Rayrai Example: Floating on Waves

Overview

Wooden crates, a raft, barrels and beach balls ride the swell of the sea. The sea of the RaiSim world (Fluids) samples the same Gerstner waves that rayrai draws, at the physics time, through FluidVolume::sampler. The water holds every body up where the drawn surface is: they heave on the crests and roll and pitch with the slope of the waves. The sampler also returns how fast the surface rises and falls, so the bodies move with the water instead of only being pushed by it. The example renders in process with raisin::RayraiWindow and does not need rayrai_tcp_viewer.

Target

CMake target: rayrai_fluid_waves (C++20).

Run

./build-examples/examples/rayrai_fluid_waves

On Windows, run rayrai_fluid_waves.exe instead. The example takes no arguments. Drag to look around and use WASD and Space to move.

Details

• The sea is rayrai's ocean with twelve Gerstner waves from 1.2 m to 16 m long (raisin::generateGerstnerWaves()). raisin::sampleWaterSurface() evaluates the same waves on the CPU, so the physics does not wait for the renderer.
• The crates are 600 kg/m³, the raft 450 kg/m³, the barrels 500 kg/m³. The beach balls weigh 0.4 kg for 0.11 m³, so they ride on top of the waves and are blown about by the slopes.
• The sea is sea water under air (World::setAmbientFluid()), and the bodies make waves of their own as they bob, which damps them.
• The scene lives in src/rayrai/physics/fluid_waves_scene.hpp.