diff --git a/include/ui.h b/include/ui.h
new file mode 100644
index 0000000..6403253
--- /dev/null
+++ b/include/ui.h
@@ -0,0 +1,10 @@
+#ifndef UI_H
+#define UI_H
+
+#include "aliases/aliases.h"
+#include "window.h"
+#include <stdbool.h>
+
+bool aabb(const rect_t *rect, i32 x, i32 y);
+
+#endif // !UI_H
diff --git a/src/ui.c b/src/ui.c
new file mode 100644
index 0000000..a5a71ba
--- /dev/null
+++ b/src/ui.c
@@ -0,0 +1,6 @@
+#include "ui.h"
+
+bool aabb(const rect_t *rect, i32 x, i32 y) {
+  return x > rect->topleft.x && x <= rect->topleft.x + rect->w &&
+         y > rect->topleft.y && y <= rect->topleft.y + rect->h;
+}