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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,
end: Vec2,
mask: Layer_Set,
}
Raycast_Collision :: struct {
body: Body_Handle,
enter: Vec2,
exit: Vec2,
}
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,
}
@(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,
}
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
}
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