Ratio of AABB box, OBB box, and ball

 

 

1) AABB enclosure: The AABB enclosure is an enclosure that is aligned with the coordinate axis. It is simple and compact. (especially for thin and long objects placed in the diagonal corner, AABB is used, will leave a very large corner gap, resulting in a large number of not required box intersection test ). After an object is rotated, the AABB must be rotated and updated in the same way. After the object is deformed, the corresponding surrounding box of the deformed basic geometric elements must be calculated again; then, the AABB of the parent node can be merged from bottom to top from the AABB of the child node, and the nested box tree is updated.

 

 

 

2) OBB surround box: the OBB collision check box method is better in tightness, which can greatly reduce the number of surrounding boxes for the crash and intersection test. Therefore, the overall performance is better than that of AABB and the surround ball, in addition, the real-time performance is high. After an object is rotated, you only need to perform the same rotation on OBB. Therefore, for collision detection between rigid bodies, OBB is a good choice. So far, there is no effective method to better solve the problem of updating the OBB tree after object deformation, and the price for calculating the OBB of each node is too high. Therefore, OBB is not applicable to complex environments including software objects.

Extended exam:

Http://hi.baidu.com/jorbin/blog/item/2e7c2df5c146f423bd310977.html/cmtid/c13785356aaa081f90ef39bf

Http://www.cnblogs.com/gamesoul/archive/2007/05/29/764523.html

 

 

 

3) Ball surround: the ball surround collision detection method is to use a sphere to enclose the entire body, whether it is a ry or an intersection test is very easy; but its tightness is too poor. In addition to the distribution of the three axes in a geometric body that is more uniform than that of the primary axis, the difference will leave a large gap. It takes a lot of preprocessing time to construct a good hierarchical structure to approach the object. After the object is deformed, the ball tree must be computed again. Therefore, it is a type of box that uses less than the limit. When an object is rotated, the ball does not need to be updated. This is an excellent feature of the ball. When a geometric object is rotated frequently, maybe it is better to use the ball to enclose it.

 

 

Bian Meiling, Ren Jianping. Research on the Technology of cylinder collision detection. Development of mechanical management. 2008