diff -r 25fb39f8863a -r 0ce353485509 src/scene.c
--- a/src/scene.c	Sun Oct 06 19:45:34 2024 +0200
+++ b/src/scene.c	Sun Oct 06 20:49:43 2024 +0200
@@ -32,6 +32,7 @@
 
 #include <cx/linked_list.h>
 #include <cx/array_list.h>
+#include <cx/tree.h>
 #include <cx/utils.h>
 
 #include "ascension/shader.h"
@@ -39,7 +40,24 @@
 
 #include <assert.h>
 
-// TODO: move to a sprite.c
+static CxTreeIterator asc_scene_node_iterator(
+        AscSceneNode *node,
+        bool visit_on_exit
+) {
+    return cx_tree_iterator(
+            node, visit_on_exit,
+            offsetof(AscSceneNode, children),
+            offsetof(AscSceneNode, next)
+    );
+}
+
+static CxTreeVisitor asc_scene_node_visitor(AscSceneNode *node) {
+    return cx_tree_visitor(node,
+            offsetof(AscSceneNode, children),
+            offsetof(AscSceneNode, next)
+    );
+}
+
 static void asc_sprite_draw(AscSprite const *node) {
     // Obtain shader
     AscShaderSprite *shader = ASC_SHADER_SPRITE;
@@ -58,7 +76,7 @@
     asc_primitives_draw_plane();
 }
 
-void asc_scene_draw(AscScene scene, asc_recti viewport, AscCamera *camera) {
+void asc_scene_draw(AscSceneNode *root, asc_recti viewport, AscCamera *camera) {
     // create render groups
     CxList *render_group[ASC_RENDER_GROUP_COUNT];
     cx_for_n(i, ASC_RENDER_GROUP_COUNT) {
@@ -66,7 +84,7 @@
     }
 
     // skip the root node deliberately, we know it's just the container
-    CxTreeVisitor iter = cxTreeVisit(scene);
+    CxTreeVisitor iter = asc_scene_node_visitor(root);
     cxIteratorNext(iter);
 
     // update the children and add them to the render groups
@@ -110,7 +128,7 @@
             asc_mat4f_mulst(
                     node->world_transform,
                     node->transform,
-                    asc_scene_node_parent(node)->world_transform
+                    node->parent->world_transform
             );
         }
 
@@ -168,55 +186,54 @@
 
 AscSceneNode *asc_scene_node_empty(void) {
     AscSceneNode *node = calloc(1, sizeof(AscSceneNode));
+    node->free_func = (asc_scene_free_func) free;
     node->scale.x = node->scale.y = node->scale.z = 1;
     asc_transform_identity(node->transform);
     asc_transform_identity(node->world_transform);
     return node;
 }
 
-void asc_scene_node_destructor(AscSceneNode *node) {
-    if (node->behaviors != NULL) {
-        cxListDestroy(node->behaviors);
-    }
-    if (node->free_func != NULL) {
-        node->free_func(node);
-    } else {
-        free(node);
+void asc_scene_node_free(AscSceneNode *node) {
+    if (node == NULL) return;
+
+    // remove this node from its parent
+    asc_scene_node_unlink(node);
+
+    // free the entire subtree
+    CxTreeIterator iter = asc_scene_node_iterator(node, true);
+    cx_foreach(AscSceneNode*, child, iter) {
+        if (!iter.exiting) continue;
+        if (child->behaviors != NULL) {
+            cxListDestroy(child->behaviors);
+        }
+        if (child->free_func != NULL) {
+            child->free_func(child);
+        } else {
+            free(child);
+        }
     }
 }
 
-AscScene asc_scene_create(void) {
-    AscSceneNode *root = asc_scene_node_empty();
-    AscScene scene = cxTreeCreateWrapped(
-            cxDefaultAllocator, root,
-            cx_tree_node_base_layout
+void asc_scene_node_link(AscSceneNode * restrict parent, AscSceneNode * restrict node) {
+    cx_tree_link(
+            parent, node,
+            offsetof(AscSceneNode, parent),
+            offsetof(AscSceneNode, children),
+            offsetof(AscSceneNode, last_child),
+            offsetof(AscSceneNode, prev),
+            offsetof(AscSceneNode, next)
     );
-    root->scene = scene;
-    scene->simple_destructor = (cx_destructor_func) asc_scene_node_destructor;
-    return scene;
-}
-
-void asc_scene_destroy(AscScene scene) {
-    cxTreeDestroy(scene);
 }
 
-void asc_scene_node_add(AscSceneNode * restrict parent, AscSceneNode * restrict node) {
-    assert(node->scene == NULL || node->scene == parent->scene);
-    cxTreeSetParent(parent->scene, parent, node);
-    CxTreeVisitor visitor = cxTreeVisitSubtree(parent->scene, node);
-    cx_foreach(AscSceneNode *, n, visitor) {
-        n->scene = parent->scene;
-    }
-    asc_node_update_transform(node);
-}
-
-void asc_scene_node_remove(AscSceneNode *node) {
-    if (node->scene == NULL) return;
-    cxTreeRemoveSubtree(node->scene, node);
-    CxTreeVisitor visitor = cxTreeVisitSubtree(node->scene, node);
-    cx_foreach(AscSceneNode *, n, visitor) {
-        n->scene = NULL;
-    }
+void asc_scene_node_unlink(AscSceneNode *node) {
+    cx_tree_unlink(
+            node,
+            offsetof(AscSceneNode, parent),
+            offsetof(AscSceneNode, children),
+            offsetof(AscSceneNode, last_child),
+            offsetof(AscSceneNode, prev),
+            offsetof(AscSceneNode, next)
+    );
 }
 
 void asc_scene_add_behavior(
@@ -248,14 +265,7 @@
         return;
     }
 
-    // if node is not part of a scene, just mark it and return
-    if (node->scene == NULL) {
-        asc_set_flag(node->flags, ASC_SCENE_NODE_UPDATE_TRANSFORM);
-        return;
-    }
-
-    // creating the iterator this way saves us from needing scene as parameter
-    CxTreeIterator iter = cxTreeIterateSubtree(node->scene, node, false);
+    CxTreeIterator iter = asc_scene_node_iterator(node, false);
     cx_foreach(AscSceneNode*, n, iter) {
         if (asc_test_flag(n->flags, ASC_SCENE_NODE_UPDATE_TRANSFORM)) {
             cxTreeIteratorContinue(iter);