Slope fixes
This branch fixes the following slope-related physics and rendering bugs:
* Rings in multiplayer stages respawning inside slopes (even despite being able to spawn ABOVE them on map load)
* Player starts spawning players inside slopes
* Elemental flame trails not appearing if a player spindashes UP a slope; see issue #21
* Dying players "jumping" off slopes to the side if they were previously standing on one
* Some issues with FOF slope rendering
* Various issues with sprites displaying through walls adjacent to slopes
Other features added:
* Objectplace now supports slopes (this is Inuyasha's doing)
* Automap in DEVMODE now supports slopes (my doing)
Just making this merge request now rather than later, ~~in case I decide not to make any more fixes for the time being~~ (this branch doesn't seem to want to die lol), and so we can get these merged in as soon as the code's all been checked over.
See merge request !50
xorshift* PRNG
This needs testing to ensure I didn't mess anything up switching function names around.
Our PRNG sucks. This is probably obvious. I wish I had known better at the time I implemented it, but oh well.
The replacement is an xorshift* PRNG variant with period 2^32 - 1 (meaning that the PRNG state will loop after four billion calls ... that's not likely to happen), versus the old PRNG's period of about 2^22 (?). The output is also much more random and less predictable; the old PRNG would fall into a predictable loop of output after about 4000 numbers were generated, which isn't much.
The PRNG here also outputs numbers as fixed point from [0,1) (that's 0 to FRACUNIT-1, in other words) instead of single bytes at a time. This makes it much easier to calculate things for, say, P_RandomRange and P_RandomKey. A new macro, P_RandomChance(p), is now in use that returns true _p_ percent of the time, where _p_ is a fixed_t probability from 0 (0%) to FRACUNIT (100%).
This doesn't affect netgames at all; the code for seed saving and restoring is identical (aside from a check to prevent seed being set to 0, which breaks xorshift PRNGs). Demos break, but A: _duh_ and B: they're already broken by all the changes to physics to accommodate slopes.
P_Random is deprecated in Lua, as the function was renamed to P_RandomByte. Aside from that, nothing special.
See merge request !64
Skybox hotfix
This branch fixes how, for a skybox with both a centerpoint and viewpoint, the first person view code did not take the centerpoint's angle into account. So when the centerpoint's angle is NOT 0 (or a multiple of 360), this results in the skybox "moving the wrong way" when you're viewing the skybox this way and moving about.
...yeah sorry guys, I commited to a copy of next again, whoops. Cherry-pick the relevant commit into master if this works out fine - after all, this shouldn't affect netgames I think (it's purely about rendering after all)
See merge request !56
* add skidtime, which we forgot before 2.1 release apparently
* change tics from INT16 to INT32
* change eflags from UINT8 to UINT16
* change actionspd/mindash/maxdash from INT32 to fixed_t
Until we use something besides Native MIDI to play
back MIDI music, MIDI volume changing is disabled
since it causes way too much of a damn headache.
(It's not even our fault, it's fucking MS.)
Fix for teetering on PolyObjects
So... somebody goofed and didn't realise PolyObject sectors could be added to the sector node list for each object (which is referenced by mobj->touching_sectorlist), via their linedefs if they are nearby the player (yes, PolyObject linedefs are special and get to move about the level). As it turns out, this allows even INTANGIBLE PolyObjects to make you teeter in a seemingly inexplicable way.
What is happening is that PolyObject sectors, when they are added to the mentioned lists, are then checked under normal sector teetering conditions - if the player is above the floorheight by 24 FUs, you're officially teetering unless stated otherwise. The actual PolyObject teetering code can't help you here if the conditions are right, especially if they're taller than 24 FU in height.
There are a number of things wrong with the teetering code in general that I'd like to sort eventually, but at least now teetering on PolyObjects is fixed at last ...right? Please check the branch out if you can to check this, obviously.
See merge request !54
Fixes for patch scaling and V_FLIP usage
The following issues are fixed by this branch:
* a patch using both scaling and V_FLIP does not appear in the "correct" place on the screen. Thanks to LJSonic for pointing this out to me on 'fun
* Scaled and/or V_FLIPed patches wrap at the left/right screen edges even though they're not supposed to. V_FLIP patches at these edges may also crop the wrong side of the patch if they're at the right edge.
See merge request !60
Some fixes for portals
Specifically the following things are fixed in this branch:
* a memory leak resulting from not clearing away clipping-related arrays each tic you view a portal
* a very specific crash to do with portals sometimes (unintentionally) using a hack on drawsegs that don't actually belong to them ...which results in a crash if the drawsegs in question have midtextures. I reported it on the MB a year ago, with a test map included there: https://mb.srb2.org/showthread.php?t=38199&page=4#79
* another specific crash to do with mirrored (horizontally flipped) sprites that are scaled, particularly when you cover up the left edge of them via portals at the least. Needs more testing to be absolutely sure this is fixed, and is also reproducable in the test map linked in the post above
May be fine to merge changes into master too, I don't really know exactly
See merge request !42
Camera fix
This fixes the third person camera being silly around intangible PolyObjects, particularly the fact they can affect the camera's floorz and ceilingz even though I see no reason why they should do so.
Also a good reminder that POF_SOLID is the same as POF_CLIPLINES and POF_CLIPPLANES combined, which is probably how this issue came about to begin with. Can't say that with certainty of course.
See merge request !57
P_ClosestPointOnLine changes
P_ClosestPointOnLine can now (optionally) take custom coordinates for two points that you want to make up a "line", instead of just actual linedefs.
Complete syntax for P_ClosestPointOnLine as of this branch:
```lua
-- syntax for a real linedef (which is already in 2.1.14):
P_ClosestPointOnLine(x, y, line)
-- syntax for a fake line with vertexes (x1,y1) and (x2,y2):
P_ClosestPointOnLine(x, y, x1, y1, x2, y2)
```
See merge request !61
