From dbd16ccd67f5a180bc3a024af209ad5776e8db5e Mon Sep 17 00:00:00 2001
From: jacob <jacob@cagori.com>
Date: Tue, 28 Jan 2025 20:31:52 -0600
Subject: [PATCH] skip space cells at 0

---
 src/space.c | 22 +++++++++++++++++-----
 src/user.c  |  2 +-
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/src/space.c b/src/space.c
index c82b5d83..7ca13fef 100644
--- a/src/space.c
+++ b/src/space.c
@@ -15,6 +15,9 @@ READONLY struct space _g_space_nil = { .valid = false };
  * Space alloc
  * ========================== */
 
+/* NOTE:
+ * The number of buckets determines how often tiles will collide in the spatial hash.
+ * For example, at `num_buckets_sqrt` = 256 (65536 buckets), tiles <1, 1>, <1, 257>, and <257, 257> will collide. */
 struct space *space_alloc(f32 cell_size, u32 num_buckets_sqrt)
 {
     struct arena arena = arena_alloc(GIGABYTE(64));
@@ -68,6 +71,9 @@ INTERNAL i32 cell_coords_to_bucket_index(struct space *space, struct v2i32 cell_
 {
     i32 num_buckets_sqrt = space->num_buckets_sqrt;
 
+    /* Cell pos of 0 is not valid and will be converted to -1 */
+    ASSERT(cell_pos.x != 0 && cell_pos.y != 0);
+
     i32 index_x = cell_pos.x;
     i32 index_y = cell_pos.y;
     /* Offset cell index by -1 since cell pos of 0 is invalid */
@@ -291,13 +297,17 @@ void space_client_release(struct space_client *client)
 
 void space_client_update_aabb(struct space_client *client, struct aabb new_aabb)
 {
-
     struct space *space = space_from_client(client);
     f32 cell_size = space->cell_size;
 
-    struct aabb old_aabb = client->aabb;
-    struct v2i32 old_cell_p0 = world_to_cell_coords(cell_size, old_aabb.p0);
-    struct v2i32 old_cell_p1 = world_to_cell_coords(cell_size, old_aabb.p1);
+    struct v2i32 old_cell_p0 = V2I32(0, 0);
+    struct v2i32 old_cell_p1 = V2I32(0, 0);
+    if (client->first_node) {
+        struct aabb old_aabb = client->aabb;
+        old_cell_p0 = world_to_cell_coords(cell_size, old_aabb.p0);
+        old_cell_p1 = world_to_cell_coords(cell_size, old_aabb.p1);
+    }
+
     struct v2i32 new_cell_p0 = world_to_cell_coords(cell_size, new_aabb.p0);
     struct v2i32 new_cell_p1 = world_to_cell_coords(cell_size, new_aabb.p1);
 
@@ -319,7 +329,7 @@ void space_client_update_aabb(struct space_client *client, struct aabb new_aabb)
     /* Insert new nodes */
     for (i32 y = new_cell_p0.y; y <= new_cell_p1.y; ++y) {
         for (i32 x = new_cell_p0.x; x <= new_cell_p1.x; ++x) {
-            if (x < old_cell_p0.x || x > old_cell_p1.x || y < old_cell_p0.y || y > old_cell_p1.y) {
+            if (x != 0 && y != 0 && (x < old_cell_p0.x || x > old_cell_p1.x || y < old_cell_p0.y || y > old_cell_p1.y)) {
                 /* Cell is outside of old AABB */
                 space_cell_node_alloc(V2I32(x, y), client);
             }
@@ -396,6 +406,8 @@ struct space_client *space_iter_next(struct space_iter *iter)
             if (nextx || nexty) {
                 cell_cur.x += nextx - (span * nexty);
                 cell_cur.y += nexty;
+                cell_cur.x += (cell_cur.x == 0);
+                cell_cur.y += (cell_cur.y == 0);
                 iter->cell_cur = cell_cur;
                 struct space_cell *cell = space_get_cell(space, cell_cur);
                 next_node = cell->first_node;
diff --git a/src/user.c b/src/user.c
index d7bbbd2c..3c29303c 100644
--- a/src/user.c
+++ b/src/user.c
@@ -374,7 +374,7 @@ INTERNAL void queue_game_cmd(struct arena *arena, struct game_cmd_list *list, st
 {
     struct game_cmd_node *node = arena_push_zero(arena, struct game_cmd_node);
     node->cmd = cmd;
-    if (list->first) {
+    if (list->last) {
         list->last->next = node;
     } else {
         list->first = node;