Tilemap basics in Unity - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Tilemap cell position code?

Consider this Unity C# code snippet that gets the cell position of a world point in a Tilemap:

Vector3 worldPos = new Vector3(2.5f, 3.7f, 0f);
Vector3Int cellPos = tilemap.WorldToCell(worldPos);
Debug.Log(cellPos);

What will be printed in the console?

Unity

Vector3 worldPos = new Vector3(2.5f, 3.7f, 0f);
Vector3Int cellPos = tilemap.WorldToCell(worldPos);
Debug.Log(cellPos);

A (2, 3, 0)

B (3, 4, 0)

C (2, 4, 0)

D (3, 3, 0)

💡 Hint

Remember that WorldToCell rounds down to the nearest cell coordinates.

The WorldToCell method converts a world position to the cell position by flooring the x and y values. So 2.5 becomes 2 and 3.7 becomes 3.

❓ Predict Output

intermediate

What does this code print when setting a tile?

Given a Tilemap and a TileBase tile, what will this code print?

Vector3Int pos = new Vector3Int(1, 1, 0);
tilemap.SetTile(pos, tile);
TileBase result = tilemap.GetTile(pos);
Debug.Log(result == tile);

Unity

Vector3Int pos = new Vector3Int(1, 1, 0);
tilemap.SetTile(pos, tile);
TileBase result = tilemap.GetTile(pos);
Debug.Log(result == tile);

A True

B False

C NullReferenceException

D Compilation error

💡 Hint

SetTile assigns the tile at the position, GetTile returns the tile at that position.

After setting the tile at position (1,1,0), GetTile returns the same tile object, so the comparison is true.

🔧 Debug

advanced

Why does this Tilemap code throw a NullReferenceException?

Look at this code snippet:

Tilemap tilemap;
void Start() {
    Vector3Int pos = new Vector3Int(0, 0, 0);
    TileBase tile = tilemap.GetTile(pos);
    Debug.Log(tile.name);
}

Why does this code throw a NullReferenceException?

Unity

Tilemap tilemap;
void Start() {
    Vector3Int pos = new Vector3Int(0, 0, 0);
    TileBase tile = tilemap.GetTile(pos);
    Debug.Log(tile.name);
}

A pos is invalid and causes GetTile to fail

B tilemap is not assigned and is null, so calling GetTile causes the exception

C tile is null because no tile exists at pos, so accessing tile.name causes the exception

D Debug.Log cannot print tile.name because TileBase has no name property

💡 Hint

Check if the tile exists at the position before accessing its properties.

If no tile exists at the given position, GetTile returns null. Accessing tile.name then causes a NullReferenceException.

🧠 Conceptual

advanced

How does the Tilemap's origin affect tile placement?

In Unity Tilemaps, what happens if you change the Tilemap's origin property?

A The origin changes the size of each tile in the Tilemap

B The origin determines the sorting order of tiles when rendered

C The origin sets the default tile used when no tile is placed

D The origin shifts the coordinate system, so tile positions are offset accordingly

💡 Hint

Think about how coordinates relate to tile positions.

The origin shifts the coordinate system of the Tilemap, so all tile positions are offset by the origin value.

❓ Predict Output

expert

What is the number of tiles after this code runs?

Consider this code that sets tiles in a Tilemap:

for (int x = 0; x < 3; x++) {
    for (int y = 0; y < 3; y++) {
        Vector3Int pos = new Vector3Int(x, y, 0);
        if ((x + y) % 2 == 0) {
            tilemap.SetTile(pos, tile);
        }
    }
}
int count = 0;
foreach (var pos in tilemap.cellBounds.allPositionsWithin) {
    if (tilemap.GetTile(pos) != null) count++;
}
Debug.Log(count);

What number will be printed?

Unity

for (int x = 0; x < 3; x++) {
    for (int y = 0; y < 3; y++) {
        Vector3Int pos = new Vector3Int(x, y, 0);
        if ((x + y) % 2 == 0) {
            tilemap.SetTile(pos, tile);
        }
    }
}
int count = 0;
foreach (var pos in tilemap.cellBounds.allPositionsWithin) {
    if (tilemap.GetTile(pos) != null) count++;
}
Debug.Log(count);

A 4

B 5

C 9

D 6

💡 Hint

Count how many positions satisfy (x + y) % 2 == 0 in a 3x3 grid.

Positions where (x + y) is even are (0,0), (0,2), (1,1), (2,0), (2,2) — total 5 tiles set.