Target peak height (meters) at the splat center. The sim pulls
h_cur toward amplitude · env(r) at a fixed rate, so a stationary
source asymptotes at this height rather than blowing up. Wave
propagation + decay then radiate the splat outward as the source
moves. Typical boats ≈ 0.3-1.0 m.
Radius of the Gaussian envelope (meters).
World XZ center of the disturbance.