wck_precip

worldClockKit's precipitation: rain streaks (mode 0), snowflakes (mode 1) or blown sand and dust (mode 2) from one vertex-animated mesh of drops. Each drop's seed sits in the mesh's position, its corner in the normal and a random phase in uv.x. The vertex hook moves every drop along the fall and wind velocity in world space and wraps it into a box centred on the entity (the director parks the entity on the camera each frame and writes the same point into origin), so the pattern stays fixed in the world while the camera moves through it and the cost never grows with the size of the world. density drops a share of the drops entirely, so a light shower and a downpour draw the same mesh.