像素级碰撞检测对小物体失败。（Java）

Question

对于一个项目，我们得到了一个游戏引擎，用来创建一个游戏。作为其中的一部分，我们必须在通过边界盒检测方法发现可能的冲突后实现像素级的冲突检测。我已经实现了这两个，但是我的像素级测试对于小对象（在本例中是项目符号）失败了。我已经检查过它是否适用于慢速子弹，但它也失败了。

对于我的像素级实现，我使用可用的IntBuffer为每个纹理创建位掩码（ByteBuffer也可用？）。IntBuffer是RGBA格式的，它的大小是width*height。我将它放在一个2D数组中，并用1替换所有的非零数字来创建掩码。在边界框的冲突之后，我找到重叠表示的矩形（使用.createintersection），然后使用bitwise和检查该交集内的两个sprite的映射，以获得非零像素。

下面是我的像素级测试代码：

/**
 * Pixel level test
 *
 * @param rect the rectangle representing the intersection of the bounding
 * boxes
 * @param index1 the index at which the first objects texture is stored
 * @param index the index at which the second objects texture is stored
 */
public static boolean isBitCollision(Rectangle2D rect, int index1, int index2)
{
    int height = (int) rect.getHeight();
    int width = (int) rect.getWidth();

    long mask1 = 0;
    long mask2 = 0;

    for (int i = 0; i < width; i++)
    {
        for (int j = 0; j < height; j++)
        {
            mask1 = mask1 + bitmaskArr[index1].bitmask[i][j];//add up the current column of "pixels"
            mask2 = mask2 + bitmaskArr[index2].bitmask[i][j];

            if (((mask1) & (mask2)) != 0)//bitwise and, if both are nonzero there is a collsion
            {
                return true;
            }
            mask1 = 0;
            mask2 = 0;
        }

    }


    return false;
}

这几天来我一直在为这件事苦苦挣扎，任何帮助都将不胜感激。

Answer 1

我设法解决了我自己的问题，现在它正常运作。对于任何感兴趣的人，我所做的是找到由两个sprite的两个边界框的重叠创建的矩形。然后我把每一个物体连同它一起落到原点，相对来说，相交的矩形。需要注意的是，我将每个对象放置到一个“单独”的原点--即我实际上有两个相交的矩形--每个相交一个。每个相交矩形的坐标，现在在两个对象的位掩码2D数组的边界中，用来检查两个对象重叠的正确区域：

我通过位掩码从下到上，从左到右循环，作为上侧提供的图像数据--显然这是图像数据的标准。

 /**
 * My Pixel level test - 2D
 *
 * @param rect the rectangle representing the intersection of the bounding
 * boxes
 * @param index1 the index at which the first objects texture is stored
 * @param index2 the index at which the second objects texture is stored
 * @param p1 the position of object 1
 * @param p2 the position of object 2
 * @return true if there is a collision at a pixel level false if not
 */
//public static boolean isPixelCollision(Rectangle2D rect, Point2D.Float p1, Bitmask bm1, Point2D.Float p2, Bitmask bm2)
public static boolean isPixelCollision(Rectangle2D rect, Point2D.Float p1, int index1, Point2D.Float p2, int index2)
{
    int height = (int) rect.getHeight();
    int width = (int) rect.getWidth();

    byte mask1 = 0;
    byte mask2 = 0;

    //drop both objects to the origin and drop a rectangle of intersection for each along with them
    //this allows for us to have the co-ords of the rect on intersection within them at number that are inbounds.
    Point2D.Float origP1 = new Point2D.Float((float) Math.abs(rect.getX() - p1.x), (float) Math.abs(rect.getY() - p1.y));//rect for object one
    Point2D.Float origP2 = new Point2D.Float((float) Math.abs(rect.getX() - p2.x), (float) Math.abs(rect.getY() - p2.y));//rect for object two

    //to avoid casting with every iteration
    int start1y = (int) origP1.y;
    int start1x = (int) origP1.x;
    int start2y = (int) origP2.y;
    int start2x = (int) origP2.x;

    //we need to loop within the rect of intersection
    //goind bottom up and left to right
    for (int i = height - 1; i > 0; i--)
    {
        for (int j = 0; j < width; j++)
        {
            mask1 = bitmaskArr[index1].bitmask[start1y + i][start1x + j];
            mask2 = bitmaskArr[index2].bitmask[start2y + i][start2x + j];
            if ((mask1 & mask2) > 0)
            {
                return true;
            }
        }

    }
    //no collsion was found
    return false;
}