Server Example: Tablecloth Pull

Overview

The tablecloth trick: three dishes stand on a cloth on a table, and a sharp pull on the cloth's edge whips it out from under them. Kinetic friction (0.3) acts on the dishes only for the fraction of a second the cloth slides under them, too briefly to take them along: they shift by about 3 cm and stay on the table. The cloth is solved together with the dishes and the table (World::setMonolithicDeformables()). Every three seconds the world starts over, and the example prints how far the dishes moved.

Target

CMake target: tablecloth_pull.

Run

./build-examples/examples/tablecloth_pull

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

Details

• The cloth is 0.8 m by 0.64 m, 41 x 33 particles weighing 0.2 kg in total, with nearly inextensible edges and a little air drag.
• The dishes are 0.6 kg cylinders, 0.14 m across. The friction coefficient is 0.3 between the cloth and both the table and the dishes, and 0.5 between the dishes and the table.
• One second into each cycle, a 60 N force pulls the cloth's edge outward and slightly down for 0.15 s.
• The scene lives in include/tablecloth_pull.hpp.