User:Vasco.costa/GSoC15/logs

Community Bonding Period

I have made two patches for OpenCL (OCL) shot code. One patch refactors the existing sph (Sphere) shot code, and the another patch implements ehy (Elliptical Hyperboloid) shot code.

• https://sourceforge.net/p/brlcad/patches/341/
• https://sourceforge.net/p/brlcad/patches/346/

Background Research

• http://graphics.cs.kuleuven.be/publications/LD08CFRGRT/
• http://research.microsoft.com/en-us/um/people/cloop/garanzhaloop2010.pdf

Development Phase

Week 1 : 25-31 May

• Created some example .g files in mged for the primitives to be implemented this week. The Quick Reference Card proved to be quite useful.
• Do the matrix ops for ehy (Elliptical Hyperboloid) in the OpenCL side.
  • https://sourceforge.net/p/brlcad/patches/346/

• Made patch for ell (Generalized Ellipsoid) and arb8 (Arbitrary Polyhedron) OpenCL shots:
  • https://sourceforge.net/p/brlcad/patches/370/
• M1 complete: ellipsoid (ell), arb8 (arbitrary polyhedron) shot routines in OCL.

• Tried out a bunch of code browsing tools (cscope, LXR, doxygen, etc). The NetBeans IDE seems the most promising.

Week 2 : 1-7 Jun

• Read code to better understand the main rendering loop. It seems to be something like this:

do_frame() → do_run() → worker()* → do_pixel()* → rt_shootray()* → rt_*_shot()

The code is recursive (which is problematic for OpenCL). I'll work on a simplified version of the rendering loop which only does the primary rays in C as a first approach. After I get the non-recursive parallel friendly C code I'll work on the OpenCL port.

• Updated project proposal on Google Melange.

• SVN r65153 fails to compile with a bogus error of an unused variable that's actually being used its just that GCC 4.9.1 is too dumb to figure that out.
  • https://sourceforge.net/p/brlcad/bugs/365/

• Upgraded Ubuntu and GCC.

• Made simple ray generation code in C.
• Made simple frame buffer write code in C.
• Made simple diffuse shading code in C.

Week 3 : 8-14 Jun

• Added the main boolean weaving code to our minimal renderer.
• Eliminated some gotos and made the code more thread safe.
• The simple renderer patches are in the mailing-list.

Week 4 : 15-21 Jun

• Added OpenMP compile support. Use OpenMP constructs to launch the rendering threads. This work still has some bugs in it.
• Alpha M2 patch. in mailing-list.

• Read code to better understand the main spatial partition construction routines. They seem to be something like this:

rt_prep_parallel() → rt_cut_it() → rt_nugrid_cut()

We need something less complex that is more amenable to porting to OpenCL. So I will be implementing the Lagae & Dutré compact grid construction algorithm published at EGSR. First I will program in ANSI C then I will port the code to OpenCL.

• Started work on M3: grid spatial partitioning in OCL.
  • https://sourceforge.net/p/brlcad/patches/379/
• ANSI C Lagae & Dutré grid construction code.

Week 5 : 22-28 Jun

• Took time off from the project to go to the CGI'15 conference.

Week 6 : 29 Jun-5 Jul

• GSoC Midterm Evaluations.

Week 7 : 6 Jul-12 Jul

• Evaluating algorithms for grid construction.
• Selecting OpenCL kernels we can use to support grid construction. It seems PyOpenCL has some kernels we could use. Now the question is how to extricate the OpenCL/C from the Python...

Week 8 : 13 Jul-19 Jul

• ANSI C grid traversal code.
• OpenCL grid construction on the GPU.
• M3 complete: grid spatial partitioning in OCL.