aboutsummaryrefslogtreecommitdiff
path: root/src/phys/body.odin
blob: 3c7459724a39ea1ab6aeebdca1540e9eee643569 (plain)
1
2
3
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
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
package phys

import "core:math"
import "core:math/linalg"
import hm "core:container/handle_map"

Vec2 :: [2]f32

Rect :: struct {
  start: Vec2,
  size: Vec2,
}

Layer :: enum (u16) {
  Hard, // hard collisions; don't let bodies intersect at all. default
  Soft, // soft collisions; push away other bodies with a force
  Enemy, // enemy hitboxes
  Player, // player hitboxes
  Enemy_Projectile,
  Player_Projectile,
}

Layer_Set :: bit_set[Layer;u16]

Collision_Type :: enum (u8) {
  Up,
  Down,
  Right,
  Left,
  Horizontal,
  Vertical,
}

Raycast :: struct {
  start: Vec2,
  end: Vec2,
  mask: Layer_Set,
}

Raycast_Collision :: struct {
  body: Body_Handle,
  enter: Vec2,
  exit: Vec2,
}

Body :: struct {
  handle: Body_Handle,
  udata: rawptr,
  bin_idx: i32,
  rect: Rect,
  active: bool,
  pos: Vec2,
  vel: Vec2,
  collisions: bit_set[Collision_Type;u8],
  layers: Layer_Set,
  mask: Layer_Set,
}

@(require_results)
make_body :: proc(
  rect: Rect,
  layers := Layer_Set{.Hard},
  mask := Layer_Set{.Hard},
) -> Body_Handle {
  b := Body {
    rect   = rect,
    layers = layers,
    mask   = mask,
    active = true,
    udata  = nil,
  }
  return add_body(b)
}

@(require_results)
make_raycast :: #force_inline proc(
  start: Vec2,
  end: Vec2,
  mask := Layer_Set{.Hard},
) -> Raycast {
  return Raycast{
    start,
    end,
    mask,
  }
}

@(require_results)
aabb_hori :: proc(a: Rect, b: Rect) -> bool {
  return a.start.x < b.start.x + b.size.x && b.start.x < a.start.x + a.size.x
}

@(require_results)
aabb_vert :: proc(a: Rect, b: Rect) -> bool {
  return a.start.y < b.start.y + b.size.y && b.start.y < a.start.y + a.size.y
}

@(require_results)
aabb :: proc(a: Rect, b: Rect) -> bool {
  return aabb_hori(a, b) && aabb_vert(a, b)
}

@(require_results)
point_aabb_hori :: proc(r: Rect, p: Vec2) -> bool {
  return r.start.x < p.x && r.start.x + r.size.x > p.x
}

@(require_results)
point_aabb_vert :: proc(r: Rect, p: Vec2) -> bool {
  return r.start.y < p.y && r.start.y + r.size.y > p.y
}

@(require_results)
point_aabb :: proc(r: Rect, p: Vec2) -> bool {
  return point_aabb_hori(r, p) && point_aabb_vert(r, p)
}

@(require_results)
raycast_to_aabb :: proc(
  rc: Raycast,
  body: Body,
) -> (collision := Raycast_Collision{}, collided := false) {
  body_min := body.pos + body.rect.start
  body_max := body_min + body.rect.size

  rc_dir_to_body := (body_min + body_max) * 0.5 - rc.start
  rc_dir := linalg.normalize0(rc.end - rc.start)

  // Don't consider bodies behind the ray
  if linalg.dot(rc_dir_to_body, rc_dir) < 0 {
    return
  }

  near := -math.INF_F32
  far := math.INF_F32

  dir_inv := 1.0 / rc_dir

  tx_near := (body_min.x - rc.start.x) * dir_inv.x
  tx_far := (body_max.x - rc.start.x) * dir_inv.x
  
  near = max(near, min(tx_far, tx_near))
  far = min(far, max(tx_far, tx_near))

  ty_near := (body_min.y - rc.start.y) * dir_inv.y
  ty_far := (body_max.y - rc.start.y) * dir_inv.y
  
  near = max(near, min(ty_far, ty_near))
  far = min(far, max(ty_far, ty_near))

  collision.body = body.handle
  collision.enter = rc.start + rc_dir * near
  collision.exit = rc.start + rc_dir * far

  rc_len := linalg.length2(rc.end - rc.start)
  rc_dist_to_body := linalg.length2(rc.start - collision.enter)

  collided = far >= near && rc_dist_to_body <= rc_len

  return
}

@(require_results)
get_velocity :: proc(h: Body_Handle) -> Vec2 {
  return hm.get(&world.bodies, h).vel
}

set_velocity :: proc(h: Body_Handle, vel: Vec2) {
  hm.get(&world.bodies, h).vel = vel
}

@(require_results)
get_position :: proc(h: Body_Handle) -> Vec2 {
  return hm.get(&world.bodies, h).pos
}

set_position :: proc(h: Body_Handle, new_pos: Vec2) {
  b := hm.get(&world.bodies, h) 

  prev_bin := _hash_bin(_world_to_bin(b.pos + b.rect.start))
  res_bin := _hash_bin(_world_to_bin(new_pos + b.rect.start))

  if prev_bin != res_bin {
    _remove_from_bins(b^)
    b.pos = new_pos
    _add_to_bins(b)
  } else {
    b.pos = new_pos
  }
}

@(require_results)
get_collisions :: proc(h: Body_Handle) -> bit_set[Collision_Type;u8] {
  return hm.get(&world.bodies, h).collisions
}

@(require_results)
get_rect :: proc(h: Body_Handle) -> Rect {
  return hm.get(&world.bodies, h).rect
}

@(require_results)
get_layers :: proc(h: Body_Handle) -> Layer_Set {
  return hm.get(&world.bodies, h).layers
}

@(require_results)
get_mask :: proc(h: Body_Handle) -> Layer_Set {
  return hm.get(&world.bodies, h).mask
}

@(require_results)
get_udata :: proc(h: Body_Handle) -> rawptr {
  return hm.get(&world.bodies, h).udata
}

set_udata :: proc(h: Body_Handle, udata: rawptr) {
  hm.get(&world.bodies, h).udata = udata
}