I've implemented an alternative method for detecting grid positions in an isometric Unity game without using a hitmap. Instead, I'm using a combination of mesh colliders and raycasting. Here's my implementation:

// ... other fields and methods ...

public bool IsOddRowAtPoint(Vector3 point)
{
    Ray ray = new Ray(point + Vector3.up * 10, Vector3.down);
    RaycastHit hit;
    if (meshCollider.Raycast(ray, out hit, 20f))
    {
        int triangleIndex = hit.triangleIndex * 3;
        int vertexIndex = triangles[triangleIndex];
        return isOddRow[vertexIndex];
    }
    return false; // Default value if no hit is detected
}

// ... method to create mesh and set up isOddRow list ...


// ... other fields and methods ...

void TouchCell(Vector3 position)
{
    position = transform.InverseTransformPoint(position);
    bool isOddRow = isoMesh.IsOddRowAtPoint(position);
    IsoCoordinates coordinates = IsoCoordinates.FromPosition(position, isOddRow);
    
    Debug.Log($"Touched at {coordinates.ToString()}, Is Odd Row: {isOddRow}");
}

public static IsoCoordinates FromPosition(Vector3 position, bool isOddRow)
{
    float x = position.x / IsoMetrics.cellWidth;
    float z = position.z / (IsoMetrics.cellHeight);
    int iZ = 0;
    if (isOddRow)
    {
        x -= 0.5f;
        z += 0.5f;
        iZ = Mathf.FloorToInt((z)) * 2 - 1;
    }
    else
    {
        iZ = Mathf.FloorToInt((z)) * 2;
    }
    int iX = Mathf.FloorToInt(x);
    return new IsoCoordinates(iX, iZ);
}

This approach uses a mesh collider and stores whether each triangle in the mesh belongs to an odd or even row. When detecting a grid position, it raycasts against the mesh and checks the isOddRow status of the hit triangle.

What I'm unsure of given my method

How does this method compare performance-wise to using a hitmap?

Are there any potential issues or edge cases I should be aware of?

Is there a more efficient way to store and retrieve the odd/even row information for each cell?

How well would this scale for larger grids?

My Grid Currently

Tags: [unity3d] [isometric] [grid] [game-development] [c#]