SPE-2111: Rewrite the spiral vase with interpolation between layers.

- Adds transition out to prevent a sharp edge at the top of the spiral vase.
- Interpolation in the X and Y axes is used whether vase mode is enabled.
- Maximum smoothing is automatically calculated from the nozzle diameter.

This commit comes from https://github.com/prusa3d/PrusaSlicer/pull/12142 with some refactoring.

Co-authored-by: Andrew Boktor <aboktor@microsoft.com>
Co-authored-by: SoftFever <softfeverever@gmail.com>
Co-authored-by: Vovodroid <vovodroid@users.noreply.github.com>
Co-authored-by: Tom Glastonbury <t@tg73.net>
Co-authored-by: Lukáš Hejl <hejl.lukas@gmail.com>

src/libslic3r/GCode.cpp

@@ -1509,11 +1509,12 @@ void GCodeGenerator::process_layers(
         });
     // The pipeline is variable: The vase mode filter is optional.
     const auto spiral_vase = tbb::make_filter<LayerResult, LayerResult>(slic3r_tbb_filtermode::serial_in_order,
-        [spiral_vase = this->m_spiral_vase.get()](LayerResult in) -> LayerResult {
+        [spiral_vase = this->m_spiral_vase.get(), &layers_to_print](LayerResult in) -> LayerResult {
             if (in.nop_layer_result)
                 return in;
             spiral_vase->enable(in.spiral_vase_enable);
-            return { spiral_vase->process_layer(std::move(in.gcode)), in.layer_id, in.spiral_vase_enable, in.cooling_buffer_flush};
+            bool last_layer = in.layer_id == layers_to_print.size() - 1;
+            return { spiral_vase->process_layer(std::move(in.gcode), last_layer), in.layer_id, in.spiral_vase_enable, in.cooling_buffer_flush};
         });
     const auto pressure_equalizer = tbb::make_filter<LayerResult, LayerResult>(slic3r_tbb_filtermode::serial_in_order,
         [pressure_equalizer = this->m_pressure_equalizer.get()](LayerResult in) -> LayerResult {
@@ -1602,11 +1603,12 @@ void GCodeGenerator::process_layers(
         });
     // The pipeline is variable: The vase mode filter is optional.
     const auto spiral_vase = tbb::make_filter<LayerResult, LayerResult>(slic3r_tbb_filtermode::serial_in_order,
-        [spiral_vase = this->m_spiral_vase.get()](LayerResult in)->LayerResult {
+        [spiral_vase = this->m_spiral_vase.get(), &layers_to_print](LayerResult in)->LayerResult {
             if (in.nop_layer_result)
                 return in;
             spiral_vase->enable(in.spiral_vase_enable);
-            return { spiral_vase->process_layer(std::move(in.gcode)), in.layer_id, in.spiral_vase_enable, in.cooling_buffer_flush };
+            bool last_layer = in.layer_id == layers_to_print.size() - 1;
+            return { spiral_vase->process_layer(std::move(in.gcode), last_layer), in.layer_id, in.spiral_vase_enable, in.cooling_buffer_flush };
         });
     const auto pressure_equalizer = tbb::make_filter<LayerResult, LayerResult>(slic3r_tbb_filtermode::serial_in_order,
         [pressure_equalizer = this->m_pressure_equalizer.get()](LayerResult in) -> LayerResult {

src/libslic3r/GCode/SpiralVase.cpp

@@ -9,10 +9,21 @@
 #include "SpiralVase.hpp"
 #include "GCode.hpp"
 #include <sstream>
+#include <cmath>
+#include <limits>
 
 namespace Slic3r {
 
-std::string SpiralVase::process_layer(const std::string &gcode)
+static AABBTreeLines::LinesDistancer<Linef> get_layer_distancer(const std::vector<Vec2f> &layer_points)
+{
+    Linesf lines;
+    for (size_t idx = 1; idx < layer_points.size(); ++idx)
+        lines.emplace_back(layer_points[idx - 1].cast<double>(), layer_points[idx].cast<double>());
+
+    return AABBTreeLines::LinesDistancer{std::move(lines)};
+}
+
+std::string SpiralVase::process_layer(const std::string &gcode, bool last_layer)
 {
     /*  This post-processor relies on several assumptions:
         - all layers are processed through it, including those that are not supposed
@@ -24,14 +35,14 @@ std::string SpiralVase::process_layer(const std::string &gcode)
 
     // If we're not going to modify G-code, just feed it to the reader
     // in order to update positions.
-    if (! m_enabled) {
+    if (!m_enabled) {
         m_reader.parse_buffer(gcode);
         return gcode;
     }
 
     // Get total XY length for this layer by summing all extrusion moves.
-    float total_layer_length = 0;
+    float total_layer_length = 0.f;
-    float layer_height = 0;
+    float layer_height       = 0.f;
     float z                  = 0.f;
 
     {
@@ -54,18 +65,24 @@ std::string SpiralVase::process_layer(const std::string &gcode)
         });
     }
 
-    // Remove layer height from initial Z.
+    // Remove layer height from initial Z.
     z -= layer_height;
 
-    std::string new_gcode;
+    // FIXME Tapering of the transition layer only works reliably with relative extruder distances.
-    //FIXME Tapering of the transition layer only works reliably with relative extruder distances.
     // For absolute extruder distances it will be switched off.
     // Tapering the absolute extruder distances requires to process every extrusion value after the first transition
     // layer.
-    bool  transition = m_transition_layer && m_config.use_relative_e_distances.value;
+    const bool transition_in  = m_transition_layer && m_config.use_relative_e_distances.value;
-    float layer_height_factor = layer_height / total_layer_length;
+    const bool transition_out = last_layer && m_config.use_relative_e_distances.value;
+
+    const AABBTreeLines::LinesDistancer previous_layer_distancer = get_layer_distancer(m_previous_layer);
+    Vec2f                               last_point               = m_previous_layer.empty() ? Vec2f::Zero() : m_previous_layer.back();
     float                               len                      = 0.f;
-    m_reader.parse_buffer(gcode, [&new_gcode, &z, total_layer_length, layer_height_factor, transition, &len]
+
+    std::string        new_gcode, transition_gcode;
+    std::vector<Vec2f> current_layer;
+    m_reader.parse_buffer(gcode, [z, total_layer_length, layer_height, transition_in, transition_out, smooth_spiral = m_smooth_spiral, max_xy_smoothing = m_max_xy_smoothing,
+                                  &len, &last_point, &new_gcode, &transition_gcode, &current_layer, &previous_layer_distancer]
         (GCodeReader &reader, GCodeReader::GCodeLine line) {
         if (line.cmd_is("G1")) {
             if (line.has_z()) {
@@ -74,32 +91,63 @@ std::string SpiralVase::process_layer(const std::string &gcode)
                 line.set(reader, Z, z);
                 new_gcode += line.raw() + '\n';
                 return;
-            } else {
+            } else if (line.has_x() || line.has_y()) { // Sometimes lines have X/Y but the move is to the last position.
-                float dist_XY = line.dist_XY(reader);
+                if (const float dist_XY = line.dist_XY(reader); dist_XY > 0 && line.extruding(reader)) { // Exclude wipe and retract
-                if (dist_XY > 0) {
-                    // horizontal move
-                    if (line.extruding(reader)) {
                     len += dist_XY;
-                        line.set(reader, Z, z + len * layer_height_factor);
+                    const float factor = len / total_layer_length;
-                        if (transition && line.has(E))
+                    if (transition_in)
-                            // Transition layer, modulate the amount of extrusion from zero to the final value.
+                        // Transition layer, interpolate the amount of extrusion from zero to the final value.
-                            line.set(reader, E, line.value(E) * len / total_layer_length);
+                        line.set(reader, E, line.e() * factor, 5);
+                    else if (transition_out) {
+                        // We want the last layer to ramp down extrusion, but without changing z height!
+                        // So clone the line before we mess with its Z and duplicate it into a new layer that ramps down E
+                        // We add this new layer at the very end
+                        GCodeReader::GCodeLine transition_line(line);
+                        transition_line.set(reader, E, line.e() * (1.f - factor), 5);
+                        transition_gcode += transition_line.raw() + '\n';
+                    }
+                    // This line is the core of Spiral Vase mode, ramp up the Z smoothly
+                    line.set(reader, Z, z + factor * layer_height);
+                    if (smooth_spiral) {
+                        // Now we also need to try to interpolate X and Y
+                        Vec2f p(line.x(), line.y());   // Get current x/y coordinates
+                        current_layer.emplace_back(p); // Store that point for later use on the next layer
+
+                        auto [nearest_distance, idx, nearest_pt] = previous_layer_distancer.distance_from_lines_extra<false>(p.cast<double>());
+                        if (nearest_distance < max_xy_smoothing) {
+                            // Interpolate between the point on this layer and the point on the previous layer
+                            Vec2f target = nearest_pt.cast<float>() * (1.f - factor) + p * factor;
+                            line.set(reader, X, target.x());
+                            line.set(reader, Y, target.y());
+                            // We need to figure out the distance of this new line!
+                            float modified_dist_XY = (last_point - target).norm();
+                            // Scale the extrusion amount according to change in length
+                            line.set(reader, E, line.e() * modified_dist_XY / dist_XY, 5);
+                            last_point = target;
+                        } else {
+                            last_point = p;
+                        }
+                    }
                     new_gcode += line.raw() + '\n';
                 }
                 return;
-                
                 /*  Skip travel moves: the move to first perimeter point will
                     cause a visible seam when loops are not aligned in XY; by skipping
                     it we blend the first loop move in the XY plane (although the smoothness
                     of such blend depend on how long the first segment is; maybe we should
-                        enforce some minimum length?).  */
+                    enforce some minimum length?).
-                }
+                    When smooth_spiral is enabled, we're gonna end up exactly where the next layer should
+                    start anyway, so we don't need the travel move */
             }
         }
+
         new_gcode += line.raw() + '\n';
+        if (transition_out)
+            transition_gcode += line.raw() + '\n';
     });
 
-    return new_gcode;
+    m_previous_layer = std::move(current_layer);
+    return new_gcode + transition_gcode;
 }
 
 }

src/libslic3r/GCode/SpiralVase.hpp

@@ -14,31 +14,40 @@
 
 namespace Slic3r {
 
-
+class SpiralVase
-class SpiralVase {
+{
 public:
-    SpiralVase(const PrintConfig &config) : m_config(config)
+    SpiralVase() = delete;
+
+    explicit SpiralVase(const PrintConfig &config) : m_config(config)
     {
-        m_reader.z() = (float)m_config.z_offset;
+        m_reader.z() = (float) m_config.z_offset;
         m_reader.apply_config(m_config);
+
+        const double max_nozzle_diameter = *std::max_element(config.nozzle_diameter.values.begin(), config.nozzle_diameter.values.end());
+        m_max_xy_smoothing               = float(2. * max_nozzle_diameter);
     };
 
-    void 		enable(bool en) {
+    void enable(bool enable)
-   		m_transition_layer = en && ! m_enabled;
+    {
-    	m_enabled 		   = en;
+        m_transition_layer = enable && !m_enabled;
+        m_enabled          = enable;
     }
 
-    std::string process_layer(const std::string &gcode);
+    std::string process_layer(const std::string &gcode, bool last_layer);
 
 private:
     const PrintConfig  &m_config;
     GCodeReader 		m_reader;
+    float               m_max_xy_smoothing = 0.f;
 
     bool 				m_enabled = false;
     // First spiral vase layer. Layer height has to be ramped up from zero to the target layer height.
     bool 				m_transition_layer = false;
+    // Whether to interpolate XY coordinates with the previous layer. Results in no seam at layer changes
+    bool                m_smooth_spiral = true;
+    std::vector<Vec2f>  m_previous_layer;
 };
-
 }
 
 #endif // slic3r_SpiralVase_hpp_