A Hydra chain without `.out()` builds a texture that is never rendered — no error, just black

In Hydra, every visible chain must end with .out(oN) to route its texture to an output buffer that gets displayed. A chain that omits .out() computes a texture internally but never renders it — the canvas stays black (or shows whatever was previously drawn), with no error or warning. render() only controls which output buffers are displayed and does not substitute for .out(). This is the most common cause of a black screen in Hydra.

Examples

osc(10).out(o0) // renders to canvas osc(10) // black screen, no error render(o0) // display only, does not fix missing .out()

Assessment

A student writes osc(20).rotate(0.1) and sees a black canvas. Diagnose the problem and write the corrected one-liner.