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package phys
import "core:math"
import "core:math/linalg"
import "core:log"
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,
dir: Vec2,
mask: Layer_Set,
}
Body :: struct {
handle: Body_Handle,
bin_idx: i32,
rect: Rect,
active: bool,
pos: Vec2,
vel: Vec2,
collisions: bit_set[Collision_Type;u8],
layers: Layer_Set,
mask: Layer_Set,
}
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,
}
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) -> bool {
body_min := body.pos + body.rect.start
body_max := body_min + body.rect.size
rc_dir_to_body := linalg.normalize0((body_min + body_max) * 0.5 - rc.start)
// Don't consider bodies behind the ray
if linalg.dot(rc_dir_to_body, rc.dir) < 0 {
return false;
}
tmin := -math.INF_F32
tmax := math.INF_F32
dir_inv := 1.0 / rc.dir
tx_min := (body_min.x - rc.start.x) * dir_inv.x
tx_max := (body_max.x - rc.start.x) * dir_inv.x
tmin = max(tmin, min(tx_max, tx_min))
tmax = min(tmax, max(tx_max, tx_min))
ty_min := (body_min.y - rc.start.y) * dir_inv.y
ty_max := (body_max.y - rc.start.y) * dir_inv.y
tmin = max(tmin, min(ty_max, ty_min))
tmax = min(tmax, max(ty_max, ty_min))
return tmax >= tmin
}
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