From 1617798287945f8536b4eedeff0cddff543a9566 Mon Sep 17 00:00:00 2001
From: Scott Lahteine <github@thinkyhead.com>
Date: Sun, 25 Feb 2018 20:37:40 -0600
Subject: [PATCH] Remove conditional wrap from ubl.h

---
 Marlin/ubl.h | 609 +++++++++++++++++++++++++--------------------------
 1 file changed, 303 insertions(+), 306 deletions(-)

diff --git a/Marlin/ubl.h b/Marlin/ubl.h
index 70fde0fff1..360ff7694a 100644
--- a/Marlin/ubl.h
+++ b/Marlin/ubl.h
@@ -25,353 +25,350 @@
 
 #include "MarlinConfig.h"
 
-#if ENABLED(AUTO_BED_LEVELING_UBL)
+//#define UBL_DEVEL_DEBUGGING
 
-  //#define UBL_DEVEL_DEBUGGING
+#include "Marlin.h"
+#include "planner.h"
+#include "math.h"
+#include "vector_3.h"
+#include "configuration_store.h"
 
-  #include "Marlin.h"
-  #include "planner.h"
-  #include "math.h"
-  #include "vector_3.h"
-  #include "configuration_store.h"
+#define UBL_VERSION "1.01"
+#define UBL_OK false
+#define UBL_ERR true
 
-  #define UBL_VERSION "1.01"
-  #define UBL_OK false
-  #define UBL_ERR true
+#define USE_NOZZLE_AS_REFERENCE 0
+#define USE_PROBE_AS_REFERENCE 1
 
-  #define USE_NOZZLE_AS_REFERENCE 0
-  #define USE_PROBE_AS_REFERENCE 1
+// ubl_motion.cpp
 
-  // ubl_motion.cpp
+#if ENABLED(UBL_DEVEL_DEBUGGING)
+  void debug_current_and_destination(const char * const title);
+#else
+  FORCE_INLINE void debug_current_and_destination(const char * const title) { UNUSED(title); }
+#endif
 
-  #if ENABLED(UBL_DEVEL_DEBUGGING)
-    void debug_current_and_destination(const char * const title);
-  #else
-    FORCE_INLINE void debug_current_and_destination(const char * const title) { UNUSED(title); }
-  #endif
+// ubl_G29.cpp
 
-  // ubl_G29.cpp
+enum MeshPointType { INVALID, REAL, SET_IN_BITMAP };
 
-  enum MeshPointType { INVALID, REAL, SET_IN_BITMAP };
+// External references
 
-  // External references
+char *ftostr43sign(const float&, char);
+void home_all_axes();
 
-  char *ftostr43sign(const float&, char);
-  void home_all_axes();
+extern uint8_t ubl_cnt;
 
-  extern uint8_t ubl_cnt;
+///////////////////////////////////////////////////////////////////////////////////////////////////////
 
-  ///////////////////////////////////////////////////////////////////////////////////////////////////////
+#if ENABLED(ULTRA_LCD)
+  extern char lcd_status_message[];
+  void lcd_quick_feedback(const bool clear_buttons);
+#endif
 
-  #if ENABLED(ULTRA_LCD)
-    extern char lcd_status_message[];
-    void lcd_quick_feedback(const bool clear_buttons);
-  #endif
+#define MESH_X_DIST (float(MESH_MAX_X - (MESH_MIN_X)) / float(GRID_MAX_POINTS_X - 1))
+#define MESH_Y_DIST (float(MESH_MAX_Y - (MESH_MIN_Y)) / float(GRID_MAX_POINTS_Y - 1))
 
-  #define MESH_X_DIST (float(MESH_MAX_X - (MESH_MIN_X)) / float(GRID_MAX_POINTS_X - 1))
-  #define MESH_Y_DIST (float(MESH_MAX_Y - (MESH_MIN_Y)) / float(GRID_MAX_POINTS_Y - 1))
+class unified_bed_leveling {
+  private:
 
-  class unified_bed_leveling {
-    private:
+    static int    g29_verbose_level,
+                  g29_phase_value,
+                  g29_repetition_cnt,
+                  g29_storage_slot,
+                  g29_map_type;
+    static bool   g29_c_flag, g29_x_flag, g29_y_flag;
+    static float  g29_x_pos, g29_y_pos,
+                  g29_card_thickness,
+                  g29_constant;
 
-      static int    g29_verbose_level,
-                    g29_phase_value,
-                    g29_repetition_cnt,
-                    g29_storage_slot,
-                    g29_map_type;
-      static bool   g29_c_flag, g29_x_flag, g29_y_flag;
-      static float  g29_x_pos, g29_y_pos,
-                    g29_card_thickness,
-                    g29_constant;
+    #if HAS_BED_PROBE
+      static int  g29_grid_size;
+    #endif
 
-      #if HAS_BED_PROBE
-        static int  g29_grid_size;
-      #endif
+    #if ENABLED(NEWPANEL)
+      static void move_z_with_encoder(const float &multiplier);
+      static float measure_point_with_encoder();
+      static float measure_business_card_thickness(float in_height);
+      static void manually_probe_remaining_mesh(const float&, const float&, const float&, const float&, const bool) _O0;
+      static void fine_tune_mesh(const float &rx, const float &ry, const bool do_ubl_mesh_map) _O0;
+    #endif
 
-      #if ENABLED(NEWPANEL)
-        static void move_z_with_encoder(const float &multiplier);
-        static float measure_point_with_encoder();
-        static float measure_business_card_thickness(float in_height);
-        static void manually_probe_remaining_mesh(const float&, const float&, const float&, const float&, const bool) _O0;
-        static void fine_tune_mesh(const float &rx, const float &ry, const bool do_ubl_mesh_map) _O0;
-      #endif
+    static bool g29_parameter_parsing() _O0;
+    static void find_mean_mesh_height();
+    static void shift_mesh_height();
+    static void probe_entire_mesh(const float &rx, const float &ry, const bool do_ubl_mesh_map, const bool stow_probe, bool do_furthest) _O0;
+    static void tilt_mesh_based_on_3pts(const float &z1, const float &z2, const float &z3);
+    static void tilt_mesh_based_on_probed_grid(const bool do_ubl_mesh_map);
+    static void g29_what_command();
+    static void g29_eeprom_dump();
+    static void g29_compare_current_mesh_to_stored_mesh();
+    static bool smart_fill_one(const uint8_t x, const uint8_t y, const int8_t xdir, const int8_t ydir);
+    static void smart_fill_mesh();
 
-      static bool g29_parameter_parsing() _O0;
-      static void find_mean_mesh_height();
-      static void shift_mesh_height();
-      static void probe_entire_mesh(const float &rx, const float &ry, const bool do_ubl_mesh_map, const bool stow_probe, bool do_furthest) _O0;
-      static void tilt_mesh_based_on_3pts(const float &z1, const float &z2, const float &z3);
-      static void tilt_mesh_based_on_probed_grid(const bool do_ubl_mesh_map);
-      static void g29_what_command();
-      static void g29_eeprom_dump();
-      static void g29_compare_current_mesh_to_stored_mesh();
-      static bool smart_fill_one(const uint8_t x, const uint8_t y, const int8_t xdir, const int8_t ydir);
-      static void smart_fill_mesh();
+  public:
 
-    public:
+    static void echo_name();
+    static void report_state();
+    static void save_ubl_active_state_and_disable();
+    static void restore_ubl_active_state_and_leave();
+    static void display_map(const int) _O0;
+    static mesh_index_pair find_closest_mesh_point_of_type(const MeshPointType, const float&, const float&, const bool, uint16_t[16]) _O0;
+    static mesh_index_pair find_furthest_invalid_mesh_point() _O0;
+    static void reset();
+    static void invalidate();
+    static void set_all_mesh_points_to_value(const float);
+    static bool sanity_check();
 
-      static void echo_name();
-      static void report_state();
-      static void save_ubl_active_state_and_disable();
-      static void restore_ubl_active_state_and_leave();
-      static void display_map(const int) _O0;
-      static mesh_index_pair find_closest_mesh_point_of_type(const MeshPointType, const float&, const float&, const bool, uint16_t[16]) _O0;
-      static mesh_index_pair find_furthest_invalid_mesh_point() _O0;
-      static void reset();
-      static void invalidate();
-      static void set_all_mesh_points_to_value(const float);
-      static bool sanity_check();
+    static void G29() _O0;                      // O0 for no optimization
+    static void smart_fill_wlsf(const float &); // O2 gives smaller code than Os on A2560
+    static int8_t storage_slot;
 
-      static void G29() _O0;                      // O0 for no optimization
-      static void smart_fill_wlsf(const float &); // O2 gives smaller code than Os on A2560
-      static int8_t storage_slot;
+    static float z_values[GRID_MAX_POINTS_X][GRID_MAX_POINTS_Y];
 
-      static float z_values[GRID_MAX_POINTS_X][GRID_MAX_POINTS_Y];
+    // 15 is the maximum nubmer of grid points supported + 1 safety margin for now,
+    // until determinism prevails
+    constexpr static float _mesh_index_to_xpos[16] PROGMEM = {
+                              MESH_MIN_X +  0 * (MESH_X_DIST), MESH_MIN_X +  1 * (MESH_X_DIST),
+                              MESH_MIN_X +  2 * (MESH_X_DIST), MESH_MIN_X +  3 * (MESH_X_DIST),
+                              MESH_MIN_X +  4 * (MESH_X_DIST), MESH_MIN_X +  5 * (MESH_X_DIST),
+                              MESH_MIN_X +  6 * (MESH_X_DIST), MESH_MIN_X +  7 * (MESH_X_DIST),
+                              MESH_MIN_X +  8 * (MESH_X_DIST), MESH_MIN_X +  9 * (MESH_X_DIST),
+                              MESH_MIN_X + 10 * (MESH_X_DIST), MESH_MIN_X + 11 * (MESH_X_DIST),
+                              MESH_MIN_X + 12 * (MESH_X_DIST), MESH_MIN_X + 13 * (MESH_X_DIST),
+                              MESH_MIN_X + 14 * (MESH_X_DIST), MESH_MIN_X + 15 * (MESH_X_DIST)
+                            };
 
-      // 15 is the maximum nubmer of grid points supported + 1 safety margin for now,
-      // until determinism prevails
-      constexpr static float _mesh_index_to_xpos[16] PROGMEM = {
-                                MESH_MIN_X +  0 * (MESH_X_DIST), MESH_MIN_X +  1 * (MESH_X_DIST),
-                                MESH_MIN_X +  2 * (MESH_X_DIST), MESH_MIN_X +  3 * (MESH_X_DIST),
-                                MESH_MIN_X +  4 * (MESH_X_DIST), MESH_MIN_X +  5 * (MESH_X_DIST),
-                                MESH_MIN_X +  6 * (MESH_X_DIST), MESH_MIN_X +  7 * (MESH_X_DIST),
-                                MESH_MIN_X +  8 * (MESH_X_DIST), MESH_MIN_X +  9 * (MESH_X_DIST),
-                                MESH_MIN_X + 10 * (MESH_X_DIST), MESH_MIN_X + 11 * (MESH_X_DIST),
-                                MESH_MIN_X + 12 * (MESH_X_DIST), MESH_MIN_X + 13 * (MESH_X_DIST),
-                                MESH_MIN_X + 14 * (MESH_X_DIST), MESH_MIN_X + 15 * (MESH_X_DIST)
-                              };
+    constexpr static float _mesh_index_to_ypos[16] PROGMEM = {
+                              MESH_MIN_Y +  0 * (MESH_Y_DIST), MESH_MIN_Y +  1 * (MESH_Y_DIST),
+                              MESH_MIN_Y +  2 * (MESH_Y_DIST), MESH_MIN_Y +  3 * (MESH_Y_DIST),
+                              MESH_MIN_Y +  4 * (MESH_Y_DIST), MESH_MIN_Y +  5 * (MESH_Y_DIST),
+                              MESH_MIN_Y +  6 * (MESH_Y_DIST), MESH_MIN_Y +  7 * (MESH_Y_DIST),
+                              MESH_MIN_Y +  8 * (MESH_Y_DIST), MESH_MIN_Y +  9 * (MESH_Y_DIST),
+                              MESH_MIN_Y + 10 * (MESH_Y_DIST), MESH_MIN_Y + 11 * (MESH_Y_DIST),
+                              MESH_MIN_Y + 12 * (MESH_Y_DIST), MESH_MIN_Y + 13 * (MESH_Y_DIST),
+                              MESH_MIN_Y + 14 * (MESH_Y_DIST), MESH_MIN_Y + 15 * (MESH_Y_DIST)
+                            };
 
-      constexpr static float _mesh_index_to_ypos[16] PROGMEM = {
-                                MESH_MIN_Y +  0 * (MESH_Y_DIST), MESH_MIN_Y +  1 * (MESH_Y_DIST),
-                                MESH_MIN_Y +  2 * (MESH_Y_DIST), MESH_MIN_Y +  3 * (MESH_Y_DIST),
-                                MESH_MIN_Y +  4 * (MESH_Y_DIST), MESH_MIN_Y +  5 * (MESH_Y_DIST),
-                                MESH_MIN_Y +  6 * (MESH_Y_DIST), MESH_MIN_Y +  7 * (MESH_Y_DIST),
-                                MESH_MIN_Y +  8 * (MESH_Y_DIST), MESH_MIN_Y +  9 * (MESH_Y_DIST),
-                                MESH_MIN_Y + 10 * (MESH_Y_DIST), MESH_MIN_Y + 11 * (MESH_Y_DIST),
-                                MESH_MIN_Y + 12 * (MESH_Y_DIST), MESH_MIN_Y + 13 * (MESH_Y_DIST),
-                                MESH_MIN_Y + 14 * (MESH_Y_DIST), MESH_MIN_Y + 15 * (MESH_Y_DIST)
-                              };
+    #if ENABLED(ULTIPANEL)
+      static bool lcd_map_control;
+    #endif
 
-      #if ENABLED(ULTIPANEL)
-        static bool lcd_map_control;
-      #endif
+    static volatile int encoder_diff; // Volatile because it's changed at interrupt time.
 
-      static volatile int encoder_diff; // Volatile because it's changed at interrupt time.
+    unified_bed_leveling();
 
-      unified_bed_leveling();
+    FORCE_INLINE static void set_z(const int8_t px, const int8_t py, const float &z) { z_values[px][py] = z; }
 
-      FORCE_INLINE static void set_z(const int8_t px, const int8_t py, const float &z) { z_values[px][py] = z; }
+    static int8_t get_cell_index_x(const float &x) {
+      const int8_t cx = (x - (MESH_MIN_X)) * (1.0 / (MESH_X_DIST));
+      return constrain(cx, 0, (GRID_MAX_POINTS_X) - 1);   // -1 is appropriate if we want all movement to the X_MAX
+    }                                                     // position. But with this defined this way, it is possible
+                                                          // to extrapolate off of this point even further out. Probably
+                                                          // that is OK because something else should be keeping that from
+                                                          // happening and should not be worried about at this level.
+    static int8_t get_cell_index_y(const float &y) {
+      const int8_t cy = (y - (MESH_MIN_Y)) * (1.0 / (MESH_Y_DIST));
+      return constrain(cy, 0, (GRID_MAX_POINTS_Y) - 1);   // -1 is appropriate if we want all movement to the Y_MAX
+    }                                                     // position. But with this defined this way, it is possible
+                                                          // to extrapolate off of this point even further out. Probably
+                                                          // that is OK because something else should be keeping that from
+                                                          // happening and should not be worried about at this level.
 
-      static int8_t get_cell_index_x(const float &x) {
-        const int8_t cx = (x - (MESH_MIN_X)) * (1.0 / (MESH_X_DIST));
-        return constrain(cx, 0, (GRID_MAX_POINTS_X) - 1);   // -1 is appropriate if we want all movement to the X_MAX
-      }                                                     // position. But with this defined this way, it is possible
-                                                            // to extrapolate off of this point even further out. Probably
-                                                            // that is OK because something else should be keeping that from
-                                                            // happening and should not be worried about at this level.
-      static int8_t get_cell_index_y(const float &y) {
-        const int8_t cy = (y - (MESH_MIN_Y)) * (1.0 / (MESH_Y_DIST));
-        return constrain(cy, 0, (GRID_MAX_POINTS_Y) - 1);   // -1 is appropriate if we want all movement to the Y_MAX
-      }                                                     // position. But with this defined this way, it is possible
-                                                            // to extrapolate off of this point even further out. Probably
-                                                            // that is OK because something else should be keeping that from
-                                                            // happening and should not be worried about at this level.
+    static int8_t find_closest_x_index(const float &x) {
+      const int8_t px = (x - (MESH_MIN_X) + (MESH_X_DIST) * 0.5) * (1.0 / (MESH_X_DIST));
+      return WITHIN(px, 0, GRID_MAX_POINTS_X - 1) ? px : -1;
+    }
 
-      static int8_t find_closest_x_index(const float &x) {
-        const int8_t px = (x - (MESH_MIN_X) + (MESH_X_DIST) * 0.5) * (1.0 / (MESH_X_DIST));
-        return WITHIN(px, 0, GRID_MAX_POINTS_X - 1) ? px : -1;
-      }
+    static int8_t find_closest_y_index(const float &y) {
+      const int8_t py = (y - (MESH_MIN_Y) + (MESH_Y_DIST) * 0.5) * (1.0 / (MESH_Y_DIST));
+      return WITHIN(py, 0, GRID_MAX_POINTS_Y - 1) ? py : -1;
+    }
 
-      static int8_t find_closest_y_index(const float &y) {
-        const int8_t py = (y - (MESH_MIN_Y) + (MESH_Y_DIST) * 0.5) * (1.0 / (MESH_Y_DIST));
-        return WITHIN(py, 0, GRID_MAX_POINTS_Y - 1) ? py : -1;
-      }
-
-      /**
-       *                           z2   --|
-       *                 z0        |      |
-       *                  |        |      + (z2-z1)
-       *   z1             |        |      |
-       * ---+-------------+--------+--  --|
-       *   a1            a0        a2
-       *    |<---delta_a---------->|
-       *
-       *  calc_z0 is the basis for all the Mesh Based correction. It is used to
-       *  find the expected Z Height at a position between two known Z-Height locations.
-       *
-       *  It is fairly expensive with its 4 floating point additions and 2 floating point
-       *  multiplications.
-       */
-      FORCE_INLINE static float calc_z0(const float &a0, const float &a1, const float &z1, const float &a2, const float &z2) {
-        return z1 + (z2 - z1) * (a0 - a1) / (a2 - a1);
-      }
-
-      /**
-       * z_correction_for_x_on_horizontal_mesh_line is an optimization for
-       * the case where the printer is making a vertical line that only crosses horizontal mesh lines.
-       */
-      inline static float z_correction_for_x_on_horizontal_mesh_line(const float &rx0, const int x1_i, const int yi) {
-        if (!WITHIN(x1_i, 0, GRID_MAX_POINTS_X - 1) || !WITHIN(yi, 0, GRID_MAX_POINTS_Y - 1)) {
-          #if ENABLED(DEBUG_LEVELING_FEATURE)
-            if (DEBUGGING(LEVELING)) {
-              serialprintPGM( !WITHIN(x1_i, 0, GRID_MAX_POINTS_X - 1) ? PSTR("x1_i") : PSTR("yi") );
-              SERIAL_ECHOPAIR(" out of bounds in z_correction_for_x_on_horizontal_mesh_line(rx0=", rx0);
-              SERIAL_ECHOPAIR(",x1_i=", x1_i);
-              SERIAL_ECHOPAIR(",yi=", yi);
-              SERIAL_CHAR(')');
-              SERIAL_EOL();
-            }
-          #endif
-          // The requested location is off the mesh. Return UBL_Z_RAISE_WHEN_OFF_MESH or NAN.
-          return (
-            #ifdef UBL_Z_RAISE_WHEN_OFF_MESH
-              UBL_Z_RAISE_WHEN_OFF_MESH
-            #else
-              NAN
-            #endif
-          );
-        }
-
-        const float xratio = (rx0 - mesh_index_to_xpos(x1_i)) * (1.0 / (MESH_X_DIST)),
-                    z1 = z_values[x1_i][yi];
-
-        return z1 + xratio * (z_values[min(x1_i, GRID_MAX_POINTS_X - 2) + 1][yi] - z1); // Don't allow x1_i+1 to be past the end of the array
-                                                                                        // If it is, it is clamped to the last element of the
-                                                                                        // z_values[][] array and no correction is applied.
-      }
-
-      //
-      // See comments above for z_correction_for_x_on_horizontal_mesh_line
-      //
-      inline static float z_correction_for_y_on_vertical_mesh_line(const float &ry0, const int xi, const int y1_i) {
-        if (!WITHIN(xi, 0, GRID_MAX_POINTS_X - 1) || !WITHIN(y1_i, 0, GRID_MAX_POINTS_Y - 1)) {
-          #if ENABLED(DEBUG_LEVELING_FEATURE)
-            if (DEBUGGING(LEVELING)) {
-              serialprintPGM( !WITHIN(xi, 0, GRID_MAX_POINTS_X - 1) ? PSTR("xi") : PSTR("y1_i") );
-              SERIAL_ECHOPAIR(" out of bounds in z_correction_for_y_on_vertical_mesh_line(ry0=", ry0);
-              SERIAL_ECHOPAIR(", xi=", xi);
-              SERIAL_ECHOPAIR(", y1_i=", y1_i);
-              SERIAL_CHAR(')');
-              SERIAL_EOL();
-            }
-          #endif
-           // The requested location is off the mesh. Return UBL_Z_RAISE_WHEN_OFF_MESH or NAN.
-          return (
-            #ifdef UBL_Z_RAISE_WHEN_OFF_MESH
-              UBL_Z_RAISE_WHEN_OFF_MESH
-            #else
-              NAN
-            #endif
-          );
-        }
-
-        const float yratio = (ry0 - mesh_index_to_ypos(y1_i)) * (1.0 / (MESH_Y_DIST)),
-                    z1 = z_values[xi][y1_i];
-
-        return z1 + yratio * (z_values[xi][min(y1_i, GRID_MAX_POINTS_Y - 2) + 1] - z1); // Don't allow y1_i+1 to be past the end of the array
-                                                                                        // If it is, it is clamped to the last element of the
-                                                                                        // z_values[][] array and no correction is applied.
-      }
-
-      /**
-       * This is the generic Z-Correction. It works anywhere within a Mesh Cell. It first
-       * does a linear interpolation along both of the bounding X-Mesh-Lines to find the
-       * Z-Height at both ends. Then it does a linear interpolation of these heights based
-       * on the Y position within the cell.
-       */
-      static float get_z_correction(const float &rx0, const float &ry0) {
-        const int8_t cx = get_cell_index_x(rx0),
-                     cy = get_cell_index_y(ry0); // return values are clamped
-
-       /**
-         * Check if the requested location is off the mesh.  If so, and
-         * UBL_Z_RAISE_WHEN_OFF_MESH is specified, that value is returned.
-         */
-        #ifdef UBL_Z_RAISE_WHEN_OFF_MESH
-          if (!WITHIN(rx0, MESH_MIN_X, MESH_MAX_X) || !WITHIN(ry0, MESH_MIN_Y, MESH_MAX_Y))
-            return UBL_Z_RAISE_WHEN_OFF_MESH;
-        #endif
-
-        const float z1 = calc_z0(rx0,
-                                 mesh_index_to_xpos(cx), z_values[cx][cy],
-                                 mesh_index_to_xpos(cx + 1), z_values[min(cx, GRID_MAX_POINTS_X - 2) + 1][cy]);
-
-        const float z2 = calc_z0(rx0,
-                                 mesh_index_to_xpos(cx), z_values[cx][min(cy, GRID_MAX_POINTS_Y - 2) + 1],
-                                 mesh_index_to_xpos(cx + 1), z_values[min(cx, GRID_MAX_POINTS_X - 2) + 1][min(cy, GRID_MAX_POINTS_Y - 2) + 1]);
-
-        float z0 = calc_z0(ry0,
-                           mesh_index_to_ypos(cy), z1,
-                           mesh_index_to_ypos(cy + 1), z2);
+    /**
+     *                           z2   --|
+     *                 z0        |      |
+     *                  |        |      + (z2-z1)
+     *   z1             |        |      |
+     * ---+-------------+--------+--  --|
+     *   a1            a0        a2
+     *    |<---delta_a---------->|
+     *
+     *  calc_z0 is the basis for all the Mesh Based correction. It is used to
+     *  find the expected Z Height at a position between two known Z-Height locations.
+     *
+     *  It is fairly expensive with its 4 floating point additions and 2 floating point
+     *  multiplications.
+     */
+    FORCE_INLINE static float calc_z0(const float &a0, const float &a1, const float &z1, const float &a2, const float &z2) {
+      return z1 + (z2 - z1) * (a0 - a1) / (a2 - a1);
+    }
 
+    /**
+     * z_correction_for_x_on_horizontal_mesh_line is an optimization for
+     * the case where the printer is making a vertical line that only crosses horizontal mesh lines.
+     */
+    inline static float z_correction_for_x_on_horizontal_mesh_line(const float &rx0, const int x1_i, const int yi) {
+      if (!WITHIN(x1_i, 0, GRID_MAX_POINTS_X - 1) || !WITHIN(yi, 0, GRID_MAX_POINTS_Y - 1)) {
         #if ENABLED(DEBUG_LEVELING_FEATURE)
-          if (DEBUGGING(MESH_ADJUST)) {
-            SERIAL_ECHOPAIR(" raw get_z_correction(", rx0);
-            SERIAL_CHAR(',');
-            SERIAL_ECHO(ry0);
-            SERIAL_ECHOPGM(") = ");
-            SERIAL_ECHO_F(z0, 6);
-          }
-        #endif
-
-        #if ENABLED(DEBUG_LEVELING_FEATURE)
-          if (DEBUGGING(MESH_ADJUST)) {
-            SERIAL_ECHOPGM(" >>>---> ");
-            SERIAL_ECHO_F(z0, 6);
+          if (DEBUGGING(LEVELING)) {
+            serialprintPGM( !WITHIN(x1_i, 0, GRID_MAX_POINTS_X - 1) ? PSTR("x1_i") : PSTR("yi") );
+            SERIAL_ECHOPAIR(" out of bounds in z_correction_for_x_on_horizontal_mesh_line(rx0=", rx0);
+            SERIAL_ECHOPAIR(",x1_i=", x1_i);
+            SERIAL_ECHOPAIR(",yi=", yi);
+            SERIAL_CHAR(')');
             SERIAL_EOL();
           }
         #endif
-
-        if (isnan(z0)) { // if part of the Mesh is undefined, it will show up as NAN
-          z0 = 0.0;      // in ubl.z_values[][] and propagate through the
-                         // calculations. If our correction is NAN, we throw it out
-                         // because part of the Mesh is undefined and we don't have the
-                         // information we need to complete the height correction.
-
-          #if ENABLED(DEBUG_LEVELING_FEATURE)
-            if (DEBUGGING(MESH_ADJUST)) {
-              SERIAL_ECHOPAIR("??? Yikes!  NAN in get_z_correction(", rx0);
-              SERIAL_CHAR(',');
-              SERIAL_ECHO(ry0);
-              SERIAL_CHAR(')');
-              SERIAL_EOL();
-            }
+        // The requested location is off the mesh. Return UBL_Z_RAISE_WHEN_OFF_MESH or NAN.
+        return (
+          #ifdef UBL_Z_RAISE_WHEN_OFF_MESH
+            UBL_Z_RAISE_WHEN_OFF_MESH
+          #else
+            NAN
           #endif
-        }
-        return z0;
-      }
-
-      FORCE_INLINE static float mesh_index_to_xpos(const uint8_t i) {
-        return i < GRID_MAX_POINTS_X ? pgm_read_float(&_mesh_index_to_xpos[i]) : MESH_MIN_X + i * (MESH_X_DIST);
-      }
-
-      FORCE_INLINE static float mesh_index_to_ypos(const uint8_t i) {
-        return i < GRID_MAX_POINTS_Y ? pgm_read_float(&_mesh_index_to_ypos[i]) : MESH_MIN_Y + i * (MESH_Y_DIST);
-      }
-
-      #if UBL_SEGMENTED
-        static bool prepare_segmented_line_to(const float (&rtarget)[XYZE], const float &feedrate);
-      #else
-        static void line_to_destination_cartesian(const float &fr, const uint8_t e);
-      #endif
-
-      #define _CMPZ(a,b) (z_values[a][b] == z_values[a][b+1])
-      #define CMPZ(a) (_CMPZ(a, 0) && _CMPZ(a, 1))
-      #define ZZER(a) (z_values[a][0] == 0)
-
-      FORCE_INLINE bool mesh_is_valid() {
-        return !(
-          (    CMPZ(0) && CMPZ(1) && CMPZ(2) // adjacent z values all equal?
-            && ZZER(0) && ZZER(1) && ZZER(2) // all zero at the edge?
-          )
-          || isnan(z_values[0][0])
         );
       }
-  }; // class unified_bed_leveling
 
-  extern unified_bed_leveling ubl;
+      const float xratio = (rx0 - mesh_index_to_xpos(x1_i)) * (1.0 / (MESH_X_DIST)),
+                  z1 = z_values[x1_i][yi];
 
-  FORCE_INLINE void gcode_G29() { ubl.G29(); }
+      return z1 + xratio * (z_values[min(x1_i, GRID_MAX_POINTS_X - 2) + 1][yi] - z1); // Don't allow x1_i+1 to be past the end of the array
+                                                                                      // If it is, it is clamped to the last element of the
+                                                                                      // z_values[][] array and no correction is applied.
+    }
+
+    //
+    // See comments above for z_correction_for_x_on_horizontal_mesh_line
+    //
+    inline static float z_correction_for_y_on_vertical_mesh_line(const float &ry0, const int xi, const int y1_i) {
+      if (!WITHIN(xi, 0, GRID_MAX_POINTS_X - 1) || !WITHIN(y1_i, 0, GRID_MAX_POINTS_Y - 1)) {
+        #if ENABLED(DEBUG_LEVELING_FEATURE)
+          if (DEBUGGING(LEVELING)) {
+            serialprintPGM( !WITHIN(xi, 0, GRID_MAX_POINTS_X - 1) ? PSTR("xi") : PSTR("y1_i") );
+            SERIAL_ECHOPAIR(" out of bounds in z_correction_for_y_on_vertical_mesh_line(ry0=", ry0);
+            SERIAL_ECHOPAIR(", xi=", xi);
+            SERIAL_ECHOPAIR(", y1_i=", y1_i);
+            SERIAL_CHAR(')');
+            SERIAL_EOL();
+          }
+        #endif
+         // The requested location is off the mesh. Return UBL_Z_RAISE_WHEN_OFF_MESH or NAN.
+        return (
+          #ifdef UBL_Z_RAISE_WHEN_OFF_MESH
+            UBL_Z_RAISE_WHEN_OFF_MESH
+          #else
+            NAN
+          #endif
+        );
+      }
+
+      const float yratio = (ry0 - mesh_index_to_ypos(y1_i)) * (1.0 / (MESH_Y_DIST)),
+                  z1 = z_values[xi][y1_i];
+
+      return z1 + yratio * (z_values[xi][min(y1_i, GRID_MAX_POINTS_Y - 2) + 1] - z1); // Don't allow y1_i+1 to be past the end of the array
+                                                                                      // If it is, it is clamped to the last element of the
+                                                                                      // z_values[][] array and no correction is applied.
+    }
+
+    /**
+     * This is the generic Z-Correction. It works anywhere within a Mesh Cell. It first
+     * does a linear interpolation along both of the bounding X-Mesh-Lines to find the
+     * Z-Height at both ends. Then it does a linear interpolation of these heights based
+     * on the Y position within the cell.
+     */
+    static float get_z_correction(const float &rx0, const float &ry0) {
+      const int8_t cx = get_cell_index_x(rx0),
+                   cy = get_cell_index_y(ry0); // return values are clamped
+
+     /**
+       * Check if the requested location is off the mesh.  If so, and
+       * UBL_Z_RAISE_WHEN_OFF_MESH is specified, that value is returned.
+       */
+      #ifdef UBL_Z_RAISE_WHEN_OFF_MESH
+        if (!WITHIN(rx0, MESH_MIN_X, MESH_MAX_X) || !WITHIN(ry0, MESH_MIN_Y, MESH_MAX_Y))
+          return UBL_Z_RAISE_WHEN_OFF_MESH;
+      #endif
+
+      const float z1 = calc_z0(rx0,
+                               mesh_index_to_xpos(cx), z_values[cx][cy],
+                               mesh_index_to_xpos(cx + 1), z_values[min(cx, GRID_MAX_POINTS_X - 2) + 1][cy]);
+
+      const float z2 = calc_z0(rx0,
+                               mesh_index_to_xpos(cx), z_values[cx][min(cy, GRID_MAX_POINTS_Y - 2) + 1],
+                               mesh_index_to_xpos(cx + 1), z_values[min(cx, GRID_MAX_POINTS_X - 2) + 1][min(cy, GRID_MAX_POINTS_Y - 2) + 1]);
+
+      float z0 = calc_z0(ry0,
+                         mesh_index_to_ypos(cy), z1,
+                         mesh_index_to_ypos(cy + 1), z2);
+
+      #if ENABLED(DEBUG_LEVELING_FEATURE)
+        if (DEBUGGING(MESH_ADJUST)) {
+          SERIAL_ECHOPAIR(" raw get_z_correction(", rx0);
+          SERIAL_CHAR(',');
+          SERIAL_ECHO(ry0);
+          SERIAL_ECHOPGM(") = ");
+          SERIAL_ECHO_F(z0, 6);
+        }
+      #endif
+
+      #if ENABLED(DEBUG_LEVELING_FEATURE)
+        if (DEBUGGING(MESH_ADJUST)) {
+          SERIAL_ECHOPGM(" >>>---> ");
+          SERIAL_ECHO_F(z0, 6);
+          SERIAL_EOL();
+        }
+      #endif
+
+      if (isnan(z0)) { // if part of the Mesh is undefined, it will show up as NAN
+        z0 = 0.0;      // in ubl.z_values[][] and propagate through the
+                       // calculations. If our correction is NAN, we throw it out
+                       // because part of the Mesh is undefined and we don't have the
+                       // information we need to complete the height correction.
+
+        #if ENABLED(DEBUG_LEVELING_FEATURE)
+          if (DEBUGGING(MESH_ADJUST)) {
+            SERIAL_ECHOPAIR("??? Yikes!  NAN in get_z_correction(", rx0);
+            SERIAL_CHAR(',');
+            SERIAL_ECHO(ry0);
+            SERIAL_CHAR(')');
+            SERIAL_EOL();
+          }
+        #endif
+      }
+      return z0;
+    }
+
+    FORCE_INLINE static float mesh_index_to_xpos(const uint8_t i) {
+      return i < GRID_MAX_POINTS_X ? pgm_read_float(&_mesh_index_to_xpos[i]) : MESH_MIN_X + i * (MESH_X_DIST);
+    }
+
+    FORCE_INLINE static float mesh_index_to_ypos(const uint8_t i) {
+      return i < GRID_MAX_POINTS_Y ? pgm_read_float(&_mesh_index_to_ypos[i]) : MESH_MIN_Y + i * (MESH_Y_DIST);
+    }
+
+    #if UBL_SEGMENTED
+      static bool prepare_segmented_line_to(const float (&rtarget)[XYZE], const float &feedrate);
+    #else
+      static void line_to_destination_cartesian(const float &fr, const uint8_t e);
+    #endif
+
+    #define _CMPZ(a,b) (z_values[a][b] == z_values[a][b+1])
+    #define CMPZ(a) (_CMPZ(a, 0) && _CMPZ(a, 1))
+    #define ZZER(a) (z_values[a][0] == 0)
+
+    FORCE_INLINE bool mesh_is_valid() {
+      return !(
+        (    CMPZ(0) && CMPZ(1) && CMPZ(2) // adjacent z values all equal?
+          && ZZER(0) && ZZER(1) && ZZER(2) // all zero at the edge?
+        )
+        || isnan(z_values[0][0])
+      );
+    }
+}; // class unified_bed_leveling
+
+extern unified_bed_leveling ubl;
+
+FORCE_INLINE void gcode_G29() { ubl.G29(); }
 
-#endif // AUTO_BED_LEVELING_UBL
 #endif // UNIFIED_BED_LEVELING_H