SPE-1739: Fixed calculation of gcode preview sequential slider endpoints

src/libslic3r/GCode.cpp

@@ -901,6 +901,7 @@ namespace DoExport {
         silent_time_estimator_enabled = (config.gcode_flavor == gcfMarlinLegacy || config.gcode_flavor == gcfMarlinFirmware)
                                         && config.silent_mode;
         processor.reset();
+        processor.initialize_result_moves();
         processor.apply_config(config);
         processor.enable_stealth_time_estimator(silent_time_estimator_enabled);
     }

src/libslic3r/GCode/GCodeProcessor.cpp

@@ -1071,8 +1071,7 @@ void GCodeProcessor::process_file(const std::string& filename, std::function<voi
     // process gcode
     m_result.filename = filename;
     m_result.id = ++s_result_id;
-    // 1st move must be a dummy move
+    initialize_result_moves();
-    m_result.moves.emplace_back(GCodeProcessorResult::MoveVertex());
     size_t parse_line_callback_cntr = 10000;
     m_parser.parse_file(filename, [this, cancel_callback, &parse_line_callback_cntr](GCodeReader& reader, const GCodeReader::GCodeLine& line) {
         if (-- parse_line_callback_cntr == 0) {
@@ -1099,8 +1098,6 @@ void GCodeProcessor::initialize(const std::string& filename)
     // process gcode
     m_result.filename = filename;
     m_result.id = ++s_result_id;
-    // 1st move must be a dummy move
-    m_result.moves.emplace_back(GCodeProcessorResult::MoveVertex());
 }
 
 void GCodeProcessor::process_buffer(const std::string &buffer)

src/libslic3r/GCode/GCodeProcessor.hpp

@@ -639,6 +639,11 @@ namespace Slic3r {
 
         // Streaming interface, for processing G-codes just generated by PrusaSlicer in a pipelined fashion.
         void initialize(const std::string& filename);
+        void initialize_result_moves() {
+            // 1st move must be a dummy move
+            assert(m_result.moves.empty());
+            m_result.moves.emplace_back(GCodeProcessorResult::MoveVertex());
+        }
         void process_buffer(const std::string& buffer);
         void finalize(bool post_process);
 

src/slic3r/GUI/GCodeViewer.cpp

@@ -2150,6 +2150,7 @@ void GCodeViewer::load_toolpaths(const GCodeProcessorResult& gcode_result)
 
     // layers zs / roles / extruder ids -> extract from result
     size_t last_travel_s_id = 0;
+    size_t first_travel_s_id = 0;
     seams_count = 0;
     for (size_t i = 0; i < m_moves_count; ++i) {
         const GCodeProcessorResult::MoveVertex& move = gcode_result.moves[i];
@@ -2163,8 +2164,10 @@ void GCodeViewer::load_toolpaths(const GCodeProcessorResult& gcode_result)
                 // layers zs
                 const double* const last_z = m_layers.empty() ? nullptr : &m_layers.get_zs().back();
                 const double z = static_cast<double>(move.position.z());
-                if (last_z == nullptr || z < *last_z - EPSILON || *last_z + EPSILON < z)
+                if (last_z == nullptr || z < *last_z - EPSILON || *last_z + EPSILON < z) {
-                    m_layers.append(z, { last_travel_s_id, move_id });
+                    const size_t start_it = (m_layers.empty() && first_travel_s_id != 0) ? first_travel_s_id : last_travel_s_id;
+                    m_layers.append(z, { start_it, move_id });
+                }
                 else
                     m_layers.get_ranges().back().last = move_id;
             }
@@ -2177,7 +2180,8 @@ void GCodeViewer::load_toolpaths(const GCodeProcessorResult& gcode_result)
         else if (move.type == EMoveType::Travel) {
             if (move_id - last_travel_s_id > 1 && !m_layers.empty())
                 m_layers.get_ranges().back().last = move_id;
-
+            else if (m_layers.empty() && first_travel_s_id == 0)
+                first_travel_s_id = move_id;
             last_travel_s_id = move_id;
         }
     }
@@ -2433,8 +2437,10 @@ void GCodeViewer::refresh_render_paths(bool keep_sequential_current_first, bool
             for (size_t i = 0; i < buffer.paths.size(); ++i) {
                 const Path& path = buffer.paths[i];
                 if (path.type == EMoveType::Travel) {
-                    if (!is_travel_in_layers_range(i, m_layers_z_range[0], m_layers_z_range[1]))
+                    if (path.sub_paths.front().first.s_id > m_layers_z_range[0]) {
-                        continue;
+                        if (!is_travel_in_layers_range(i, m_layers_z_range[0], m_layers_z_range[1]))
+                            continue;
+                    }
                 }
                 else if (!is_in_layers_range(path, m_layers_z_range[0], m_layers_z_range[1]))
                     continue;