From ab2a2d57253e5f9851e1b82b7309dd0a0b2b95eb Mon Sep 17 00:00:00 2001
From: stew675 <sforster@fastly.com>
Date: Sat, 2 Dec 2023 19:37:33 -0600
Subject: [PATCH] Add zhop to PA pattern (#2952)

The current PA pattern implementation does not lift the nozzle
when moving.  The way the pattern is drawn means that the nozzle
is often dragged over already printed lines, which can pull the
pattern off the bed, or damage the lines already drawn. As a
result I often see failed prints with the PA pattern, or moderate
damage to already drawn lines.
This change adds a 1 layer hop between each move to eliminate
nozzle drag.
---
 src/libslic3r/calib.cpp | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/libslic3r/calib.cpp b/src/libslic3r/calib.cpp
index 7d279e1895..120764885f 100644
--- a/src/libslic3r/calib.cpp
+++ b/src/libslic3r/calib.cpp
@@ -557,6 +557,9 @@ void CalibPressureAdvancePattern::generate_custom_gcodes(const DynamicPrintConfi
 
     // draw pressure advance pattern
     for (int i = 0; i < m_num_layers; ++i) {
+        const double layer_height = height_first_layer() + (i * height_layer());
+        const double zhop_height = layer_height + height_layer();
+
         if (i > 0) {
             gcode << "; end pressure advance pattern for layer\n";
             CustomGCode::Item item;
@@ -568,7 +571,6 @@ void CalibPressureAdvancePattern::generate_custom_gcodes(const DynamicPrintConfi
             gcode = std::stringstream(); // reset for next layer contents
             gcode << "; start pressure advance pattern for layer\n";
 
-            const double layer_height = height_first_layer() + (i * height_layer());
             gcode << m_writer.travel_to_z(layer_height, "Move to layer height");
         }
 
@@ -606,7 +608,9 @@ void CalibPressureAdvancePattern::generate_custom_gcodes(const DynamicPrintConfi
         double initial_x = to_x;
         double initial_y = to_y;
 
+        gcode << m_writer.travel_to_z(zhop_height, "z-hop before move");
         gcode << move_to(Vec2d(to_x, to_y), m_writer, "Move to pattern start");
+        gcode << m_writer.travel_to_z(layer_height, "undo z-hop");
 
         for (int j = 0; j < num_patterns; ++j) {
             // increment pressure advance
@@ -631,15 +635,21 @@ void CalibPressureAdvancePattern::generate_custom_gcodes(const DynamicPrintConfi
                 if (k != wall_count() - 1) {
                     // perimeters not done yet. move to next perimeter
                     to_x += line_spacing_angle();
+                    gcode << m_writer.travel_to_z(zhop_height, "z-hop before move");
                     gcode << move_to(Vec2d(to_x, to_y), m_writer, "Move to start next pattern wall");
+                    gcode << m_writer.travel_to_z(layer_height, "undo z-hop");
                 } else if (j != num_patterns - 1) {
                     // patterns not done yet. move to next pattern
                     to_x += m_pattern_spacing + line_width();
+                    gcode << m_writer.travel_to_z(zhop_height, "z-hop before move");
                     gcode << move_to(Vec2d(to_x, to_y), m_writer, "Move to next pattern");
+                    gcode << m_writer.travel_to_z(layer_height, "undo z-hop");
                 } else if (i != m_num_layers - 1) {
                     // layers not done yet. move back to start
                     to_x = initial_x;
+                    gcode << m_writer.travel_to_z(zhop_height, "z-hop before move");
                     gcode << move_to(Vec2d(to_x, to_y), m_writer, "Move back to start position");
+                    gcode << m_writer.travel_to_z(layer_height, "undo z-hop");
                 } else {
                     // everything done
                 }