Add a 3d graphics object to a tachyon scene

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I'm trying to understand how to add 3d graphics objects to a tachyon scene.

Suppose I define a tachyon scene

sage: s = Tachyon(xres=512,yres=512, camera_center=(3,0.3,0))

and I define a torus and a 3d plot

sage: from sage.plot.plot3d.shapes import Torus
sage: t = Torus(0.5, 0.2)
sage: p = plot3d(lambda x, y: x^2 + y^2, (-2,2), (-2,2))

How can I add t and p to s?

I know I can do s.str() and t.tachyon() and p.tachyon() to get strings depicting s, t and p as tachyon scenes, so I could fiddle with these strings, but is there a better way?

For instance, if I have a string depicting a tachyon scene, can I turn it into a Sage tachyon scene, extract its objects, add them to another scene's objects?