A long time ago in 2b4f223 I introduced a small logic change to the
handling of stacked entities. If two entities were standing on each
other the original code set the movement speed of the upper entity
to 0. It would be pushed or dragged by the lower entity. I changed
that in way that the upper entity got the same speed as the lower
entity. With that change it wasn't pushed or dragged but moving on
it's own. I hoped to fix some of the 'elevator hurts player or monster'
bugs.
That hope was wrong, at a later time we quirked all elevators that hurt
the player. Additionally the change lead to physics bugs if entities are
standing on high speed elevators (more than 200 units per seconds). So
revert it.
The actual fix was already committed as part of 69b6e5a. This is just a
little cleanup commit, mainly for documentation purposes.
This closes#320.
1) Do not increment the frame rate returned by SDL by 1. Incrementing
is unnessecary, more or less up to date versions on Nvidias, AMDs
and Intels GPU driver on relevant platform return an value that's
either correct or rounded up to next integer. And SDL itself also
rounds up to the next integer. At least in current versions. In fact,
incrementing the value by one is harmfull, it messes our internal
timing up and leads to subtile miss predictions. Working around that
in frame.c would add another bunch of fragile magic... So just do
it correctly. If someone still has broken GPU drivers or SDL versions
that are rounding down the could set vid_displayrefreshrate.
2) The calculation of the 5% security margin to pfps in frame.c was
wrong. It didn't take into account that rfps can be slightly wrong
in the first place, e.g. 60 on an 59.95hz display. Correct it by
comparing against rfps including the margin and not the plain value.
This bug was "fixed" by id with removing two lines in the ground entity
check. When cleaning up the game I added them back... I don't know if
it's really correct to just remove them, but let's try it. This fixes
issue #157.
