From 12232deb7a6eccc7639d711759b4edb11378ca54 Mon Sep 17 00:00:00 2001
From: Aleksandr Dobkin <alex@dobk.in>
Date: Mon, 16 Mar 2026 13:48:42 -0700
Subject: [PATCH] Fix z-offset handling for ZAA

---
 src/libslic3r/ContourZ.cpp    | 9 +++------
 src/libslic3r/PrintObject.cpp | 7 ++++---
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/src/libslic3r/ContourZ.cpp b/src/libslic3r/ContourZ.cpp
index 0182b35aad..8eb1a8b5a8 100644
--- a/src/libslic3r/ContourZ.cpp
+++ b/src/libslic3r/ContourZ.cpp
@@ -30,8 +30,6 @@ static double slope_from_normal(const Eigen::Vector3d& normal)
 	return angle_rad;
 }
 
-// const int LINE = 180;
-
 static bool contour_extrusion_path(LayerRegion *region, const sla::IndexedMesh &mesh, ExtrusionPath &path)
 {
 	if (region->region().config().zaa_region_disable) {
@@ -213,14 +211,13 @@ static void contour_extrusion_entity(LayerRegion *region, const sla::IndexedMesh
 }
 
 static void handle_extrusion_collection(LayerRegion *region, const sla::IndexedMesh &mesh, ExtrusionEntityCollection &collection, std::initializer_list<ExtrusionRole> roles) {
-	for (ExtrusionEntity *extr : collection.entities) {
-		// printf("handling extrusion collection %p %p\n", &collection, extr);
-		if (!contains(roles, extr->role())) {
+    for (ExtrusionEntity* extr : collection.entities) {
+        if (!contains(roles, extr->role())) {
 			continue;
 		}
 
 		contour_extrusion_entity(region, mesh, extr);
-	}
+    }
 }
 
 void Layer::make_contour_z(const sla::IndexedMesh &mesh)
diff --git a/src/libslic3r/PrintObject.cpp b/src/libslic3r/PrintObject.cpp
index 12d2d6855b..5dd342eaf9 100644
--- a/src/libslic3r/PrintObject.cpp
+++ b/src/libslic3r/PrintObject.cpp
@@ -28,7 +28,6 @@
 #include <float.h>
 #include <iterator>
 #include <mutex>
-#include <ostream>
 #include <string>
 #include <oneapi/tbb/blocked_range.h>
 #include <oneapi/tbb/concurrent_vector.h>
@@ -731,13 +730,15 @@ void PrintObject::contour_z()
     }
 
     ModelInstance *inst = m_model_object->instances.front();
-    Point center_offset = this->center_offset();
+    Point                    center_offset = this->center_offset();
     Geometry::Transformation trans = inst->get_transformation();
+    double                   z             = trans.get_offset().z() - unscale<double>(this->height()) / 2;
     trans.set_offset(Vec3d(-unscale<double>(center_offset.x()), -unscale<double>(center_offset.y()), 0));
-
     mesh.transform(trans.get_matrix());
 
     sla::IndexedMesh imesh(mesh);
+    imesh.ground_level_offset(-z);
+
     std::mutex mtx;
     size_t completed = 0;
     tbb::parallel_for(