diff -r 86468a71dd73 -r e7ddb52facd3 src/scene.c
--- a/src/scene.c	Mon Mar 04 21:16:46 2024 +0100
+++ b/src/scene.c	Wed Mar 06 23:08:03 2024 +0100
@@ -32,9 +32,6 @@
 
 #include <assert.h>
 
-#define node_layout_ \
-    offsetof(AscSceneNode, parent), offsetof(AscSceneNode, children), \
-    offsetof(AscSceneNode, prev), offsetof(AscSceneNode, next)
 #define child_list_off_ \
     offsetof(AscSceneNode, children), offsetof(AscSceneNode, next)
 
@@ -61,13 +58,22 @@
     // skip the root node deliberately, we know it's just the container
     cxIteratorNext(iter);
 
-    // draw the children
+    // update the children
     cx_foreach(AscSceneNode*, node, iter) {
+        // execute behaviors, first
+        AscBehaviorNode *behavior = node->behaviors;
+        while (behavior) {
+            behavior->func(node);
+            behavior = behavior->next;
+        }
+
+        // check if geometry needs update
         if (node->need_update && node->update_func != NULL) {
             node->need_update = false;
             asc_transform_copy(node->transform, node->parent->transform);
             node->update_func(node);
         }
+
         // TODO: don't visit the tree for drawing, visit the render groups
         if (node->draw_func != NULL) {
             node->draw_func(node);
@@ -102,9 +108,45 @@
 }
 
 void asc_scene_node_link(AscSceneNode * restrict parent, AscSceneNode * restrict node) {
-    cx_tree_link(parent, node, node_layout_);
+    cx_tree_link(
+            parent, node,
+            offsetof(AscSceneNode, parent),
+            offsetof(AscSceneNode, children),
+            offsetof(AscSceneNode, prev),
+            offsetof(AscSceneNode, next)
+    );
 }
 
 void asc_scene_node_unlink(AscSceneNode *node) {
-    cx_tree_unlink(node, node_layout_);
-}
\ No newline at end of file
+    cx_tree_unlink(
+            node,
+            offsetof(AscSceneNode, parent),
+            offsetof(AscSceneNode, children),
+            offsetof(AscSceneNode, prev),
+            offsetof(AscSceneNode, next)
+    );
+}
+
+AscBehaviorNode *asc_scene_add_behavior(AscSceneNode *node, asc_scene_update_func behavior) {
+    AscBehaviorNode *behavior_node = calloc(1, sizeof(AscBehaviorNode));
+    behavior_node->func = behavior;
+    cx_tree_link(
+            node,
+            behavior_node,
+            offsetof(AscBehaviorNode, parent),
+            offsetof(AscSceneNode, behaviors),
+            offsetof(AscBehaviorNode, prev),
+            offsetof(AscBehaviorNode, next)
+    );
+    return behavior_node;
+}
+
+void asc_scene_remove_behavior(AscBehaviorNode *node) {
+    cx_tree_unlink(
+            node,
+            offsetof(AscBehaviorNode, parent),
+            offsetof(AscSceneNode, behaviors),
+            offsetof(AscBehaviorNode, prev),
+            offsetof(AscBehaviorNode, next)
+    );
+}