# Introduction¶

The websim supports 2D rigid body physics for simulation and testing support using Matter.js. It can be as simple or complex as you want to make it. We will continue to add helper functions (such as the Field, Robot, and Models modules) to make this a lot easier to do. By default the websim supports an overhead view of the robot, but you can also create a side profile of your robot as well to better simulate how end effectors interact with game pieces.

The idea is you provide a MyUserPhysics object that interacts with the simulated HAL, and modifies motors/sensors accordingly depending on the state of the simulation. An example of this would be measuring a motor moving for a set period of time, and then changing a limit switch to turn on after that period of time. This can help you do more complex simulations of your robot code without too much extra effort.

By default, the websim doesn’t modify any of your inputs/outputs without being told to do so by your code or the simulation GUI.