From bf6a1816b44ecba09e17675ba928922a6fe42f01 Mon Sep 17 00:00:00 2001
From: Scott Lahteine <github@thinkyhead.com>
Date: Sat, 18 Nov 2017 06:27:00 -0600
Subject: [PATCH] Display volumetric ratio in terms of E mm

---
 Marlin/Marlin_main.cpp         | 1 +
 Marlin/planner.cpp             | 1 +
 Marlin/planner.h               | 1 +
 Marlin/temperature.cpp         | 5 +++--
 Marlin/ultralcd_impl_DOGM.h    | 5 +----
 Marlin/ultralcd_impl_HD44780.h | 2 +-
 6 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/Marlin/Marlin_main.cpp b/Marlin/Marlin_main.cpp
index 2951dc716..f340844dd 100644
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@@ -9689,6 +9689,7 @@ inline void gcode_M400() { stepper.synchronize(); }
   inline void gcode_M404() {
     if (parser.seen('W')) {
       filament_width_nominal = parser.value_linear_units();
+      planner.volumetric_area_nominal = CIRCLE_AREA(filament_width_nominal * 0.5);
     }
     else {
       SERIAL_PROTOCOLPGM("Filament dia (nominal mm):");
diff --git a/Marlin/planner.cpp b/Marlin/planner.cpp
index e50770861..daaafa90c 100644
--- a/Marlin/planner.cpp
+++ b/Marlin/planner.cpp
@@ -95,6 +95,7 @@ int16_t Planner::flow_percentage[EXTRUDERS] = ARRAY_BY_EXTRUDERS1(100); // Extru
 
 float Planner::e_factor[EXTRUDERS],               // The flow percentage and volumetric multiplier combine to scale E movement
       Planner::filament_size[EXTRUDERS],          // diameter of filament (in millimeters), typically around 1.75 or 2.85, 0 disables the volumetric calculations for the extruder
+      Planner::volumetric_area_nominal = CIRCLE_AREA((DEFAULT_NOMINAL_FILAMENT_DIA) * 0.5), // Nominal cross-sectional area
       Planner::volumetric_multiplier[EXTRUDERS];  // Reciprocal of cross-sectional area of filament (in mm^2). Pre-calculated to reduce computation in the planner
 
 uint32_t Planner::max_acceleration_steps_per_s2[XYZE_N],
diff --git a/Marlin/planner.h b/Marlin/planner.h
index 17421b5bc..fb593f618 100644
--- a/Marlin/planner.h
+++ b/Marlin/planner.h
@@ -144,6 +144,7 @@ class Planner {
 
     static float e_factor[EXTRUDERS],               // The flow percentage and volumetric multiplier combine to scale E movement
                  filament_size[EXTRUDERS],          // diameter of filament (in millimeters), typically around 1.75 or 2.85, 0 disables the volumetric calculations for the extruder
+                 volumetric_area_nominal,           // Nominal cross-sectional area
                  volumetric_multiplier[EXTRUDERS];  // Reciprocal of cross-sectional area of filament (in mm^2). Pre-calculated to reduce computation in the planner
                                                     // May be auto-adjusted by a filament width sensor
 
diff --git a/Marlin/temperature.cpp b/Marlin/temperature.cpp
index 1ab024d86..d6e8d80e1 100644
--- a/Marlin/temperature.cpp
+++ b/Marlin/temperature.cpp
@@ -814,8 +814,9 @@ void Temperature::manage_heater() {
 
       // Get the delayed info and add 100 to reconstitute to a percent of
       // the nominal filament diameter then square it to get an area
-      const float vmroot = measurement_delay[meas_shift_index] * 0.01 + 1.0;
-      planner.volumetric_multiplier[FILAMENT_SENSOR_EXTRUDER_NUM] = vmroot <= 0.1 ? 0.01 : sq(vmroot);
+      float vmroot = measurement_delay[meas_shift_index] * 0.01 + 1.0;
+      NOLESS(vmroot, 0.1);
+      planner.volumetric_multiplier[FILAMENT_SENSOR_EXTRUDER_NUM] = 1.0 / CIRCLE_AREA(vmroot / 2);
       planner.refresh_e_factor(FILAMENT_SENSOR_EXTRUDER_NUM);
     }
   #endif // FILAMENT_WIDTH_SENSOR
diff --git a/Marlin/ultralcd_impl_DOGM.h b/Marlin/ultralcd_impl_DOGM.h
index d05fe9c68..57cf12dee 100644
--- a/Marlin/ultralcd_impl_DOGM.h
+++ b/Marlin/ultralcd_impl_DOGM.h
@@ -651,12 +651,9 @@ static void lcd_implementation_status_screen() {
     #if ENABLED(FILAMENT_LCD_DISPLAY)
       strcpy(wstring, ftostr12ns(filament_width_meas));
       if (parser.volumetric_enabled)
-        strcpy(mstring, itostr3(100.0 * filament_width_meas / filament_width_nominal));
+        strcpy(mstring, itostr3(100.0 * planner.volumetric_area_nominal / planner.volumetric_multiplier[FILAMENT_SENSOR_EXTRUDER_NUM]));
       else
         strcpy_P(mstring, PSTR("---"));
-      // Alternatively, show the ratio between cross-sectional areas:
-      //strcpy(mstring, itostr3(100.0 / CIRCLE_AREA(filament_width_nominal * 0.5)
-      //                              / planner.volumetric_multiplier[FILAMENT_SENSOR_EXTRUDER_NUM]));
     #endif
   }
 
diff --git a/Marlin/ultralcd_impl_HD44780.h b/Marlin/ultralcd_impl_HD44780.h
index a4c6b18fb..760443edf 100644
--- a/Marlin/ultralcd_impl_HD44780.h
+++ b/Marlin/ultralcd_impl_HD44780.h
@@ -858,7 +858,7 @@ static void lcd_implementation_status_screen() {
       lcd.print(ftostr12ns(filament_width_meas));
       lcd_printPGM(PSTR(" V"));
       if (parser.volumetric_enabled) {
-        lcd.print(itostr3(100.0 * filament_width_meas / filament_width_nominal));
+        lcd.print(itostr3(100.0 * planner.volumetric_area_nominal / planner.volumetric_multiplier[FILAMENT_SENSOR_EXTRUDER_NUM]));
         lcd.write('%');
       }
       else