OBB vs. OBB collision

/// <summary>
/// 4 body orientovaného obdélníku
/// - top-left, top-right, bottom-right, bottom-left !!! (clockwise order)
/// </summary>


/// <summary>
/// Test kolize - jestli dva orientované rectangles (ve světových souřadnicích) kolidují
/// </summary>
public static bool IsCollidingRectangles(Vector2[] a, Vector2[] b)
{
    if (!CollidesWith(a, b)) // Všechny 4 body b jsou za nějakou stranou a (tj. určitě není kolize)
        return false;
    if (!CollidesWith(b, a))
        return false;
    return true;
}

/// <summary>
/// Jestli koliduje a -> b (pak se testuje i obráceně...)
/// </summary>
public static bool CollidesWith(Vector2[] a, Vector2[] b)
{
    for (int i = 0; i < 4; i++)
    {
        int j = (i + 1) % 4;
        Vector2 vectorStart = a[j];
        Vector2 vectorDirection = a[i] - a[j];

        bool collisionFound = false;
        for (int y = 0; y < 4; y++)
            if (IsPointOnRightSide(vectorStart, vectorDirection, b[y]))
                collisionFound = true;

        if (!collisionFound)
            return false;
    }
    return true;
}

/// <summary>
/// Tests line (vector + point) vs. other point
/// - vectorDirection = LinePoint1 - VectorStart   (VectorStart = LinePoint2)
/// - returns true, if the point is on the right side of the line
/// </summary>
private static bool IsPointOnRightSide(Vector2 vectorStart, Vector2 vectorDirection, Vector2 point)
{
    Vector2 secondVector = point - vectorStart;
    float dotProduct = Vector2.Dot(vectorDirection, secondVector); // = skalární součin
    return dotProduct > 0f;
}