Curl Field

Every particle is four floats in a single storage buffer, advected through a curl noise field. Curl noise is the perpendicular of a noise gradient, and a perpendicular field has zero divergence, so the particles circulate indefinitely instead of draining into sinks. The compute pass rewrites the buffer in place and the render pass reads the same memory as instance data, so nothing travels back to the CPU. Move the pointer and they fall toward it.