fix: PA pattern calibration over-retracts with absolute E distances (#14473)

src/libslic3r/calib.cpp

@@ -771,6 +771,7 @@ CustomGCode::Info CalibPressureAdvancePattern::generate_custom_gcodes(const Dyna
         }
     }
 
+    gcode << m_writer.reset_e();
     gcode << m_writer.set_pressure_advance(m_params.start);
     gcode << "; end pressure advance pattern for layer\n";
 

tests/libslic3r/test_calib.cpp

@@ -1,5 +1,9 @@
 #include <catch2/catch_all.hpp>
 
+#include <algorithm>
+#include <sstream>
+#include <string>
+
 #include "libslic3r/calib.hpp"
 #include "libslic3r/Model.hpp"
 #include "libslic3r/TriangleMesh.hpp"
@@ -38,3 +42,69 @@ TEST_CASE("Zero calibration line width resolves to a positive default", "[Calib]
     REQUIRE(pattern.line_width() > 0.);
     REQUIRE(pattern.line_width_first_layer() > 0.);
 }
+
+namespace {
+
+struct EndState { double final_e; double max_e; };
+
+EndState simulate_absolute_e(const std::string &gcode)
+{
+    double final_e = 0.;
+    double max_e   = 0.;
+
+    std::istringstream lines(gcode);
+    std::string        line;
+    while (std::getline(lines, line)) {
+        std::istringstream words(line);
+        std::string        op;
+        if (!(words >> op))
+            continue;
+        if (op != "G1" && op != "G0" && op != "G92")
+            continue;
+
+        std::string word;
+        while (words >> word) {
+            if (word.size() >= 2 && word[0] == 'E') {
+                final_e = std::stod(word.substr(1));
+                max_e   = std::max(max_e, final_e);
+                break;
+            }
+        }
+    }
+
+    return {final_e, max_e};
+}
+
+} // namespace
+
+TEST_CASE("PA pattern resets the extruder after the final layer in absolute E mode", "[Calib][Regression]")
+{
+    DynamicPrintConfig config = DynamicPrintConfig::full_print_config();
+    config.set_deserialize_strict({
+        {"use_relative_e_distances", "0"},
+        {"line_width", "0.45"},
+        {"initial_layer_line_width", "0.45"},
+    });
+
+    Model model;
+    model.add_object("cube", "", make_cube(20, 20, 20))->add_instance();
+
+    Calib_Params params;
+    params.mode  = CalibMode::Calib_PA_Pattern;
+    params.start = 0.;
+    params.end   = 0.08;
+    params.step  = 0.002;
+
+    CalibPressureAdvancePattern pattern(params, config, /* is_bbl_machine */ false, *model.objects.front(), Vec3d(0, 0, 0));
+    const CustomGCode::Info     info = pattern.generate_custom_gcodes(config, /* is_bbl_machine */ false, *model.objects.front(),
+                                                                      Vec3d(0, 0, 0));
+
+    std::string gcode;
+    for (const CustomGCode::Item &item : info.gcodes)
+        gcode += item.extra;
+
+    const EndState state = simulate_absolute_e(gcode);
+
+    REQUIRE(state.max_e > 1.);
+    REQUIRE_THAT(state.final_e, Catch::Matchers::WithinAbs(0., 1e-9));
+}