*The No Physics flag now works (Red, you might want to doublecheck this to see whether I haven't missed any eosteric stuff out). Going downhill is a little bumpy, and I'm not sure whether that's good or not. Someone help me out here?
*The SRB2CB typeshims are now behind #ifdef ESLOPE_TYPESHIM instead of #if 1 for easier disabling.
*Slopes' downhill thrusts are now scaled with regards to object gravity. This is actually untested in gravities other than normal and reverse normal but it's one line which can be easily reverted in that circumstance. I also checked with MI to make sure this is how it's calculated elsewhere, so fingers crossed this doesn't cause any edge cases.
*As a consequence of the above point, there's now a function in p_mobj.c/h that returns an object's internal gravity - seperated out from the logic of P_CheckGravity, which really didn't need to be so monolithic. Multiply by global gravity to get the thrust. This should probably be available to Lua somehow, but I have absolutely no idea where to start with that. Wolfs, maybe?
Non-comprehensive test file available at /toaster/slptst3.wad on the ftp.
* -lSDL2_mixer is already added to SDL_LDFLAGS by default, unless NOMIXER=1 is set
* -DSDLMAIN should also be added to OPTS by default for MINGW=1 builds, unless NOSDLMAIN=1 is set
NiGHTS hotfix
Fixes the following issues relating to playing as NiGHTS Super Sonic that apparently popped up between 2.1.14 and next (mostly due to the changes to SRB2's trig stuff it seems):
* Super Sonic drifts to the side at some angles around an axis, and is unable to go directly upwards or downwards as a result
* Drilling to the side when on the ground causes the drill sound to constantly restart
* CEZS's start not actually being lined up properly with the first axis means the player is not able to go backwards along the track (because the player is not actually aligned with the track properly, preventing you from touching the attached line transfer)
* trying to hug some walls such as the tall wall before the library section of CEZS allows Super Sonic to go through them
These fixes needs proper testing before this branch can be merged in, in case they accidentally break other things as a result or something.
See merge request !71
Basically I kind of worked around any potential trig inaccuracies by not using the player position directly for setting momx/momy. This way, if player->angle_pos == player->old_angle_pos, momx/momy are zero
