Graphics() should work in 3d as a valid empty object

[mhampton]

From sage-support (and this has bugged me too):

I'm not sure if this is a bug or just something I'm misunderstanding, but for 2D graphics I can write code like this.

g = Graphics()
g += line( [ [-1,-1], [1,1] ] )
g.show()

But in 3D if I do either

g = Graphics()
g += sphere( (1,1,1), 2 )
g.show()

or

g = sage.plot.plot3d.base.Graphics3dGroup()
g += sphere( (1,1,1), 2 )
g.show()

I get the error:

ValueError: min() arg is an empty sequence

Is there something I'm missing on how to create a graphics object and add 3D graphics to it like the way it's done in 2D?

[wcauchois]

based on sage 4.3.1.alpha1

[wcauchois]

Robert and I confirmed this bug has been fixed in Sage 4.3. The attached patch implements a doctest for Graphics that implements this.

[timdumol]

LGTM.