Package jsim.field

Class GamePieceGripper

java.lang.Object
jsim.field.GamePieceGripper
public final class GamePieceGripper extends Object
Attaches a GamePiece to a robot body's intake point so it is carried rigidly in robot-local space each tick.

While a game piece is held, its pose and linear velocity are overridden each tick (by update()) to track the robot. The piece's physics body is not removed from the world — it just gets corrected immediately after every physics step so it always appears at the intake position.

Obtain instances from FieldSimulator.createGripper(jsim.api.SimBody, edu.wpi.first.math.geometry.Translation3d). update() is called automatically by FieldSimulator.step(), so manual calls are only needed when using the gripper with a raw SimWorld.

Example: 


 GamePieceGripper gripper = sim.createGripper(robot, new Translation3d(0.45, 0, 0.1));

 // Robot drives up to a game piece and intakes it
 gripper.grab(gamePiece);

 // ... robot drives to the speaker, then shoots ...
 gripper.eject(0, 0, 8);   launch straight up at 8 m/s

  • Method Details

    • grab

      public boolean grab(GamePiece piece)
      Attach a game piece to this gripper. The piece is immediately snapped to the intake position and its velocity is matched to the robot's.

      Returns false (no-op) if:

      • this gripper is already holding a piece, or
      • piece is already held by another gripper.
      Parameters:
      piece - the game piece to grab
      Returns:
      true if the grab succeeded

    • release

      public void release()
      Release the held piece, giving it the robot's current linear velocity. No-op if nothing is held.

    • eject

      public void eject(double vx, double vy, double vz)
      Eject the held piece with a custom world-frame velocity. Use this to model a shooter or roller that launches the piece at a specific velocity. No-op if nothing is held.
      Parameters:
      vx - ejection velocity X component (m/s)
      vy - ejection velocity Y component (m/s)
      vz - ejection velocity Z component (m/s)

    • getHeld

      public GamePiece getHeld()
      Returns:
      the currently held game piece, or null if nothing is held

    • isHolding

      public boolean isHolding()
      Returns:
      true if this gripper is currently holding a piece