3d格斗游戏的碰撞检测

sea_bug

作者：xtxy的专栏

在网上搜索了一些资料，最后采用了obb的碰撞检测，方法如下：

1 在3ds max中，将biped骨骼的大小设置恰当，在使用方框显示骨骼的时候能比较准确的包围住角色，如下图:



然后选中所有的骨骼，使用maxscript脚本导出来。脚本其实比较简单，代码如下：

---------------------------------------------------------------------------------

-- file function
fn existFile fname = (getfiles fname).count != 0

-- main
fileName = "F://Work//MyProjects//3DGame//3dsmax_data//fight_action_data.txt"
if existFile fileName then deleteFile fileName
createFile fileName
fp = openFile fileName mode:"at"

for sel in selection do
(
    -- get bounding box
    bb = nodeLocalBoundingBox sel
    -- print bb
    -- print sel.transform
    -- print "-------------"
    position = (bb[2] + bb[1]) / 2
    size = bb[2] - bb[1]
   
    len = sel.transform[1].x ^ 2 + sel.transform[1].y ^ 2 + sel.transform[1].z ^ 2
    len = len ^ 0.5
    x1 = sel.transform[1].x / len
    y1 = sel.transform[1].y / len
    z1 = sel.transform[1].z / len
   
    extent1 = (size.x * x1 + size.y * y1 + size.z * z1) / 2
   
   
    len = sel.transform[2].x ^ 2 + sel.transform[2].y ^ 2 + sel.transform[2].z ^ 2
    len = len ^ 0.5
    x2 = sel.transform[2].x / len
    y2 = sel.transform[2].y / len
    z2 = sel.transform[2].z / len
   
    extent2 = (size.x * x2 + size.y * y2 + size.z * z2) / 2
   
    len = sel.transform[3].x ^ 2 + sel.transform[3].y ^ 2 + sel.transform[3].z ^ 2
    len = len ^ 0.5
    x3 = sel.transform[3].x / len
    y3 = sel.transform[3].y / len
    z3 = sel.transform[3].z / len
   
    extent3 = (size.x * x3 + size.y * y3 + size.z * z3) / 2
   
    print sel.name to:fp
   
    print((extent1 as string) + "," + (extent2 as string) + "," + (extent3 as string)) to:fp
    print((position.x as string) + "," + (position.z as string) + "," + ((-position.y) as string)) to:fp
    print((x1 as string) + "," + (z1 as string) + "," + ((-y1) as string)) to:fp
    print((x2 as string) + "," + (z2 as string) + "," + ((-y2) as string)) to:fp
    print((x3 as string) + "," + (z3 as string) + "," + ((-y3) as string)) to:fp
)

close fp

---------------------------------------------------------------------------------

生成的文件格式如下：

---------------------------------------------------------------------------------
"Bip01"
"2.18656,2.18656,2.18656"
"0.583941,40.3044,-1.10637"
"0.555635,0.0,0.831426"
"0.831426,0.0,-0.555635"
"0.0,1.0,0.0"
"Bip01 Pelvis"
"6.1669,5.71345,5.46639"
"0.583941,40.3044,-1.10637"
"-1.21579e-006,1.0,6.67132e-007"
"0.481059,0.0,0.876688"
"0.876688,1.3868e-006,-0.481059"
…………
…………
---------------------------------------------------------------------------------

其中每个盒子的第二行数据就是盒子的半个长度，宽度和高度，和第四行至第六行的变换矩阵是一一对应的
第三行就是盒子的中心点位置，是全局坐标
第四行至第六行就是盒子在三个面方向上的标准变换矩阵了。

数据有了之后，就可以用obb碰撞算法进行碰撞检测了。
obb算法可以参考：
http://hi.baidu.com/jorbin/blog/item/2e7c2df5c146f423bd310977.html
或者他引用的一个国外的网址：
http://www.gamasutra.com/view/feature/3383/simple_intersection_tests_for_games.php?page=5

最后贴一个我在ogre里面根据obb数据画出来的碰撞盒子的图片，主要作用是调试碰撞检测是否正确：

ashuralyk

嗯，基本原理就是这样。

yuxj

好贴，感谢分享