From bdbeb34158a28cc0d042bdee587c7751ee966019 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Luk=C3=A1=C5=A1=20Hejl?= <hejl.lukas@gmail.com>
Date: Fri, 16 Aug 2024 08:35:49 -0400
Subject: [PATCH] Accumulate the total estimated print in doubles instead of
 floats.

Because total print time is typically a big floating point number and the time of trapezoid is typically a small number, summing those numbers leads to a loss in precision. Switching to doubles reduces the loss of precision.

(cherry picked from commit c5982f40196c178bd824c556ac11e8c6f67d5e7a)
---
 src/libslic3r/GCode/GCodeProcessor.cpp | 10 +++++-----
 src/libslic3r/GCode/GCodeProcessor.hpp |  6 ++++--
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/libslic3r/GCode/GCodeProcessor.cpp b/src/libslic3r/GCode/GCodeProcessor.cpp
index 67d7e8c3a4..6302325f0d 100644
--- a/src/libslic3r/GCode/GCodeProcessor.cpp
+++ b/src/libslic3r/GCode/GCodeProcessor.cpp
@@ -417,7 +417,7 @@ void GCodeProcessor::TimeMachine::calculate_time(GCodeProcessorResult& result, P
         if (i == 0)
             block_time += additional_time;
 
-        time += block_time;
+        time += double(block_time);
         result.moves[block.move_id].time[static_cast<size_t>(mode)] = block_time;
         gcode_time.cache += block_time;
         //BBS
@@ -514,12 +514,12 @@ void GCodeProcessor::TimeMachine::calculate_time(GCodeProcessorResult& result, P
                 std::nullopt
             });
         }
-        g1_times_cache.push_back({ block.g1_line_id, block.remaining_internal_g1_lines, time });
+        g1_times_cache.push_back({ block.g1_line_id, block.remaining_internal_g1_lines, float(time) });
         // update times for remaining time to printer stop placeholders
         auto it_stop_time = std::lower_bound(stop_times.begin(), stop_times.end(), block.g1_line_id,
             [](const StopTime& t, unsigned int value) { return t.g1_line_id < value; });
         if (it_stop_time != stop_times.end() && it_stop_time->g1_line_id == block.g1_line_id)
-            it_stop_time->elapsed_time = time;
+            it_stop_time->elapsed_time = float(time);
     }
 
     if (keep_last_n_blocks) {
@@ -2561,7 +2561,7 @@ void GCodeProcessor::finalize(bool post_process)
 
 float GCodeProcessor::get_time(PrintEstimatedStatistics::ETimeMode mode) const
 {
-    return (mode < PrintEstimatedStatistics::ETimeMode::Count) ? m_time_processor.machines[static_cast<size_t>(mode)].time : 0.0f;
+    return (mode < PrintEstimatedStatistics::ETimeMode::Count) ? float(m_time_processor.machines[static_cast<size_t>(mode)].time) : 0.0f;
 }
 
 float GCodeProcessor::get_prepare_time(PrintEstimatedStatistics::ETimeMode mode) const
@@ -2571,7 +2571,7 @@ float GCodeProcessor::get_prepare_time(PrintEstimatedStatistics::ETimeMode mode)
 
 std::string GCodeProcessor::get_time_dhm(PrintEstimatedStatistics::ETimeMode mode) const
 {
-    return (mode < PrintEstimatedStatistics::ETimeMode::Count) ? short_time(get_time_dhms(m_time_processor.machines[static_cast<size_t>(mode)].time)) : std::string("N/A");
+    return (mode < PrintEstimatedStatistics::ETimeMode::Count) ? short_time(get_time_dhms(float(m_time_processor.machines[static_cast<size_t>(mode)].time))) : std::string("N/A");
 }
 
 std::vector<std::pair<CustomGCode::Type, std::pair<float, float>>> GCodeProcessor::get_custom_gcode_times(PrintEstimatedStatistics::ETimeMode mode, bool include_remaining) const
diff --git a/src/libslic3r/GCode/GCodeProcessor.hpp b/src/libslic3r/GCode/GCodeProcessor.hpp
index f280bc97cb..f55d414514 100644
--- a/src/libslic3r/GCode/GCodeProcessor.hpp
+++ b/src/libslic3r/GCode/GCodeProcessor.hpp
@@ -459,7 +459,7 @@ class Print;
                 AxisCoords axis_feedrate; // mm/s
                 AxisCoords abs_axis_feedrate; // mm/s
 
-                //BBS: unit vector of enter speed and exit speed in x-y-z space. 
+                //BBS: unit vector of enter speed and exit speed in x-y-z space.
                 //For line move, there are same. For arc move, there are different.
                 Vec3f enter_direction;
                 Vec3f exit_direction;
@@ -508,7 +508,9 @@ class Print;
             // hard limit for the travel acceleration, to which the firmware will clamp.
             float max_travel_acceleration; // mm/s^2
             float extrude_factor_override_percentage;
-            float time; // s
+            // We accumulate total print time in doubles to reduce the loss of precision
+            // while adding big floating numbers with small float numbers.
+            double time; // s
             struct StopTime
             {
                 unsigned int g1_line_id;