respawn.titanfall.Brush's final unknown member

[snake-biscuits]

typedef struct { float x, y, z; } Vector3;

struct Brush {
    Vector3  origin;
#ifdef REXX_STRUCTS:
    uint8_t  non_axial[2];
#elif
    uint8_t  unknown_non_axial;  /* <-- This guy right here; currently causing collision bugs */
    uint8_t  num_plane_offsets;
#endif /* REXX_STRUCTS */
    int16_t  index;
    Vector3  extents;
    int32_t  brush_side_offset;
};

[snake-biscuits]

>>> import bsp_tool
>>> bsp = bsp_tool.load_bsp("E:/Mod/TitanfallOnline/maps/mp_box.bsp")
>>> bsp.CM_BRUSHES[19]
Brush(origin=vec3(2384.0, 1020.0, -1468.0),
          unknown_non_axial=2, num_plane_offsets=4, index=19,
          extents=vec3(320.0, 4.0, 68.0), brush_side_offset=0)
>>> b19 = bsp.get_brush_sides(19)
>>> len(b19["properties"])
10  # 6 + 4? that's excessive

mp_box.CM_BRUSHES[19] is one of these walls on the "VDU" boxes (where faction leaders livestream to the troops)

(not the selected one! I guessed poorly taking the screenshot)

>>> {print(pl, pr) for pl, pr in [*zip(b19["planes"], b19["properties"])][6:]}
(vec3( 0.7071067690849304, 0.7071067690849304,  0.0),  2183.545654296875)   <BrushSideProperty.UNKNOWN_FLAG|1: 32769>
(vec3(-0.7071067690849304, 0.7071067690849304, -0.0), -1187.9393310546875)  <BrushSideProperty.UNKNOWN_FLAG|1: 32769>
(vec3( 0.7071068286895752, 0.7071068286895752, -0.0),  2183.5458984375)     <BrushSideProperty.DISCARD|1: 16385>
(vec3(-0.7071068286895752, 0.7071068286895752, -0.0), -1187.939453125)      <BrushSideProperty.DISCARD|1: 16385>
{None}

[snake-biscuits]

Checking which axial sides are discarded, we can see that this brush is actually one of the 4 northern/southern walls

>>> vec3 = bsp_tool.branches.vector.vec3
>>> axes = {vec3(x=1): "X+", vec3(x=-1): "X-", vec3(y=1): "Y+", vec3(y=-1): "Y-", vec3(z=1): "Z+", vec3(z=-1): "Z-"}
>>> {print(axes[pl[0]], pr) for pl, pr in [*zip(b19["planes"], b19["properties"])][:6]}
X+ BrushSideProperty.DISCARD|1
X- BrushSideProperty.DISCARD|1
Y+ BrushSideProperty.2|1
Y- BrushSideProperty.1
Z+ BrushSideProperty.UNKNOWN_FLAG|1
Z- BrushSideProperty.UNKNOWN_FLAG|1
{None}

[snake-biscuits]

The way BrushSideProperty.UNKNOWN_FLAG appears here makes me think it's used on faces that abut other brushes
(and would never be touched / seen)
Ignoring physics on these sides could limit "pixel walking"

Pixel walking occurs when a rounding error allows a player to stand on the unexposed of a brush, whilst against a wall

  P|__ SOLID WALL
 __|   ^ ABUTTING BRUSHSIDE

[snake-biscuits]

Brush[19] was selected w/ the following filter for non-axial brushes:

>>> [(i, b.unknown_non_axial, b.num_plane_offsets) for i, b in enumerate(bsp.CM_BRUSHES) if b.unknown_non_axial != 0]
[(19, 2, 4), (20, 2, 4), (22, 2, 4), (23, 2, 4), (24, 2, 4), (26, 2, 4), (28, 2, 4), (29, 2, 4),
 (34, 1, 1), (46, 1, 1), (57, 1, 1), (58, 1, 1)]

19 to 29 are VDU walls; 34 to 58 are ramps in the playable area of mp_box

[snake-biscuits]

>>> b34 = bsp.get_brush_sides(34)
>>> {print(axes[pl[0]], pr) for pl, pr in [*zip(b34["planes"], b34["properties"])][:6]}
X+ BrushSideProperty.4|2|1
X- BrushSideProperty.4|2|1
Y+ BrushSideProperty.4|2|1
Y- BrushSideProperty.4|2|1
Z+ BrushSideProperty.4|2|1
Z- BrushSideProperty.DISCARD|4|2|1
{None}
>>> {print(pl, pr) for pl, pr in [*zip(b34["planes"], b34["properties"])][6:]}
(vec3(-0.0, 0.5462678074836731, -0.8376106023788452), 636.2927856445312) BrushSideProperty.4|2|1
{None}

(I should really mask out the TEXTUREDATA index in properties here)

(34, 1, 1)
No masks on the non-axial planes here? is unknown_non_axial counting non-discarded non-axial sides?, or discarded axial sides?

[snake-biscuits]

We need to find a brush with non-ambiguous counts, and assert those counts are consistent across all brushes

[snake-biscuits]

Looking for more diverse brushes, r2_rise has a relatively low brushside count (~137K)

>>> r2_rise = bsp_tool.load_bsp("E:/Mod/Titanfall2/maps/mp_rise.bsp")
>>> {print(f"{L:<32} {getattr(r2_rise, L)!r}") for L, h in r2_rise.headers.items() if h.length != 0 and "BRUSH" in L}
CM_BRUSHES                       <BspLump(7017 Brush) at 0x0000029C006C9A00>
CM_BRUSH_SIDE_PLANE_OFFSETS      <BasicBspLump(95166 UnsignedShorts) at 0x0000029C006C9A90>
CM_BRUSH_SIDE_PROPERTIES         <BasicBspLump(137268 BrushSideProperty) at 0x0000029C006C9AF0>
CM_BRUSH_SIDE_TEXTURE_VECTORS    <BspLump(137268 TextureVector) at 0x0000029C006C9B50>
{None}
>>> bis = [(i, b.unknown_non_axial, b.num_plane_offsets) for i, b in enumerate(r2_rise.CM_BRUSHES)
           if b.unknown_non_axial != 0]
>>> import collections
>>> dd = collections.defaultdict(set)
>>> for bi, una, npo in bis:
...     dd[(una, npo)].add(bi)
...
>>> len(dd)
165  # non_axial values to compare

Listing all 165 non-axial values used in r2_rise

>>> dd2 = collections.defaultdict(set)
>>> for a, b in dd.keys():
...     dd2[a].add(b)
...
>>> {print(a, sorted(dd2[a])) for a in sorted(dd2)}
# unknown_non_axial | [num_plane_offsets]
1  [3, 4, 5, 6, 7, 8, 9, 10, 11, 13]
2  [4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 23, 28]
3  [6, 7, 8, 10, 13, 14, 19, 21, 23, 24, 25, 27, 28, 31]
4  [4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33]
5  [8, 9, 10, 11, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 31, 32, 33, 34, 35,
    36, 37, 38, 39, 41, 42, 43]
6  [12, 14, 16, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
    40, 41, 42, 43, 44, 46]
7  [35, 37, 39, 40]
8  [16, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 29, 30, 32, 33, 34, 36, 37, 38, 39, 40, 41, 43]
10 [21, 25, 30, 41, 42, 44]

[snake-biscuits]

non_axial_unknown can be > 6!, so it doesn't refer to axial flags (at least, not exculsively)
What about the theory:

non_axial_unknown == len([p for p in bss["properties"][6:] if not (p & BrushSideProperty.DISCARD)])

Time to test.

[snake-biscuits]

Well,

>>> dd[(1, 13)]  # (unknown, num_plane_offsets)
{774}
>>> b774 = r2_rise.get_brush_sides(774)
>>> {print(pl, pr) for pl, pr in [*zip(b774["planes"], b774["properties"])][6:]}
(vec3(0.468524307012558, -0.8834506273269653, -0.0), -343.79888916015625) BrushSideProperty.32|4|1
(vec3(0.468524307012558, -0.8834506869316101, -0.0), -343.798828125) BrushSideProperty.DISCARD|32|4|1
(vec3(-0.7071067690849304, 0.7071067690849304, -0.0), 627.9112548828125) BrushSideProperty.DISCARD|32|4|1
(vec3(-0.515497624874115, -0.8568909764289856, -0.0), 1621.929443359375) BrushSideProperty.DISCARD|32|4|1
(vec3(0.9704253673553467, 0.24140149354934692, -0.0), -3048.445556640625) BrushSideProperty.DISCARD|32|4|1
(vec3(-0.883446216583252, -0.46853259205818176, -0.0), 2099.63037109375) BrushSideProperty.DISCARD|32|4|1
(vec3(0.46853259205818176, -0.883446216583252, -0.0), -343.8275146484375) BrushSideProperty.DISCARD|32|4|1
(vec3(0.883446216583252, 0.46853259205818176, -0.0), -3055.82373046875) BrushSideProperty.DISCARD|32|4|1
(vec3(-0.46853259205818176, 0.883446216583252, -0.0), -51.96533203125) BrushSideProperty.DISCARD|32|4|1
(vec3(-0.996008038520813, -0.08926443755626678, -0.0), 2068.652587890625) BrushSideProperty.DISCARD|32|4|1
(vec3(0.08926443755626678, -0.996008038520813, -0.0), 497.328369140625) BrushSideProperty.DISCARD|32|4|1
(vec3(0.996008038520813, 0.08926443755626678, -0.0), -2950.020751953125) BrushSideProperty.DISCARD|32|4|1
(vec3(-0.08926443755626678, 0.996008038520813, -0.0), -943.5399169921875) BrushSideProperty.DISCARD|32|4|1
{None}

NOTE: side plane[7] (2nd in the list) is the same as [6], but rounded differently

[snake-biscuits]

r2_rise passes the test!

>>> r1 = bsp_tool.branches.respawn.titanfall
>>> def test(bsp, brush_index: int) -> bool:
...     brush_sides = bsp.get_brush_sides(brush_index)
...     brush = bsp.CM_BRUSHES[brush_index]
...     return brush.unknown_non_axial == len([p for p in brush_sides["properties"][6:]
                                               if (p & r1.BrushSideProperty.DISCARD) == 0])
...
>>> test(r2_rise, 774)
True
>>> all([test(r2_rise, i) for i, u, npo in bis])
True  # !!!

Now to test all r1, r1o & r2 maps

[snake-biscuits]

>>> import os, fnmatch
>>> r1md = "E:/Mod/Titanfall/maps"
>>> r1omd = "E:/Mod/TitanfallOnline/maps"
>>> r2md = "E:/Mod/Titanfall2/maps"
>>> gd = {"r1": r1md, "r1o": r1omd, "r2": r2md}
>>> maps = {f"{g}/{m[:-4]}": bsp_tool.load_bsp(os.path.join(md, m))
            for g, md in gd.items() for m in fnmatch.filter(os.listdir(md), "*.bsp")}
>>> {m for m, b in maps.items() if any([test(b, i) == False for i in range(len(b.CM_BRUSHES))])}
set()  # all maps pass the test!