between code and design

Smooth movement test

Try and compare movement types in Unity.


There are many ways to move a character in Unity. The Smooth Movement Test Application lets you play around with different settings. You can learn more about the different movement types in the blog entry.

Example of the smooth movement test application.

You can add multiple lanes with different parameters and compare the result.

Other Releases

Windows Release (Download, 18MB)

Linux Release (Download, 18MB)

Source Code on Github

Hint: The performance of the WebGL Release depends on your hardware and browser. If your running in performance issues, try a desktop release.

How to use

Add multiple lanes, set different lane settings and compare the results. Increase the ball count, enable the hinge joint option and try to find the settings which look best to you.

Move the mouse to the top center or bottom center of the canvas to move up or down. Alternatively use the Arrow Keys.

Press F to follow or unfollw the character. You can press the Arrow Keys while following to change the lane.

The Log option will print Update and FixedUpdate timings to the developer console in the browser, which can usually be opened with F12. Only enable this a short time, because a large log can slow down or even crash the browser. The desktop versions will create a log file instead called SmoothMovement.log.



Changes the target velocity of all characters, specified in Units per Second. All movement types which directly set the position or the velocity will use this exact value. The movement types AddForce, AddImpulse and AddVelocity will use a simple PID Controller which smoothly adjusts the current velocity according to deviation from the specified target velocity.


Enables or disables Vertical Sychronization of the renderer and the screen. If you enable VSync, the frame rate cannot be higher than the refresh rate of your screen. This reduces frame time variance leading to stuttering and screen tearing.

Frame Rate

By disabling VSync you will be able to set a target frame rate.

Physics Rate

This will directly set Time.fixedDeltaTime and controls how often the FixedUpdate cycle will be run.

Physics Sync

If you switch this knob to the right, you will activate manual physic updates. All characters will be moved in Update and there's no need for any kind of interpolation. Be aware that you should use movement type Custom Move instead of Move Position.


Each lane can have different lane settings. That way you can compare the smoothness of the motion and the effect of the lane settings on the balls.


You can add some "Balls" to the simulation. Spheres with a Dynamic Rigidbody2D, which will collide with the character.


Adds a HingeJoint2D component to the character with a white ball attached to it. The ball is a dynamic rigidbody with interpolation enabled. It circles around the player and is the only object affected by gravity. The hinge joint can affect the movement of the character.


Sprite shows you the position of the character which the player will see in the game, possibly interpolated. Dragging the slider will display the rigidbody position, indicated by a red sqare. This is the current position of the character used by the physic engine.


Restarts the simulation with the same settings.


This will output the information about the Update and FixedUpdate cycles. You can inspect their order and 3 values: 1) the real duration of the frame measured by System.Diagnostic.Stopwatch. 2) Time.deltaTime. 3) Time.time.

In the browser application you need to open the developer console to see the output (Press F12). In the standalone application a file will be written alongside the executable called "SmoothMovement.log".


You can specify settings per lane or all lanes can share the same settings. Shared settings are useful to measure the performance of the specified lane settings.


The camera will follow the character sprite with a yellow highlight. Press F to switch this setting on or off. You can jump through the lanes with the up and down arrow keys while following. The camera position is set in LateUpdate.


Resets all settings and restarts the simulation.


Shows the amount of Update cycles per Second, measured by a Stopwatch instance. The value is updated twice per second.


Shows (half) the difference between the smallest and longest Update cycle duration. The value is updated twice per second. A high variance value can lead to stuttering motion.

Method (Lane setting)

The movement type will either be applied in Update or FixedUpdate according to this setting. Unity advises us to use FixedUpdate for a stable physic simulation. FixedUpdate also enables the interpolation setting.

Body Type (Lane setting)

Switch between a kinematic or dynamic rigidbody used for the character. A dynamic rigidbody enables the usage of movement type AddForce and AddImpulse.

Movement (Lane setting)

Select the method used for moving the rigidbody of the character. The procedure is repeated in Update or FixedUpdate depending on the Method set above.

  • Transform.Position moves the character by setting transform.position directly.
  • Rigidbody.Position moves the character by setting Rigidbody2D.position directly.
  • Rigidbody.MovePosition moves the character by calling Rigidbody2D.MovePosition().
  • Rigidbody.CustomMove moves the character through a custom alternative to MovePosition(), which works with manual physic updates.
  • Rigidbody.SetVelocity moves the character by setting Rigidbody2D.velocity.
  • Rigidbody.AddVelocity moves the character by adjusting Rigidbody2D.velocity smoothly over time with a simple PID Controller.
  • Rigidbody.AddForce moves the character by calling Rigidbody2D.AddForce() with ForceMode2D.Force. The force is smoothly adjusted over time with a simple PID Controller.
  • Rigidbody.AddImpulse moves the character by calling Rigidbody2D.AddForce() with ForceMode2D.Impulse. The force is smoothly adjusted over time with a simple PID Controller.

Interpolation (Lane setting)

Method FixedUpdate enables you to assign an interpolation type to the character sprite.

  • None disabled interpolation. The sprite will always be at the rigidbody position.
  • Rigidbody Interpolate uses the standard Unity interpolation setting of Rigidbody2D.
  • Rigidbody Extrapolate uses the standard Unity extrapolation setting of Rigidbody2D.
  • Custom Bad uses a simple self made interpolation, which lerps the position of the sprite from the previous rigidbody position to the last calculated rigidbody position. The last calculated rigidbody position is incorrect, because it is determined in FixedUpdate itself, before the "internal physic update" of Unity.
  • Custom Good uses a simple self made interpolation, which lerps the position of the sprite from the previous rigidbody position to the last calculated rigidbody position. The last calculated rigidbody position is retrieved correctly after the "internal physic update" of Unity. The trick is to get the final rigidbody position in a Coroutine, which yields WaitForFixedUpdate().