From 82079ea16cdd6721ad6da3fa60ea0162bc7413bd Mon Sep 17 00:00:00 2001
From: Noisyfox <timemanager.rick@gmail.com>
Date: Sun, 28 Sep 2025 11:07:28 +0800
Subject: [PATCH] Allow negative vector index

---
 src/libslic3r/PlaceholderParser.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libslic3r/PlaceholderParser.cpp b/src/libslic3r/PlaceholderParser.cpp
index 12816a0eae..b83ecbac0e 100644
--- a/src/libslic3r/PlaceholderParser.cpp
+++ b/src/libslic3r/PlaceholderParser.cpp
@@ -1014,7 +1014,7 @@ namespace client
                 if (! opt.opt->is_vector())
                     ctx->throw_exception("Cannot index a scalar variable", opt.it_range);
                 if (index < 0)
-                    ctx->throw_exception("Referencing a vector variable with a negative index", opt.it_range);
+                    index = 0; // Orca: fallback to first element if index < 0, this matches the behavior of BambuStudio
                 output = opt;
                 output.index = index;
             } else