Add an option to segment leveled moves

Marlin/Configuration.h

   // The height can be set with M420 Z<height>
   #define ENABLE_LEVELING_FADE_HEIGHT
 
+  // For Cartesian machines, instead of dividing moves on mesh boundaries,
+  // split up moves into short segments like a Delta.
+  #define SEGMENT_LEVELED_MOVES
+  #define LEVELED_SEGMENT_LENGTH 5.0 // (mm) Length of all segments (except the last one)
+
   /**
    * Enable the G26 Mesh Validation Pattern tool.
    */

Marlin/src/feature/bedlevel/abl/abl.cpp

   return offset;
 }
 
-#if !IS_KINEMATIC
+#if IS_CARTESIAN && DISABLED(SEGMENT_LEVELED_MOVES)
 
   #define CELL_INDEX(A,V) ((V - bilinear_start[A##_AXIS]) * ABL_BG_FACTOR(A##_AXIS))
 
     bilinear_line_to_destination(fr_mm_s, x_splits, y_splits);
   }
 
-#endif // !IS_KINEMATIC
+#endif // IS_CARTESIAN && !SEGMENT_LEVELED_MOVES
 
 #endif // AUTO_BED_LEVELING_BILINEAR

Marlin/src/feature/bedlevel/abl/abl.h

     void bed_level_virt_interpolate();
   #endif
 
-  #if !IS_KINEMATIC
+  #if IS_CARTESIAN && DISABLED(SEGMENT_LEVELED_MOVES)
     void bilinear_line_to_destination(const float fr_mm_s, uint16_t x_splits=0xFFFF, uint16_t y_splits=0xFFFF);
   #endif
 

Marlin/src/feature/bedlevel/mbl/mesh_bed_leveling.cpp

     ZERO(z_values);
   }
 
-  /**
-   * Prepare a mesh-leveled linear move in a Cartesian setup,
-   * splitting the move where it crosses mesh borders.
-   */
-  void mesh_line_to_destination(const float fr_mm_s, uint8_t x_splits, uint8_t y_splits) {
-    int cx1 = mbl.cell_index_x(current_position[X_AXIS]),
-        cy1 = mbl.cell_index_y(current_position[Y_AXIS]),
-        cx2 = mbl.cell_index_x(destination[X_AXIS]),
-        cy2 = mbl.cell_index_y(destination[Y_AXIS]);
-    NOMORE(cx1, GRID_MAX_POINTS_X - 2);
-    NOMORE(cy1, GRID_MAX_POINTS_Y - 2);
-    NOMORE(cx2, GRID_MAX_POINTS_X - 2);
-    NOMORE(cy2, GRID_MAX_POINTS_Y - 2);
-
-    if (cx1 == cx2 && cy1 == cy2) {
-      // Start and end on same mesh square
-      buffer_line_to_destination(fr_mm_s);
-      set_current_from_destination();
-      return;
+  #if IS_CARTESIAN && DISABLED(SEGMENT_LEVELED_MOVES)
+
+    /**
+     * Prepare a mesh-leveled linear move in a Cartesian setup,
+     * splitting the move where it crosses mesh borders.
+     */
+    void mesh_line_to_destination(const float fr_mm_s, uint8_t x_splits, uint8_t y_splits) {
+      int cx1 = mbl.cell_index_x(current_position[X_AXIS]),
+          cy1 = mbl.cell_index_y(current_position[Y_AXIS]),
+          cx2 = mbl.cell_index_x(destination[X_AXIS]),
+          cy2 = mbl.cell_index_y(destination[Y_AXIS]);
+      NOMORE(cx1, GRID_MAX_POINTS_X - 2);
+      NOMORE(cy1, GRID_MAX_POINTS_Y - 2);
+      NOMORE(cx2, GRID_MAX_POINTS_X - 2);
+      NOMORE(cy2, GRID_MAX_POINTS_Y - 2);
+
+      if (cx1 == cx2 && cy1 == cy2) {
+        // Start and end on same mesh square
+        buffer_line_to_destination(fr_mm_s);
+        set_current_from_destination();
+        return;
+      }
+
+      #define MBL_SEGMENT_END(A) (current_position[A ##_AXIS] + (destination[A ##_AXIS] - current_position[A ##_AXIS]) * normalized_dist)
+
+      float normalized_dist, end[XYZE];
+
+      // Split at the left/front border of the right/top square
+      const int8_t gcx = max(cx1, cx2), gcy = max(cy1, cy2);
+      if (cx2 != cx1 && TEST(x_splits, gcx)) {
+        COPY(end, destination);
+        destination[X_AXIS] = mbl.index_to_xpos[gcx];
+        normalized_dist = (destination[X_AXIS] - current_position[X_AXIS]) / (end[X_AXIS] - current_position[X_AXIS]);
+        destination[Y_AXIS] = MBL_SEGMENT_END(Y);
+        CBI(x_splits, gcx);
+      }
+      else if (cy2 != cy1 && TEST(y_splits, gcy)) {
+        COPY(end, destination);
+        destination[Y_AXIS] = mbl.index_to_ypos[gcy];
+        normalized_dist = (destination[Y_AXIS] - current_position[Y_AXIS]) / (end[Y_AXIS] - current_position[Y_AXIS]);
+        destination[X_AXIS] = MBL_SEGMENT_END(X);
+        CBI(y_splits, gcy);
+      }
+      else {
+        // Already split on a border
+        buffer_line_to_destination(fr_mm_s);
+        set_current_from_destination();
+        return;
+      }
+
+      destination[Z_AXIS] = MBL_SEGMENT_END(Z);
+      destination[E_AXIS] = MBL_SEGMENT_END(E);
+
+      // Do the split and look for more borders
+      mesh_line_to_destination(fr_mm_s, x_splits, y_splits);
+
+      // Restore destination from stack
+      COPY(destination, end);
+      mesh_line_to_destination(fr_mm_s, x_splits, y_splits);
     }
 
-    #define MBL_SEGMENT_END(A) (current_position[A ##_AXIS] + (destination[A ##_AXIS] - current_position[A ##_AXIS]) * normalized_dist)
-
-    float normalized_dist, end[XYZE];
-
-    // Split at the left/front border of the right/top square
-    const int8_t gcx = max(cx1, cx2), gcy = max(cy1, cy2);
-    if (cx2 != cx1 && TEST(x_splits, gcx)) {
-      COPY(end, destination);
-      destination[X_AXIS] = mbl.index_to_xpos[gcx];
-      normalized_dist = (destination[X_AXIS] - current_position[X_AXIS]) / (end[X_AXIS] - current_position[X_AXIS]);
-      destination[Y_AXIS] = MBL_SEGMENT_END(Y);
-      CBI(x_splits, gcx);
-    }
-    else if (cy2 != cy1 && TEST(y_splits, gcy)) {
-      COPY(end, destination);
-      destination[Y_AXIS] = mbl.index_to_ypos[gcy];
-      normalized_dist = (destination[Y_AXIS] - current_position[Y_AXIS]) / (end[Y_AXIS] - current_position[Y_AXIS]);
-      destination[X_AXIS] = MBL_SEGMENT_END(X);
-      CBI(y_splits, gcy);
-    }
-    else {
-      // Already split on a border
-      buffer_line_to_destination(fr_mm_s);
-      set_current_from_destination();
-      return;
-    }
-
-    destination[Z_AXIS] = MBL_SEGMENT_END(Z);
-    destination[E_AXIS] = MBL_SEGMENT_END(E);
-
-    // Do the split and look for more borders
-    mesh_line_to_destination(fr_mm_s, x_splits, y_splits);
-
-    // Restore destination from stack
-    COPY(destination, end);
-    mesh_line_to_destination(fr_mm_s, x_splits, y_splits);
-  }
+  #endif // IS_CARTESIAN && !SEGMENT_LEVELED_MOVES
 
   void mbl_mesh_report() {
     SERIAL_PROTOCOLLNPGM("Num X,Y: " STRINGIFY(GRID_MAX_POINTS_X) "," STRINGIFY(GRID_MAX_POINTS_Y));

Marlin/src/feature/bedlevel/mbl/mesh_bed_leveling.h

 extern mesh_bed_leveling mbl;
 
 // Support functions, which may be embedded in the class later
-
-void mesh_line_to_destination(const float fr_mm_s, uint8_t x_splits=0xFF, uint8_t y_splits=0xFF);
+#if IS_CARTESIAN && DISABLED(SEGMENT_LEVELED_MOVES)
+  void mesh_line_to_destination(const float fr_mm_s, uint8_t x_splits=0xFF, uint8_t y_splits=0xFF);
+#endif
 
 void mbl_mesh_report();
 

Marlin/src/inc/Conditionals_post.h

 /**
  * Set granular options based on the specific type of leveling
  */
-#define UBL_DELTA  (ENABLED(AUTO_BED_LEVELING_UBL) && (ENABLED(DELTA) || ENABLED(UBL_GRANULAR_SEGMENTATION_FOR_CARTESIAN)))
+#define UBL_DELTA  (ENABLED(AUTO_BED_LEVELING_UBL) && (ENABLED(DELTA) || ENABLED(SEGMENT_LEVELED_MOVES)))
 #define ABL_PLANAR (ENABLED(AUTO_BED_LEVELING_LINEAR) || ENABLED(AUTO_BED_LEVELING_3POINT))
 #define ABL_GRID   (ENABLED(AUTO_BED_LEVELING_LINEAR) || ENABLED(AUTO_BED_LEVELING_BILINEAR))
 #define OLDSCHOOL_ABL         (ABL_PLANAR || ABL_GRID)
   #define PROBE_BED_HEIGHT abs(BACK_PROBE_BED_POSITION - (FRONT_PROBE_BED_POSITION))
 #endif
 
+#if ENABLED(SEGMENT_LEVELED_MOVES) && !defined(LEVELED_SEGMENT_LENGTH)
+  #define LEVELED_SEGMENT_LENGTH 5
+#endif
+
 /**
  * Bed Probing rectangular bounds
  * These can be further constrained in code for Delta and SCARA

Marlin/src/inc/SanityCheck.h

   #error "ENABLE_MESH_EDIT_GFX_OVERLAY is now MESH_EDIT_GFX_OVERLAY. Please update your configuration."
 #elif defined(BABYSTEP_ZPROBE_GFX_REVERSE)
   #error "BABYSTEP_ZPROBE_GFX_REVERSE is now set by OVERLAY_GFX_REVERSE. Please update your configurations."
+#elif defined(UBL_GRANULAR_SEGMENTATION_FOR_CARTESIAN)
+  #error "UBL_GRANULAR_SEGMENTATION_FOR_CARTESIAN is now SEGMENT_LEVELED_MOVES. Please update your configuration."
 #endif
 
 /**

Marlin/src/module/motion.cpp

     // Get the top feedrate of the move in the XY plane
     const float _feedrate_mm_s = MMS_SCALED(feedrate_mm_s);
 
+    const float xdiff = rtarget[X_AXIS] - current_position[X_AXIS],
+                ydiff = rtarget[Y_AXIS] - current_position[Y_AXIS];
+
     // If the move is only in Z/E don't split up the move
-    if (rtarget[X_AXIS] == current_position[X_AXIS] && rtarget[Y_AXIS] == current_position[Y_AXIS]) {
+    if (!xdiff && !ydiff) {
       planner.buffer_line_kinematic(rtarget, _feedrate_mm_s, active_extruder);
       return false;
     }
     // Fail if attempting move outside printable radius
     if (!position_is_reachable(rtarget[X_AXIS], rtarget[Y_AXIS])) return true;
 
-    // Get the cartesian distances moved in XYZE
-    const float difference[XYZE] = {
-      rtarget[X_AXIS] - current_position[X_AXIS],
-      rtarget[Y_AXIS] - current_position[Y_AXIS],
-      rtarget[Z_AXIS] - current_position[Z_AXIS],
-      rtarget[E_AXIS] - current_position[E_AXIS]
-    };
+    // Remaining cartesian distances
+    const float zdiff = rtarget[Z_AXIS] - current_position[Z_AXIS],
+                ediff = rtarget[E_AXIS] - current_position[E_AXIS];
 
     // Get the linear distance in XYZ
-    float cartesian_mm = SQRT(sq(difference[X_AXIS]) + sq(difference[Y_AXIS]) + sq(difference[Z_AXIS]));
+    float cartesian_mm = SQRT(sq(xdiff) + sq(ydiff) + sq(zdiff));
 
     // If the move is very short, check the E move distance
-    if (UNEAR_ZERO(cartesian_mm)) cartesian_mm = FABS(difference[E_AXIS]);
+    if (UNEAR_ZERO(cartesian_mm)) cartesian_mm = FABS(ediff);
 
     // No E move either? Game over.
     if (UNEAR_ZERO(cartesian_mm)) return true;
     // The approximate length of each segment
     const float inv_segments = 1.0 / float(segments),
                 segment_distance[XYZE] = {
-                  difference[X_AXIS] * inv_segments,
-                  difference[Y_AXIS] * inv_segments,
-                  difference[Z_AXIS] * inv_segments,
-                  difference[E_AXIS] * inv_segments
+                  xdiff * inv_segments,
+                  ydiff * inv_segments,
+                  zdiff * inv_segments,
+                  ediff * inv_segments
                 };
 
     // SERIAL_ECHOPAIR("mm=", cartesian_mm);
 
 #else // !IS_KINEMATIC
 
+  #if ENABLED(SEGMENT_LEVELED_MOVES)
+
+    /**
+     * Prepare a segmented move on a CARTESIAN setup.
+     *
+     * This calls planner.buffer_line several times, adding
+     * small incremental moves. This allows the planner to
+     * apply more detailed bed leveling to the full move.
+     */
+    inline void segmented_line_to_destination(const float &fr_mm_s, const float segment_size=LEVELED_SEGMENT_LENGTH) {
+
+      const float xdiff = destination[X_AXIS] - current_position[X_AXIS],
+                  ydiff = destination[Y_AXIS] - current_position[Y_AXIS];
+
+      // If the move is only in Z/E don't split up the move
+      if (!xdiff && !ydiff) {
+        planner.buffer_line_kinematic(destination, fr_mm_s, active_extruder);
+        return;
+      }
+
+      // Remaining cartesian distances
+      const float zdiff = destination[Z_AXIS] - current_position[Z_AXIS],
+                  ediff = destination[E_AXIS] - current_position[E_AXIS];
+
+      // Get the linear distance in XYZ
+      // If the move is very short, check the E move distance
+      // No E move either? Game over.
+      float cartesian_mm = SQRT(sq(xdiff) + sq(ydiff) + sq(zdiff));
+      if (UNEAR_ZERO(cartesian_mm)) cartesian_mm = FABS(ediff);
+      if (UNEAR_ZERO(cartesian_mm)) return;
+
+      // The length divided by the segment size
+      // At least one segment is required
+      uint16_t segments = cartesian_mm / segment_size;
+      NOLESS(segments, 1);
+
+      // The approximate length of each segment
+      const float inv_segments = 1.0 / float(segments),
+                  segment_distance[XYZE] = {
+                    xdiff * inv_segments,
+                    ydiff * inv_segments,
+                    zdiff * inv_segments,
+                    ediff * inv_segments
+                  };
+
+      // SERIAL_ECHOPAIR("mm=", cartesian_mm);
+      // SERIAL_ECHOLNPAIR(" segments=", segments);
+
+      // Drop one segment so the last move is to the exact target.
+      // If there's only 1 segment, loops will be skipped entirely.
+      --segments;
+
+      // Get the raw current position as starting point
+      float raw[XYZE];
+      COPY(raw, current_position);
+
+      // Calculate and execute the segments
+      for (uint16_t s = segments + 1; --s;) {
+        static millis_t next_idle_ms = millis() + 200UL;
+        thermalManager.manage_heater();  // This returns immediately if not really needed.
+        if (ELAPSED(millis(), next_idle_ms)) {
+          next_idle_ms = millis() + 200UL;
+          idle();
+        }
+        LOOP_XYZE(i) raw[i] += segment_distance[i];
+        planner.buffer_line_kinematic(raw, fr_mm_s, active_extruder);
+      }
+
+      // Since segment_distance is only approximate,
+      // the final move must be to the exact destination.
+      planner.buffer_line_kinematic(destination, fr_mm_s, active_extruder);
+    }
+
+  #endif // SEGMENT_LEVELED_MOVES
+
   /**
    * Prepare a linear move in a Cartesian setup.
    *
    */
   inline bool prepare_move_to_destination_cartesian() {
     #if HAS_MESH
-      if (planner.leveling_active) {
+      if (planner.leveling_active && planner.leveling_active_at_z(destination[Z_AXIS])) {
         #if ENABLED(AUTO_BED_LEVELING_UBL)
           ubl.line_to_destination_cartesian(MMS_SCALED(feedrate_mm_s), active_extruder);  // UBL's motion routine needs to know about
           return true;                                                                    // all moves, including Z-only moves.
+        #elif ENABLED(SEGMENT_LEVELED_MOVES)
+          segmented_line_to_destination(MMS_SCALED(feedrate_mm_s));
+          return false;
         #else
           /**
            * For MBL and ABL-BILINEAR only segment moves when X or Y are involved.