C++ controllers

Unlike Python, C and C++ controllers must be compiled before running them. Every example in this documentation has a C/C++ tab with the same program as the Python one, and all of them were compiled and run on the starter robot.

Tip

In C++, get devices with typed functions, like robot->getMotor("left wheel motor") or robot->getCamera("camera"), instead of getDevice(). Include the matching header, like <webots/Motor.hpp>.

A first program

#include <cmath>
#include <webots/Robot.hpp>
#include <webots/Motor.hpp>

using namespace webots;

int main() {
  Robot *robot = new Robot();
  int timeStep = (int)robot->getBasicTimeStep();

  Motor *left = robot->getMotor("left wheel motor");
  Motor *right = robot->getMotor("right wheel motor");
  left->setPosition(INFINITY);
  right->setPosition(INFINITY);
  left->setVelocity(3.0);
  right->setVelocity(3.0);

  while (robot->step(timeStep) != -1) {
  }

  delete robot;
  return 0;
}

Compiling

The easiest way on any system is the Webots editor: use Wizards > New Robot Controller to create a C++ controller with its Makefile, and press the Build button. See the Webots guide.

You can also compile from a terminal. This command was tested on macOS:

WEBOTS=/Applications/Webots.app/Contents
clang++ -std=c++17 -I$WEBOTS/include/controller/cpp -L$WEBOTS/lib/controller \
  -lController -lCppController -Wl,-rpath,$WEBOTS/lib/controller \
  my_controller.cpp -o my_controller

On Linux, the same options work with WEBOTS=/usr/local/webots. If you use OpenCV, add its options too. With OpenCV 4 installed, for example with Homebrew on macOS, $(pkg-config --cflags --libs opencv4) gives them. The examples were tested with OpenCV 4.13.

Running

• On Windows, load the .exe file with the left LOAD button of the control window.
• On macOS and Linux, compiled programs have no file extension, and the LOAD button cannot select them. Run them with the Remote Controller instead, as you would at a competition.