The anatomy of a black hole
Whatever falls into a black hole, all that survives of it is a weight and a spin, and those two numbers fix every layer of the thing left behind.
A black hole that has settled down is described by two numbers: how heavy it is, and how fast it turns. Everything else about whatever fell in is gone. Charge would be a third, but out in space it is always zero, because anything charged pulls in the opposite sign and neutralises itself. Weight sets the size and spin sets the shape.
Working inward
Four surfaces, none of them made of anything. The horizon is where leaving stops: the surface at which every path that once led outward has tipped over to point in. Around a hole made from one collapsed star it is about the size of a large city; around the giant at the centre of the galaxy M87 it is over four times the width of Neptune’s orbit.
Outside it, on a spinning hole, is the ergosphere, where space is dragged round faster than anything can swim against it. Standing still stops being possible, though leaving does not. Further out is the photon shell, where gravity bends light into a closed circle. Furthest out is the last stable orbit: inside that one circling does not work at all, and everything between it and the horizon is falling.
Where the light comes from
Gas cannot fall straight in. It arrives with sideways motion, settles into a disc and grinds its way inward, shedding energy as light, then stops dead at the last stable orbit, because there is no orbit below that one. Whatever it has not given up by then goes down unseen.
So the last stable orbit sets the entire light budget, and spin sets the last stable orbit. A still black hole radiates about six per cent of everything it swallows. One spun as fast as a disc can drive it radiates nearly a third.
What the visualisation does
It draws all four surfaces to scale for three real black holes, one of them the giant at the centre of our own galaxy, and lets you turn the spin up. They come apart as you do: the horizon draws in, the ergosphere bulges away from it at the equator, and the single photon sphere splits in two, because light going round with the rotation is helped along and light going against it is fought. The disc and the jet arrive with the spin that drives them.
Uncharged, isolated, in equilibrium, and drawn in coordinates rather than in distances you could walk.