PhotonVision/photonlib-java-examples/getinrange/src/main/java/frc/robot/Robot.java

/*
 * MIT License
 *
 * Copyright (c) PhotonVision
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package frc.robot;

import edu.wpi.first.math.controller.PIDController;
import edu.wpi.first.math.util.Units;
import edu.wpi.first.wpilibj.TimedRobot;
import edu.wpi.first.wpilibj.XboxController;
import edu.wpi.first.wpilibj.drive.DifferentialDrive;
import edu.wpi.first.wpilibj.motorcontrol.PWMVictorSPX;
import org.photonvision.PhotonCamera;
import org.photonvision.PhotonUtils;

/**
 * The VM is configured to automatically run this class, and to call the functions corresponding to
 * each mode, as described in the TimedRobot documentation. If you change the name of this class or
 * the package after creating this project, you must also update the build.gradle file in the
 * project.
 */
public class Robot extends TimedRobot {
    // Constants such as camera and target height stored. Change per robot and goal!
    final double CAMERA_HEIGHT_METERS = Units.inchesToMeters(24);
    final double TARGET_HEIGHT_METERS = Units.feetToMeters(5);

    // Angle between horizontal and the camera.
    final double CAMERA_PITCH_RADIANS = Units.degreesToRadians(0);

    // How far from the target we want to be
    final double GOAL_RANGE_METERS = Units.feetToMeters(3);

    // Change this to match the name of your camera
    PhotonCamera camera = new PhotonCamera("photonvision");

    // PID constants should be tuned per robot
    final double P_GAIN = 0.1;
    final double D_GAIN = 0.0;
    PIDController controller = new PIDController(P_GAIN, 0, D_GAIN);

    XboxController xboxController;

    // Drive motors
    PWMVictorSPX leftMotor = new PWMVictorSPX(0);
    PWMVictorSPX rightMotor = new PWMVictorSPX(1);
    DifferentialDrive drive = new DifferentialDrive(leftMotor, rightMotor);

    @Override
    public void robotInit() {
        xboxController = new XboxController(0);
    }

    @Override
    public void teleopPeriodic() {
        double forwardSpeed;
        double rotationSpeed = xboxController.getLeftX();

        if (xboxController.getAButton()) {
            // Vision-alignment mode
            // Query the latest result from PhotonVision
            var result = camera.getLatestResult();

            if (result.hasTargets()) {
                // First calculate range
                double range =
                        PhotonUtils.calculateDistanceToTargetMeters(
                                CAMERA_HEIGHT_METERS,
                                TARGET_HEIGHT_METERS,
                                CAMERA_PITCH_RADIANS,
                                Units.degreesToRadians(result.getBestTarget().getPitch()));

                // Use this range as the measurement we give to the PID controller.
                // -1.0 required to ensure positive PID controller effort _increases_ range
                forwardSpeed = -controller.calculate(range, GOAL_RANGE_METERS);
            } else {
                // If we have no targets, stay still.
                forwardSpeed = 0;
            }
        } else {
            // Manual Driver Mode
            forwardSpeed = -xboxController.getRightY();
        }

        // Use our forward/turn speeds to control the drivetrain
        drive.arcadeDrive(forwardSpeed, rotationSpeed);
    }
}