Pointer Trail Emitter

Build the emitter yourself when the trail's density has to respond to how fast the hand is moving.

Reach for add-shader-cursor-trail or shaders-cursor-ripples when you want the packaged WebGPU looks from the Shaders library. Reach for reveal-hover-effect when the cursor exposes a second image through a mask. Reach for ambient-section-particles when motes fill a section and the pointer only disturbs them. Reach for this when the pointer lays them.

The bundled demo keeps the stage intentionally neutral. A plain dark field makes spacing, scatter, and coast easy to judge without a background image competing with the trail. The wisps are dependency-free Vanilla JavaScript rendered through the Canvas 2D API; CSS styles the interface only. There are no shaders, WebGL, or Three.js. Keep the live canvas separate from the interface so the emitter stays testable rather than baked into a composition.

Emit by distance, not by time

This is the whole mechanism. Accumulate the distance the emitter has moved and spend it in fixed steps: