Computer Science Canada

sorting attributes of an object
Author:  shaon [ Fri Apr 11, 2008 8:34 pm ]
Post subject:  sorting attributes of an object
When working in 3D, objects in the far back are drawn first with the closest object to camera being the last object to be drawn. I stored the center coordinate of any object in space as it's attribute (ie. self.position = [x,y,z]). I then made an enviroment class that stores(in a list) and transforms this point based on user control. The problem that I havent figured out how to overcome is how to efficiently sort all the objects in 3D space that are held in a list, so that the object with the highest "z" point is first on the list and lowest "z" point object is last on the list.

I guess my question is, how do I sort objects in a list based on one of their attributes? I tried to make a modified merge sort, but sorting 1000 integers sucks up 16-17 ms and I can only afford 40 ms total for my game (25 fps).

In fact is there a better way to draw objects in a 3D plane correctly rather than sorting? I feel sorting takes too much processing time.....
Author:  rdrake [ Fri Apr 11, 2008 9:39 pm ]
Post subject:  Re: sorting attributes of an object
You can and it's fairly easy. Read this.

In particular, pay attention to this snippet:
Python:
>>> a = [Spam(1, 4), Spam(9, 3), Spam(4, 6)]
>>> a.sort(key=lambda obj:obj.eggs())
>>> for spam in a:
>>>   print spam.eggs(), str(spam)
3 12
4 5
6 10
You can also write a key function to use instead of using a lambda and assign it to key, it's your call. Obviously obj is your object and eggs is a function of some sort.
Author:  shaon [ Fri Apr 11, 2008 10:24 pm ]
Post subject:  Re: sorting attributes of an object
thx, I tried to search for the sort techniques in the manual and I couldn't find anything. Thank you oh so very much!!!! One step closer to a full-fledged 3D world....

:


You can syndicate this boards posts using the file backend.php or view the topic map using sitemap.php.

Terms of Use | Privacy Policy