DB2 Express Download 
> DB2 Express 
> > C - the FREE version of DB2 express and take control of 
> your XML. No 
> > limits. Just data. Click to get it now.
> > http://sourceforge.net/powerbar/db2/
> > _______________________________________________
> > Visualpython-users mailing list
> > Vis...@li...
> > https://lists.sourceforge.net/lists/listinfo/visualpython-users
> >   
> 
> --------------------------------------------------------------
> -----------
> This SF.net email is sponsored by DB2 Express Download DB2 
> Express C - the FREE version of DB2 express and take control 
> of your XML. No limits. Just data. Click to get it now.
> http://sourceforge.net/powerbar/db2/
> _______________________________________________
> Visualpython-users mailing list
> Vis...@li...
> https://lists.sourceforge.net/lists/listinfo/visualpython-users
> 
> 
> 
> --------------------------------------------------------------
> -----------
> This SF.net email is sponsored by DB2 Express Download DB2 
> Express C - the FREE version of DB2 express and take control 
> of your XML. No limits. Just data. Click to get it now.
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>