Implemented an initial priming line for a single-material print

on a Prusa Multi-Material printer.

xs/src/libslic3r/GCode.cpp

@@ -219,6 +219,19 @@ std::string WipeTowerIntegration::prime(GCode &gcodegen)
     return gcode;
 }
 
+std::string WipeTowerIntegration::prime_single_color_print(const Print & /* print */, unsigned int initial_tool, GCode & /* gcodegen */)
+{
+    std::string gcode = "\
+G1 Z0.250 F7200.000\n\
+G1 X50.0 E80.0  F1000.0\n\
+G1 X160.0 E20.0  F1000.0\n\
+G1 Z0.200 F7200.000\n\
+G1 X220.0 E13 F1000.0\n\
+G1 X240.0 E0 F1000.0\n\
+G1 E-4 F1000.0\n";
+    return gcode;
+}
+
 std::string WipeTowerIntegration::tool_change(GCode &gcodegen, int extruder_id, bool finish_layer)
 {
     std::string gcode;
@@ -673,10 +686,12 @@ bool GCode::_do_export(Print &print, FILE *file)
         // All extrusion moves with the same top layer height are extruded uninterrupted.
         std::vector<std::pair<coordf_t, std::vector<LayerToPrint>>> layers_to_print = collect_layers_to_print(print);
         // Prusa Multi-Material wipe tower.
-        if (print.has_wipe_tower() && 
+        if (print.has_wipe_tower()) {
-            ! tool_ordering.empty() && tool_ordering.front().wipe_tower_partitions > 0) {
+            if (tool_ordering.has_wipe_tower()) {
                 m_wipe_tower.reset(new WipeTowerIntegration(print.config, *print.m_wipe_tower_priming.get(), print.m_wipe_tower_tool_changes, *print.m_wipe_tower_final_purge.get()));
 			    write(file, m_wipe_tower->prime(*this));
+            } else
+                write(file, WipeTowerIntegration::prime_single_color_print(print, initial_extruder_id, *this));
         }
         // Extrude the layers.
         for (auto &layer : layers_to_print) {

xs/src/libslic3r/GCode.hpp

@@ -90,6 +90,7 @@ public:
         m_brim_done(false) {}
 
     std::string prime(GCode &gcodegen);
+    static std::string WipeTowerIntegration::prime_single_color_print(const Print & /* print */, unsigned int initial_tool, GCode & /* gcodegen */);
     void next_layer() { ++ m_layer_idx; m_tool_change_idx = 0; }
     std::string tool_change(GCode &gcodegen, int extruder_id, bool finish_layer);
     std::string finalize(GCode &gcodegen);

xs/src/libslic3r/GCode/ToolOrdering.cpp

@@ -121,7 +121,7 @@ void ToolOrdering::collect_extruders(const PrintObject &object)
         LayerTools &layer_tools = this->tools_for_layer(layer->print_z);
         // What extruders are required to print this object layer?
         for (size_t region_id = 0; region_id < object.print()->regions.size(); ++ region_id) {
-            const LayerRegion *layerm = layer->regions[region_id];
+			const LayerRegion *layerm = (region_id < layer->regions.size()) ? layer->regions[region_id] : nullptr;
             if (layerm == nullptr)
                 continue;
             const PrintRegion &region = *object.print()->regions[region_id];

xs/src/libslic3r/GCode/ToolOrdering.hpp

@@ -71,6 +71,7 @@ public:
 	const LayerTools&   back()        const { return m_layer_tools.back(); }
 	bool 				empty()       const { return m_layer_tools.empty(); }
 	const std::vector<LayerTools>& layer_tools() const { return m_layer_tools; }
+	bool 				has_wipe_tower() const { return ! m_layer_tools.empty() && m_first_printing_extruder != (size_t)-1 && m_layer_tools.front().wipe_tower_partitions > 0; }
 
 private:
 	void				initialize_layers(std::vector<coordf_t> &zs);

xs/src/libslic3r/GCode/WipeTowerPrusaMM.cpp

@@ -388,7 +388,11 @@ WipeTower::ToolChangeResult WipeTowerPrusaMM::prime(float first_layer_height, st
 	this->m_num_layer_changes 	= 0;
 	this->m_current_tool 		= tools.front();
 
-	box_coordinates cleaning_box(xy(0.f, - 4.0f), m_wipe_tower_width, wipe_area);
+    // The Prusa i3 MK2 has a working space of [0, -2.2] to [250, 210].
+    // Due to the XYZ calibration, this working space may shrink slightly from all directions,
+    // therefore the homing position is shifted inside the bed by 0.2 in the firmware to [0.2, -2.0].
+//	box_coordinates cleaning_box(xy(0.5f, - 1.5f), m_wipe_tower_width, wipe_area);
+	box_coordinates cleaning_box(xy(5.f, 0.f), m_wipe_tower_width, wipe_area);
 
 	PrusaMultiMaterial::Writer writer;
 	writer.set_extrusion_flow(m_extrusion_flow)
@@ -401,9 +405,10 @@ WipeTower::ToolChangeResult WipeTowerPrusaMM::prime(float first_layer_height, st
 		  .speed_override(100);
 
 	// Always move to the starting position.
-	writer.travel(cleaning_box.ld, 7200);
+	writer.set_initial_position(xy(0.f, 0.f))
+		  .travel(cleaning_box.ld, 7200)
 	// Increase the extruder driver current to allow fast ramming.
-	writer.set_extruder_trimpot(750);
+		  .set_extruder_trimpot(750);
 
 	if (purpose == PURPOSE_EXTRUDE || purpose == PURPOSE_MOVE_TO_TOWER_AND_EXTRUDE) {
 		for (size_t idx_tool = 0; idx_tool < tools.size(); ++ idx_tool) {

xs/src/libslic3r/Print.cpp

@@ -971,7 +971,7 @@ void Print::_make_wipe_tower()
     // Let the ToolOrdering class know there will be initial priming extrusions at the start of the print.
     m_tool_ordering = ToolOrdering(*this, (unsigned int)-1, true);
     unsigned int initial_extruder_id = m_tool_ordering.first_extruder();
-    if (initial_extruder_id == (unsigned int)-1 || m_tool_ordering.front().wipe_tower_partitions == 0)
+    if (! m_tool_ordering.has_wipe_tower())
         // Don't generate any wipe tower.
         return;
 

xs/src/slic3r/GUI/3DScene.cpp

@@ -950,6 +950,9 @@ void _3DScene::_load_wipe_tower_toolpaths(
     const std::vector<std::string> &tool_colors_str,
     bool                            use_VBOs)
 {
+    if (print->m_wipe_tower_tool_changes.empty())
+        return;
+
     std::vector<float> tool_colors = parse_colors(tool_colors_str);
 
     struct Ctxt
@@ -978,7 +981,9 @@ void _3DScene::_load_wipe_tower_toolpaths(
 
     ctxt.print          = print;
     ctxt.tool_colors    = tool_colors.empty() ? nullptr : &tool_colors;
+	if (print->m_wipe_tower_priming)
 		ctxt.priming.emplace_back(*print->m_wipe_tower_priming.get());
+	if (print->m_wipe_tower_final_purge)
 		ctxt.final.emplace_back(*print->m_wipe_tower_final_purge.get());
     
     BOOST_LOG_TRIVIAL(debug) << "Loading wipe tower toolpaths in parallel - start";