unity3d - 找一个区域有空位的函数，没找到怎么报错？

Question

下面的函数 FindEmptySpace() 在一个区域中找到一个随机的空白空间。它通过在区域内随机选择坐标，检查那里是否已经存在任何东西，然后循环这个过程，直到它成功找到一个没有任何东西的位置，然后返回它来做到这一点。

效果很好，但我刚刚意识到，如果没有可用空间，这可能会陷入永无止境的循环。但是函数如何知道何时没有可用的空白空间并返回错误？

static function FindEmptySpace ()
{
    var sphereRadius = 2.0;
    while ( true )
    {
        var spawnPos = RandomPoint();   // Get random position within level bounds

        if ( !Physics.CheckSphere( spawnPos, sphereRadius ) )   // Check if area is empty
        break;  
    }
    return spawnPos;    // Return empty location
}

Answer 1

我按照任南的建议改写了，现在循环到边界的边缘，如果再次到达起点，什么都没找到，返回null。

未经测试，但我认为这是一个很好的解决方案。

static function CheckForEmptySpace ()
{
    var bounds = GameController.levelAttributes.bounds;
    var sphereRadius = 2.0;
    var startingPos = Vector3( Random.Range(bounds.xMin, bounds.xMax), 0, Random.Range(bounds.yMin, bounds.yMax) );
    // Loop, until empty adjacent space is found
    var spawnPos = startingPos; 
    while ( true )
    {
        if ( !Physics.CheckSphere( spawnPos, sphereRadius ) )   // Check if area is empty
            return spawnPos;    // Return location
        else
        {
            // Not empty, so gradually move position down. If we hit the boundary edge, move and start again from the opposite edge.
            var shiftAmount = 2;
            spawnPos.z -= shiftAmount;
            if ( spawnPos.z < bounds.yMin )
            {
                spawnPos.z = bounds.yMax;
                spawnPos.x += shiftAmount;
                if ( spawnPos.x > bounds.xMax )
                    spawnPos.x = bounds.xMin;
            }
            // If we reach back to a close radius of the starting point, then we didn't find any empty spots
            var proximity = (spawnPos - startingPos).sqrMagnitude;
            var range = shiftAmount-0.1;    // Slight 0.1 buffer so it ignores our initial proximity to the start point
            if ( proximity < range*range )  // Square the range
            {
                Debug.Log( "An empty location could not be found" );
                return null;
            }
        }
    }
}