changing intersection region color of transparent object on raphaeljs svg?

im working on a web app. project and i need to change intersection region color for transparent objects. to set it darker i mean the intersection region color开发者_StackOverflow only the intersection region not the whole object.

intersection will not always be rectangular. there will also be intersection with the image based svg objects. so... creating an overlay object by calculating intersection region is quite impossible.

the only solution left is to interfere with render process of svg. is there possible way to do this?? :/

and please tell me if this is not possible.

If you use MVVM, you could let your viewmodel handle the intersections. Say you have two layers in your presentation. One layer has the original shapes, the other layer has the intersections. The intersections could be bound to an Intersections property in your viewmodel. That Intersections property could be a collection of shape data(point arrays, or whatever).