Use H0 by default with UBL_MESH_EDIT_MOVES_Z (#10428)

Marlin/src/feature/bedlevel/ubl/ubl_G29.cpp

@@ -210,8 +210,8 @@
    *                    adhesion.
    *
    *                    P4 moves to the closest Mesh Point (and/or the given X Y), raises the nozzle above the mesh height
-   *                    by the given 'H' offset (or default Z_CLEARANCE_BETWEEN_PROBES), and waits while the controller is
-   *                    used to adjust the nozzle height. On click the displayed height is saved in the mesh.
+   *                    by the given 'H' offset (or default 0), and waits while the controller is used to adjust the nozzle
+   *                    height. On click the displayed height is saved in the mesh.
    *
    *                    Start Phase 4 at a specific location with X and Y. Adjust a specific number of Mesh Points with
    *                    the 'R' (Repeat) parameter. (If 'R' is left out, the whole matrix is assumed.) This command can be
@@ -1351,9 +1351,8 @@
         g29_repetition_cnt = 1;   // do exactly one mesh location. Otherwise use what the parser decided.
 
       #if ENABLED(UBL_MESH_EDIT_MOVES_Z)
-        const bool is_offset = parser.seen('H');
-        const float h_offset = is_offset ? parser.value_linear_units() : Z_CLEARANCE_BETWEEN_PROBES;
-        if (is_offset && !WITHIN(h_offset, 0, 10)) {
+        const float h_offset = parser.seenval('H') ? parser.value_linear_units() : 0;
+        if (!WITHIN(h_offset, 0, 10)) {
           SERIAL_PROTOCOLLNPGM("Offset out of bounds. (0 to 10mm)\n");
           return;
         }
@@ -1369,63 +1368,63 @@
       save_ubl_active_state_and_disable();
 
       LCD_MESSAGEPGM(MSG_UBL_FINE_TUNE_MESH);
+      lcd_external_control = true;                                  // Take over control of the LCD encoder
 
-      do_blocking_move_to(rx, ry, Z_CLEARANCE_BETWEEN_PROBES);
+      do_blocking_move_to(rx, ry, Z_CLEARANCE_BETWEEN_PROBES);      // Move to the given XY with probe clearance
+
+      #if ENABLED(UBL_MESH_EDIT_MOVES_Z)
+        do_blocking_move_to_z(h_offset);                            // Move Z to the given 'H' offset
+      #endif
 
       uint16_t not_done[16];
       memset(not_done, 0xFF, sizeof(not_done));
       do {
         location = find_closest_mesh_point_of_type(SET_IN_BITMAP, rx, ry, USE_NOZZLE_AS_REFERENCE, not_done);
 
-        if (location.x_index < 0) break; // stop when we can't find any more reachable points.
+        if (location.x_index < 0) break;                            // Stop when there are no more reachable points
 
-        bitmap_clear(not_done, location.x_index, location.y_index); // Mark this location as 'adjusted' so we will find a
-                                                                    // different location the next time through the loop
+        bitmap_clear(not_done, location.x_index, location.y_index); // Mark this location as 'adjusted' so a new
+                                                                    // location is used on the next loop
 
         const float rawx = mesh_index_to_xpos(location.x_index),
                     rawy = mesh_index_to_ypos(location.y_index);
 
-        if (!position_is_reachable(rawx, rawy)) // SHOULD NOT OCCUR because find_closest_mesh_point_of_type will only return reachable
-          break;
+        //if (!position_is_reachable(rawx, rawy)) break;            // SHOULD NOT OCCUR because find_closest_mesh_point_of_type will only return reachable
 
-        do_blocking_move_to(rawx, rawy, Z_CLEARANCE_BETWEEN_PROBES); // Move the nozzle to the edit point
+        do_blocking_move_to(rawx, rawy, Z_CLEARANCE_BETWEEN_PROBES); // Move the nozzle to the edit point with probe clearance
+
+        #if ENABLED(UBL_MESH_EDIT_MOVES_Z)
+          do_blocking_move_to_z(h_offset);                          // Move Z to the given 'H' offset before editing
+        #endif
 
         KEEPALIVE_STATE(PAUSED_FOR_USER);
-        lcd_external_control = true;
 
-        if (do_ubl_mesh_map) display_map(g29_map_type);  // show the user which point is being adjusted
+        if (do_ubl_mesh_map) display_map(g29_map_type);             // Display the current point
 
         lcd_refresh();
 
         float new_z = z_values[location.x_index][location.y_index];
-        if (isnan(new_z)) new_z = 0.0;          // Set invalid mesh points to 0.0 so they can be edited
-        new_z = FLOOR(new_z * 1000.0) * 0.001;  // Chop off digits after the 1000ths place
+        if (isnan(new_z)) new_z = 0.0;                              // Invalid points begin at 0
+        new_z = FLOOR(new_z * 1000.0) * 0.001;                      // Chop off digits after the 1000ths place
 
         lcd_mesh_edit_setup(new_z);
 
         do {
           new_z = lcd_mesh_edit();
           #if ENABLED(UBL_MESH_EDIT_MOVES_Z)
-            do_blocking_move_to_z(h_offset + new_z); // Move the nozzle as the point is edited
+            do_blocking_move_to_z(h_offset + new_z);                // Move the nozzle as the point is edited
           #endif
           idle();
-          SERIAL_FLUSH(); // Prevent host M105 buffer overrun.
+          SERIAL_FLUSH();                                           // Prevent host M105 buffer overrun.
         } while (!is_lcd_clicked());
 
-        if (!lcd_map_control) lcd_return_to_status();
-
-        // The technique used here generates a race condition for the encoder click.
-        // It could get detected in lcd_mesh_edit (actually _lcd_mesh_fine_tune) or here.
-        // Let's work on specifying a proper API for the LCD ASAP, OK?
-        lcd_external_control = true;
-
-        if (click_and_hold(abort_fine_tune))
-          goto FINE_TUNE_EXIT;
+        if (!lcd_map_control) lcd_return_to_status();               // Just editing a single point? Return to status
 
-        safe_delay(20);                       // We don't want any switch noise.
+        if (click_and_hold(abort_fine_tune)) goto FINE_TUNE_EXIT;   // If the click is held down, abort editing
 
-        z_values[location.x_index][location.y_index] = new_z;
+        z_values[location.x_index][location.y_index] = new_z;       // Save the updated Z value
 
+        safe_delay(20);                                             // No switch noise
         lcd_refresh();
 
       } while (location.x_index >= 0 && --g29_repetition_cnt > 0);