Catchwater The Game Interactive Particle-Based Fluid Simulation Modeling Water Flow Through Pipes Ken Brooks and Brian Clipp May 9, 2006

The Game

Demonstration

Pipe Section Modeling

Sliced Cylinders

Catchers  Square at top, round at bottom  Interpolate in 4 strips per edge

Modeling the Structure  24 possible orientations of a pipe  How do its connectors connect?  Solution: Have a unit vector for each connector Have a unit vector for each connector Keep a quaternion per pipe Keep a quaternion per pipe Maintained as user rotates while placing Maintained as user rotates while placing Multiply by that quaternion for true direction Multiply by that quaternion for true direction

Pipe connector data  Tee 0, 1, 0 (up connector) 0, 1, 0 (up connector) 1, 0, 0 (right connector) 1, 0, 0 (right connector) 0, -1, 0 (down connector) 0, -1, 0 (down connector)

Smoothed Particle Hydrodynamics

Fluid Dynamics Conservation of Mass Conservation of Momentum Particle Accelerations

Pressure, Visosity and Surface Tension Forces Particle Density Calculation Pressure Force Calculation Viscosity Force Calculation Color Field Surface Tension Force

From Particles to Pipes  Particle simulation is inefficient for horizontal flow  Capture and count particles at inflow  Generate particles at outflow

User Interface Experience  Particle simulation is beautiful!  Free viewpoint movement is vital  ESDFWR are effective rotation controls  Not very satisfactory position controls