On Friday, 15 November 2013 at 14:01:36 UTC, Chris Cain wrote:
On Friday, 15 November 2013 at 13:32:38 UTC, Mikko Ronkainen
wrote:
Ok, thanks! That linked list cache thrashing was just the
thing I knew that I don't know :)
Let's say I just use dynamic array and grow it when adding new
particles to the system, and when particles die, just set
their dead flag on. This means that, when adding a new
particle, I need to scan the array first for possible dead
particles that can be reused. Is there some trick that could
be used here to reduce excessive searching/iteration?
Instead of having a "dead flag", you could swap (
http://dlang.org/phobos/std_algorithm.html#swap ) the dying
particle with the last particle in the list and then decrement
the list's length.
This swapping might even speed up the normal particle processing,
because with a mix of dead and alive particles the flag checking
could confuse the branch predictor.
http://stackoverflow.com/questions/11227809/why-is-processing-a-sorted-array-faster-than-an-unsorted-array
Ultimately, if flag or swap is faster must be measured. Profiling
and bencharking are your friends, if you want to optimize your
particle system. For a start use an array and either method.
