Input axis for smooth movement in Unity - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Unity C# code for horizontal input?

Consider the following Unity C# script snippet inside Update(). What will be the value of moveHorizontal if the player presses the right arrow key for a short moment?

Unity

float moveHorizontal = Input.GetAxis("Horizontal");
Debug.Log(moveHorizontal);

A Always 1 immediately when the key is pressed

B A value smoothly increasing from 0 to 1 over a short time

C Always 0 regardless of input

D A value instantly jumping between -1 and 1 with no smoothing

💡 Hint

Think about how Input.GetAxis works compared to Input.GetAxisRaw.

Input.GetAxis returns a value that changes smoothly from 0 to 1 when pressing a key, allowing smooth movement. It does not jump immediately to 1.

❓ Predict Output

intermediate

What does this code print when pressing left arrow key?

Given this code snippet inside Update(), what will be printed when the player presses the left arrow key?

Unity

float moveHorizontal = Input.GetAxisRaw("Horizontal");
Debug.Log(moveHorizontal);

A Always 0 regardless of input

B A value smoothly changing from 0 to -1

C A value of -1 immediately when the key is pressed

D A value of 1 immediately when the key is pressed

💡 Hint

Input.GetAxisRaw returns raw input without smoothing.

Input.GetAxisRaw returns -1 immediately when pressing left arrow, no smoothing.

🔧 Debug

advanced

Why does this movement feel jerky?

This Unity C# code moves a player horizontally using Input.GetAxisRaw. Why might the movement feel jerky?

Unity

float move = Input.GetAxisRaw("Horizontal");
transform.Translate(move * speed * Time.deltaTime, 0, 0);

A Because Input.GetAxisRaw returns values instantly without smoothing, causing sudden jumps

B Because Time.deltaTime is not used, causing inconsistent movement

C Because transform.Translate is called outside Update, causing lag

D Because speed is multiplied twice, causing too fast movement

💡 Hint

Think about how input smoothing affects movement feel.

Using Input.GetAxisRaw causes instant input changes, which can make movement feel jerky compared to smooth input.

🧠 Conceptual

advanced

How to achieve smooth acceleration using input axis?

Which approach best achieves smooth acceleration and deceleration for player movement in Unity?

A Use Input.GetAxisRaw and add a fixed value to position each frame

B Use Input.GetAxisRaw and multiply by speed without Time.deltaTime

C Use Input.GetAxis and set position directly without Time.deltaTime

D Use Input.GetAxis and multiply by speed and Time.deltaTime in Update

💡 Hint

Smooth input and frame-rate independent movement are key.

Using Input.GetAxis provides smooth input values, and multiplying by Time.deltaTime ensures smooth movement regardless of frame rate.

❓ Predict Output

expert

What is the value of 'velocity' after this code runs?

Given this Unity C# code snippet inside Update(), what is the value of velocity after pressing right arrow key for 1 second continuously? Assume speed = 5f and frame rate is 60 FPS.

Unity

float moveInput = Input.GetAxis("Horizontal");
float velocity = 0f;
velocity += moveInput * speed * Time.deltaTime;

A Always 0 because velocity is reset each frame

B Exactly 5 immediately after pressing the key

C Approximately 0.0833 (5 * 1/60) after one frame, accumulating over frames

D Approximately 1 after one second

💡 Hint

Consider variable scope and how 'velocity' is updated each frame.

The variable velocity is reset to 0 every frame because it is declared inside Update(). So it never accumulates.

Practice

1. What does the Unity Input.GetAxis function return when used for movement?

easy

A. A string describing the input device

B. An integer value of either 0 or 1 indicating button press

C. A boolean value true if any key is pressed

D. A smooth float value between -1 and 1 representing input strength

Solution

1. Step 1: Understand Input.GetAxis behavior

   Input.GetAxis returns a float value that smoothly changes between -1 and 1 based on input device movement, like joystick or keyboard keys.

2. Step 2: Compare with other input types

   Unlike Input.GetButton or Input.GetKey, it does not return boolean or integer but a float for smooth control.

3. Final Answer:

   A smooth float value between -1 and 1 representing input strength -> Option D

4. Quick Check:

   Input.GetAxis returns float between -1 and 1 [OK]

Hint: Remember: GetAxis gives smooth float, not just on/off [OK]

Common Mistakes:

• Thinking it returns only 0 or 1
• Confusing with boolean input methods
• Expecting integer values instead of float

2. Which of the following is the correct syntax to read horizontal input axis in Unity?

easy

A. float move = Input.GetAxis.Horizontal();

B. float move = Input.GetAxis(Horizontal);

C. float move = Input.GetAxis("Horizontal");

D. float move = Input.GetAxis['Horizontal'];

Solution

1. Step 1: Check method usage

   Input.GetAxis requires a string parameter with axis name in quotes, e.g., "Horizontal".

2. Step 2: Validate syntax correctness

   float move = Input.GetAxis("Horizontal"); uses correct method call with parentheses and string argument. Other options misuse syntax with missing quotes, wrong brackets, or dot notation.

3. Final Answer:

   float move = Input.GetAxis("Horizontal"); -> Option C

4. Quick Check:

   Use parentheses and quotes for axis name [OK]

Hint: Always put axis name in quotes inside GetAxis() [OK]

Common Mistakes:

• Omitting quotes around axis name
• Using square brackets instead of parentheses
• Calling GetAxis as a property instead of method

3. What will be the output of the following Unity C# code snippet if the player presses the right arrow key for horizontal input?

float horizontal = Input.GetAxis("Horizontal");
float speed = 5f;
float movement = horizontal * speed * Time.deltaTime;
Debug.Log(Math.Round(movement, 2));

medium

A. A positive float value close to 0.08 (assuming 60 FPS)

B. Zero, because Input.GetAxis returns only integers

C. A negative float value

D. An error because Time.deltaTime is not used correctly

Solution

1. Step 1: Understand Input.GetAxis with right arrow

   Pressing right arrow sets horizontal axis near +1 smoothly.

2. Step 2: Calculate movement value

   Movement = 1 * 5 * (1/60) ≈ 0.0833, rounded to 0.08.

3. Final Answer:

   A positive float value close to 0.08 (assuming 60 FPS) -> Option A

4. Quick Check:

   Right arrow -> horizontal ~1 -> movement ~0.08 [OK]

Hint: Multiply axis by speed and deltaTime for smooth movement [OK]

Common Mistakes:

• Assuming Input.GetAxis returns only 0 or 1
• Ignoring Time.deltaTime in movement calculation
• Confusing positive and negative axis values

4. Identify the error in this Unity C# code for smooth horizontal movement:

float move = Input.GetAxis(Horizontal);
transform.Translate(move * speed * Time.deltaTime, 0, 0);

medium

A. Missing quotes around "Horizontal" in GetAxis

B. Using Translate instead of MovePosition

C. Multiplying by Time.deltaTime is incorrect

D. Variable 'speed' is not declared

Solution

1. Step 1: Check GetAxis parameter syntax

   The axis name must be a string in quotes. Here, Horizontal is used without quotes causing a compile error.

2. Step 2: Verify other code parts

   Using Translate with speed and Time.deltaTime is correct. Variable 'speed' is assumed declared elsewhere.

3. Final Answer:

   Missing quotes around "Horizontal" in GetAxis -> Option A

4. Quick Check:

   Axis names need quotes in GetAxis() [OK]

Hint: Always put axis names in quotes to avoid errors [OK]

Common Mistakes:

• Forgetting quotes around axis name
• Confusing Translate with other movement methods
• Assuming Time.deltaTime is optional

5. You want to move a character smoothly left and right using the horizontal axis, but only when the input magnitude is greater than 0.1 to avoid tiny unwanted movements. Which code snippet correctly implements this in Unity C#? A)

float h = Input.GetAxis("Horizontal");
if (h > 0.1f) {
    transform.Translate(h * speed * Time.deltaTime, 0, 0);
}

B)

float h = Input.GetAxis("Horizontal");
if (Mathf.Abs(h) > 0.1f) {
    transform.Translate(h * speed * Time.deltaTime, 0, 0);
}

C)

float h = Input.GetAxis("Horizontal");
if (h > 0.1f && h < -0.1f) {
    transform.Translate(h * speed * Time.deltaTime, 0, 0);
}

D)

float h = Input.GetAxis("Horizontal");
if (h != 0) {
    transform.Translate(h * speed * Time.deltaTime, 0, 0);
}

hard

A. Checks if h > 0.1f only (ignores negative direction)

B. Uses Mathf.Abs to check if absolute value of h is greater than 0.1

C. Checks if h is both greater than 0.1 and less than -0.1 (impossible)

D. Checks if h is not zero, allowing very small movements

Solution

1. Step 1: Understand input magnitude filtering

   We want to ignore small inputs less than 0.1 in magnitude, so absolute value check is needed.

2. Step 2: Analyze each condition

   Checks if h > 0.1f only (ignores negative direction) fails to move left since negative h won't exceed 0.1f. Uses Mathf.Abs to check if absolute value of h is greater than 0.1 uses Mathf.Abs(h) > 0.1f, which is concise and correct. Checks if h is both greater than 0.1 and less than -0.1 (impossible)'s AND condition is impossible. Checks if h is not zero, allowing very small movements allows any non-zero input, including tiny values.

3. Final Answer:

   Uses Mathf.Abs to check if absolute value of h is greater than 0.1 -> Option B

4. Quick Check:

   Use Mathf.Abs(h) > threshold for magnitude check [OK]

Hint: Use Mathf.Abs to check input magnitude for smooth control [OK]

Common Mistakes:

• Checking only positive direction (h > 0.1f), ignoring negatives
• Not using absolute value to check magnitude
• Allowing tiny inputs by only checking h != 0