Speed up the new OBJ exporter via bigger write buffer and parallelization.

This is a patch from Aras Pranckevicius, D13927. See that patch for full
details. On Windows, the many small fprintfs were taking up a large amount
of time and significant speedup comes from using snprintf into chained buffers,
and writing them all out later.
On both Windows and Linux, parallelizing the processing by Object can also lead
to a significant increase in speed.
The 3.0 splash screen scene exports 8 times faster than the current C++ exporter
on a Windows machine with 32 threads, and 5.8 times faster on a Linux machine
with 48 threads.

There is admittedly more memory usage for this, but it is still using 25 times
less memory than the old python exporter on the 3.0 splash screen scene, so
this seems an acceptable tradeoff. If use cases come up for exporting obj files
that exceed the memory size of users, a flag could be added to not parallelize
and write the buffers out every so often.

1 files changed, 6 insertions, 0 deletions

diff --git a/source/blender/io/wavefront_obj/CMakeLists.txt b/source/blender/io/wavefront_obj/CMakeLists.txt
index 296dd70b5a2..0b1be7946cf 100644
--- a/source/blender/io/wavefront_obj/CMakeLists.txt
+++ b/source/blender/io/wavefront_obj/CMakeLists.txt
@@ -56,6 +56,12 @@ set(LIB
   bf_blenkernel
 )
 
+if(WITH_TBB)
+  add_definitions(-DWITH_TBB)
+  list(APPEND INC_SYS ${TBB_INCLUDE_DIRS})
+  list(APPEND LIB ${TBB_LIBRARIES})
+endif()
+
 blender_add_lib(bf_wavefront_obj "${SRC}" "${INC}" "${INC_SYS}" "${LIB}")
 
 if(WITH_GTESTS)