Server Example: Fluid Pool

Overview

Bodies of different densities fall into a pool 4 m by 2.4 m, filled with water to 0.7 m under air (Fluids). The water holds each one up with the weight of the water it displaces, at the center of that volume.

• The ice block floats with 8 % of its height above the surface.
• The half-dense wooden cube turns an edge up: a cube of density between 0.28 and 0.72 times that of water does not float on a face.
• The raft and the log float flat.
• The hollow ball rides high. It also feels the buoyancy of the air, 6 % of its weight.
• The steel ball and the brick sink to the floor.

The waves the bodies make as they bob carry their energy away, so they settle within a few periods. Every fifteen seconds the world starts over, and the example prints how each body came to rest:

Body	Expected	Example
Ice above the water	8.1 %	7.6 % (still settling)
Wooden cube tilt	45°	42 to 45°
Raft draft	4.0 cm	4.0 cm
Steel ball over the floor	6 cm	5.9 cm

Target

CMake target: fluid_pool.

Run

./build-examples/examples/fluid_pool

Connect rayrai_tcp_viewer to port 8080. On Windows, run build-examples/bin/fluid_pool.exe.

Details

• The pool is a FluidVolume bounded by its walls, from the floor up to its surface, and the air fills the rest of the world (World::setAmbientFluid()).
• The TCP viewer draws the water of the pool: the server sends it the world's volumes of liquid.
• The scene lives in include/fluid_pool.hpp.