Follow-up to 6f5813a849e40b1bcae97270a317222dff92f5ec: Recalculate infill surfaces when infill_only_where_needed is enabled while switching from the Lightning infill to another infill or vice versa.

1 files changed, 10 insertions, 1 deletions

diff --git a/src/libslic3r/PrintObject.cpp b/src/libslic3r/PrintObject.cpp
index 5cebbb056..419536bf4 100644
--- a/src/libslic3r/PrintObject.cpp
+++ b/src/libslic3r/PrintObject.cpp
@@ -627,12 +627,21 @@ bool PrintObject::invalidate_state_by_config_options(
             || opt_key == "bottom_fill_pattern"
             || opt_key == "external_fill_link_max_length"
             || opt_key == "fill_angle"
-            || opt_key == "fill_pattern"
             || opt_key == "infill_anchor"
             || opt_key == "infill_anchor_max"
             || opt_key == "top_infill_extrusion_width"
             || opt_key == "first_layer_extrusion_width") {
             steps.emplace_back(posInfill);
+        } else if (opt_key == "fill_pattern") {
+            steps.emplace_back(posInfill);
+
+            const auto *old_fill_pattern = old_config.option<ConfigOptionEnum<InfillPattern>>(opt_key);
+            const auto *new_fill_pattern = new_config.option<ConfigOptionEnum<InfillPattern>>(opt_key);
+            assert(old_infill && new_infill);
+            // We need to recalculate infill surfaces when infill_only_where_needed is enabled, and we are switching from
+            // the Lightning infill to another infill or vice versa.
+            if (m_config.infill_only_where_needed && (new_fill_pattern->value == ipLightning || old_fill_pattern->value == ipLightning))
+                steps.emplace_back(posPrepareInfill);
         } else if (opt_key == "fill_density") {
             // One likely wants to reslice only when switching between zero infill to simulate boolean difference (subtracting volumes),
             // normal infill and 100% (solid) infill.