Implement Dry-Run mode in G29

It just probe all the bed without appliying the matrix.
Useful after a first G29 to check the topology.

Marlin/Marlin_main.cpp

@@ -1168,6 +1168,7 @@ static void run_z_probe() {
     zPosition += home_retract_mm(Z_AXIS);
     plan_buffer_line(current_position[X_AXIS], current_position[Y_AXIS], zPosition, current_position[E_AXIS], feedrate/60, active_extruder);
     st_synchronize();
+    endstops_hit_on_purpose();
 
     // move back down slowly to find bed
     
@@ -1185,6 +1186,7 @@ static void run_z_probe() {
     zPosition -= home_retract_mm(Z_AXIS) * 2;
     plan_buffer_line(current_position[X_AXIS], current_position[Y_AXIS], zPosition, current_position[E_AXIS], feedrate/60, active_extruder);
     st_synchronize();
+    endstops_hit_on_purpose();
 
     current_position[Z_AXIS] = st_get_position_mm(Z_AXIS);
     // make sure the planner knows where we are as it may be a bit different than we last said to move to
@@ -1389,11 +1391,11 @@ static float probe_pt(float x, float y, float z_before, ProbeAction retract_acti
   if (verbose_level > 2) {
     SERIAL_PROTOCOLPGM(MSG_BED);
     SERIAL_PROTOCOLPGM(" X: ");
-    SERIAL_PROTOCOL(x + 0.0001);
+    SERIAL_PROTOCOL_F(x, 3);
     SERIAL_PROTOCOLPGM(" Y: ");
-    SERIAL_PROTOCOL(y + 0.0001);
+    SERIAL_PROTOCOL_F(y, 3);
     SERIAL_PROTOCOLPGM(" Z: ");
-    SERIAL_PROTOCOL(measured_z + 0.0001);
+    SERIAL_PROTOCOL_F(measured_z, 3);
     SERIAL_EOL;
   }
   return measured_z;
@@ -2109,6 +2111,9 @@ inline void gcode_G28() {
    *
    *  S  Set the XY travel speed between probe points (in mm/min)
    *
+   *  D  Dry-Run mode. Just evaluate the bed Topology - It does not apply or clean the rotation Matrix
+   *     Useful to check the topology after a first run of G29.
+   *
    *  V  Set the verbose level (0-4). Example: "G29 V3"
    *
    *  T  Generate a Bed Topology Report. Example: "G29 P5 T" for a detailed report.
@@ -2150,6 +2155,7 @@ inline void gcode_G28() {
       }
     }
 
+    bool dryrun = code_seen('D') || code_seen('d');
     bool enhanced_g29 = code_seen('E') || code_seen('e');
 
     #ifdef AUTO_BED_LEVELING_GRID
@@ -2159,7 +2165,10 @@ inline void gcode_G28() {
     #endif
 
       if (verbose_level > 0)
+      {
         SERIAL_PROTOCOLPGM("G29 Auto Bed Leveling\n");
+        if (dryrun) SERIAL_ECHOLN("Running in DRY-RUN mode");
+      }
 
       int auto_bed_leveling_grid_points = AUTO_BED_LEVELING_GRID_POINTS;
       #ifndef DELTA
@@ -2216,6 +2225,8 @@ inline void gcode_G28() {
 
     st_synchronize();
 
+    if (!dryrun)
+    {
       #ifdef DELTA
         reset_bed_level();
       #else
@@ -2226,11 +2237,14 @@ inline void gcode_G28() {
       plan_bed_level_matrix.set_to_identity();
       vector_3 uncorrected_position = plan_get_position();
 //    uncorrected_position.debug("position during G29");
+
       current_position[X_AXIS] = uncorrected_position.x;
       current_position[Y_AXIS] = uncorrected_position.y;
       current_position[Z_AXIS] = uncorrected_position.z;
       plan_set_position(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS]);
+
       #endif
+    }
     
     setup_for_endstop_move();
 
@@ -2381,12 +2395,12 @@ inline void gcode_G28() {
       } //do_topography_map
 
 
-      set_bed_level_equation_lsq(plane_equation_coefficients);
+      if (!dryrun) set_bed_level_equation_lsq(plane_equation_coefficients);
       free(plane_equation_coefficients);
-    #else
+    #else //Delta
-      extrapolate_unprobed_bed_level();
+      if (!dryrun) extrapolate_unprobed_bed_level();
       print_bed_level();
-    #endif
+    #endif //Delta
 
     #else // !AUTO_BED_LEVELING_GRID
 
@@ -2405,17 +2419,18 @@ inline void gcode_G28() {
         z_at_pt_3 = probe_pt(ABL_PROBE_PT_3_X, ABL_PROBE_PT_3_Y, current_position[Z_AXIS] + Z_RAISE_BETWEEN_PROBINGS, ProbeEngageAndRetract, verbose_level);
       }
       clean_up_after_endstop_move();
-      set_bed_level_equation_3pts(z_at_pt_1, z_at_pt_2, z_at_pt_3);
+      if (!dryrun) set_bed_level_equation_3pts(z_at_pt_1, z_at_pt_2, z_at_pt_3);
 
     #endif // !AUTO_BED_LEVELING_GRID
 
   #ifndef DELTA
-    if (verbose_level > 0)
+    if (verbose_level > 0) plan_bed_level_matrix.debug(" \n\nBed Level Correction Matrix:");
-      plan_bed_level_matrix.debug(" \n\nBed Level Correction Matrix:");
 
     // Correct the Z height difference from z-probe position and hotend tip position.
     // The Z height on homing is measured by Z-Probe, but the probe is quite far from the hotend.
     // When the bed is uneven, this height must be corrected.
+    if (!dryrun)
+    {
       real_z = float(st_get_position(Z_AXIS)) / axis_steps_per_unit[Z_AXIS];  //get the real Z (since the auto bed leveling is already correcting the plane)
       x_tmp = current_position[X_AXIS] + X_PROBE_OFFSET_FROM_EXTRUDER;
       y_tmp = current_position[Y_AXIS] + Y_PROBE_OFFSET_FROM_EXTRUDER;
@@ -2424,6 +2439,7 @@ inline void gcode_G28() {
       apply_rotation_xyz(plan_bed_level_matrix, x_tmp, y_tmp, z_tmp);         //Apply the correction sending the probe offset
       current_position[Z_AXIS] = z_tmp - real_z + current_position[Z_AXIS];   //The difference is added to current position and sent to planner.
       plan_set_position(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS]);
+    }
   #endif
 
   #ifdef Z_PROBE_SLED