Disable small area flow compensation on first layer (Fixes SoftFever#…

…4617) (SoftFever#5838)

Co-authored-by: SoftFever <softfeverever@gmail.com>

src/libslic3r/GCode.cpp

@@ -5442,7 +5442,8 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
                         continue;
                     path_length += line_length;
                     auto dE = e_per_mm * line_length;
-                    if (m_small_area_infill_flow_compensator && m_config.small_area_infill_flow_compensation.value) {
+                    if (!this->on_first_layer() && m_small_area_infill_flow_compensator
+                            && m_config.small_area_infill_flow_compensation.value) {
                         auto oldE = dE;
                         dE = m_small_area_infill_flow_compensator->modify_flow(line_length, dE, path.role());
 
@@ -5482,7 +5483,8 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
                             if (line_length < EPSILON)
                                 continue;
                             auto dE = e_per_mm * line_length;
-                            if (m_small_area_infill_flow_compensator  && m_config.small_area_infill_flow_compensation.value) {
+                            if (!this->on_first_layer() && m_small_area_infill_flow_compensator
+                                    && m_config.small_area_infill_flow_compensation.value) {
                                 auto oldE = dE;
                                 dE = m_small_area_infill_flow_compensator->modify_flow(line_length, dE, path.role());
 
@@ -5505,7 +5507,8 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
                             continue;
                         const Vec2d center_offset = this->point_to_gcode(arc.center) - this->point_to_gcode(arc.start_point);
                         auto dE = e_per_mm * arc_length;
-                        if (m_small_area_infill_flow_compensator && m_config.small_area_infill_flow_compensation.value) {
+                        if (!this->on_first_layer() && m_small_area_infill_flow_compensator
+                                && m_config.small_area_infill_flow_compensation.value) {
                             auto oldE = dE;
                             dE = m_small_area_infill_flow_compensator->modify_flow(arc_length, dE, path.role());
 
@@ -5593,7 +5596,8 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
                 last_set_speed = new_speed;
             }
             auto dE = e_per_mm * line_length;
-            if (m_small_area_infill_flow_compensator  && m_config.small_area_infill_flow_compensation.value) {
+            if (!this->on_first_layer() && m_small_area_infill_flow_compensator
+                     && m_config.small_area_infill_flow_compensation.value) {
                 auto oldE = dE;
                 dE = m_small_area_infill_flow_compensator->modify_flow(line_length, dE, path.role());