可触摸的粒子图像

Read an image's pixels into a canvas and create one instanced quad per pixel whose brightness exceeds a threshold, storing its grid position and a random value as instance attributes. Maintain an offscreen canvas where the pointer path is drawn as fading radial gradients and upload it as a texture each frame. In the vertex shader, sample this touch texture at the particle's UV and push the particle outward along a random angle by that amount, plus a little noise jitter. Shade each quad with the source pixel color and a soft circular mask.