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package phys
import "core:log"
import "core:math"
import rl "vendor:raylib"
BIN_COUNT :: 2056
BIN_SIZE :: 64
Body_Handle :: u32
world: struct {
handles: [dynamic]u32,
unused_handles: [dynamic]Body_Handle,
bodies: [dynamic]Body,
bins: [BIN_COUNT][dynamic]Body_Handle,
}
destroy_world :: proc() {
for bin in world.bins {
delete(bin)
}
delete(world.handles)
delete(world.unused_handles)
delete(world.bodies)
}
@(private="file")
hash_bin :: proc(x: i32, y: i32) -> u32 {
return transmute(u32)((x * 73856093) ~ (y * 19349663))
}
@(private="file")
world_to_bin :: proc(point: Vec2) -> (i32, i32) {
return \
i32(math.floor(point.x / BIN_SIZE)),
i32(math.floor(point.y / BIN_SIZE))
}
@(private="file")
get_surrounding_bins :: proc(
pos: Vec2,
allocator := context.temp_allocator,
) -> []^[dynamic]Body_Handle {
neighbors := make([]^[dynamic]Body_Handle, 9, allocator)
center_x, center_y := world_to_bin(pos)
idx := 0
for offset_x in -1..=1 {
for offset_y in -1..=1 {
bin_idx := hash_bin(center_x + i32(offset_x), center_y + i32(offset_y))
bin := &world.bins[bin_idx % BIN_COUNT]
neighbors[idx] = bin
idx += 1
}
}
return neighbors
}
@(private="file")
find_bin :: proc(b: Body) -> ^[dynamic]Body_Handle {
bin_x, bin_y := world_to_bin(b.pos + b.rect.start)
return &world.bins[hash_bin(bin_x, bin_y) % BIN_COUNT]
}
@(private="file")
add_to_bins :: proc(b: Body) {
bin := find_bin(b)
idx := i32(len(bin))
append(bin, b.handle)
world.bodies[bin[idx]].bin_idx = idx
}
@(private="file")
remove_from_bins :: proc(b: Body) {
bin := find_bin(b)
assert(bin[b.bin_idx] == b.handle)
last := pop(bin)
if last != b.handle {
bin[b.bin_idx] = last
world.bodies[last].bin_idx = b.bin_idx
}
}
get_body :: proc(h: Body_Handle) -> ^Body {
return &world.bodies[world.handles[h]]
}
add_body :: proc(b: Body) -> (Body_Handle, ^Body) {
handle: Body_Handle
if b.rect.size.x > BIN_SIZE || b.rect.size.y > BIN_SIZE {
log.warnf("Body size is too big (%vx%v)", b.rect.size.x, b.rect.size.y)
}
if len(world.unused_handles) > 0 {
handle = pop(&world.unused_handles)
} else {
handle = cast(Body_Handle)len(world.handles)
append(&world.handles, 0)
}
world.handles[handle] = u32(len(world.bodies))
append(&world.bodies, b)
body := &world.bodies[world.handles[handle]]
body.handle = handle
add_to_bins(body^)
return handle, body
}
remove_body :: proc(h: Body_Handle) {
b := get_body(h)
remove_from_bins(b^)
last := pop(&world.bodies)
if last.handle != h {
world.bodies[h] = last
world.handles[last.handle] = world.handles[h]
}
append(&world.unused_handles, b.handle)
}
update_body :: proc(h: Body_Handle) {
dt := rl.GetFrameTime()
b := get_body(h)
res_pos := b.pos + b.vel * dt
rect := b.rect
rect.start += b.pos
res_rect := b.rect
res_rect.start += res_pos
bin_list := get_surrounding_bins(res_rect.start)
b.collisions = {}
total_len := 0
for bin in bin_list {
total_len += len(bin)
for c_h in bin {
if c_h == h {
continue
}
c := get_body(c_h)
c_rect := c.rect
c_rect.start += c.pos
if aabb(res_rect, c_rect) {
if aabb_hori(rect, c_rect) {
if b.vel.y > 0 {
res_pos.y = c_rect.start.y - b.rect.size.y - b.rect.start.y
b.collisions += {.DOWN}
} else {
res_pos.y = c_rect.start.y + c_rect.size.y - b.rect.start.y
b.collisions += {.UP}
}
b.collisions += {.VERTICAL}
} else if aabb_vert(rect, c.rect) {
if b.vel.x > 0 {
res_pos.x = c_rect.start.x - b.rect.size.x - b.rect.start.x
b.collisions += {.LEFT}
} else {
res_pos.x = c_rect.start.x + c_rect.size.x - b.rect.start.x
b.collisions += {.RIGHT}
}
b.collisions += {.HORIZONTAL}
}
}
}
}
if .HORIZONTAL in b.collisions {
b.vel.x = 0
}
if .VERTICAL in b.collisions {
b.vel.y = 0
}
b.pos = res_pos
prev_bin := hash_bin(world_to_bin(b.pos + b.rect.start))
res_bin := hash_bin(world_to_bin(res_pos + b.rect.start))
if prev_bin != res_bin {
remove_from_bins(b^)
add_to_bins(b^)
}
}
|
