[Soc-2012-dev] GSoC BGE Fixup Status Report Week 12

[Mitchell Stokes]

Here is my report for week 12:
http://mogurijin.wordpress.com/2012/08/10/gsoc-bge-fixup-status-report-week-12/

Task List:
http://wiki.blender.org/index.php/User:Moguri/GSoC_2012_BGE_Fixup_Docs

Mentor: Dalai

Contents of report:
What did you do this week?
While I fixed a couple of bugs, I spent way more time on optimizing
this week. I spent some time with AMD’s GPU PerfStudio 2 on an AMD
card. After a lot of profiling and toying around, I found that
fragment shaders were really slowing down the Necrosys map. I did some
research and decided to try implementing a depth pre-pass/Pre-Z pass
to reduce overdraw and the amount of time needed to process fragments
by culling them with a depth test. For more information on early depth
testing, there is this article from AMD[0], which I found very
helpful. This yielded a 60% increase in the fps of the Necrosys map
(going from about 63fps to about 104fps) on my system. I started a
thread on Blender Artists[1] to try and collect more data on how this
optimization affects other scenes.

I also implemented display lists for shadows, but this gave no
noticeable performance difference since the bottleneck was not in
transferring vertices.

Tracker stats:
New: 4
Closed: 2 (2 by me)
Net Change: +2
Current: 154

What do you plan to do next week?
Next Monday is the “suggested ‘pencils down’ date,” but I don’t think
it affects my project a whole lot this year since most of what I’m
doing is cleaning and scrubbing. I have some more test files that I
will take a look at for optimization. Maybe I can also look into
closing enough reports to get back down to three pages in the tracker.

Are there any problems that will require extra attention and what
impact will they have on your proposed schedule?
Nope, things are going smoothly.

Are there any builds available?
There are some on GraphicAll.

Cheers,
Moguri

[0] http://developer.amd.com/media/gpu_assets/depth_in-depth.pdf
[1] http://blenderartists.org/forum/showthread.php?263184-Dev-Pre-Z-Optimization-in-the-BGE-(testers-needed!)