Only constrain motion on homed axes (#16533)

Co-authored-by: Scott Lahteine <thinkyhead@users.noreply.github.com>

Marlin/src/module/motion.cpp

    */
   void apply_motion_limits(xyz_pos_t &target) {
 
-    if (!soft_endstops_enabled || !all_axes_homed()) return;
+    if (!soft_endstops_enabled) return;
 
     #if IS_KINEMATIC
 
+      #if ENABLED(DELTA)
+        if (!all_axes_homed()) return;
+      #endif
+
       #if HAS_HOTEND_OFFSET && ENABLED(DELTA)
         // The effector center position will be the target minus the hotend offset.
         const xy_pos_t offs = hotend_offset[active_extruder];
         constexpr xy_pos_t offs{0};
       #endif
 
-      const float dist_2 = HYPOT2(target.x - offs.x, target.y - offs.y);
-      if (dist_2 > delta_max_radius_2)
-        target *= delta_max_radius / SQRT(dist_2); // 200 / 300 = 0.66
+      if (true
+        #if IS_SCARA
+          && TEST(axis_homed, X_AXIS) && TEST(axis_homed, Y_AXIS)
+        #endif
+      ) {
+        const float dist_2 = HYPOT2(target.x - offs.x, target.y - offs.y);
+        if (dist_2 > delta_max_radius_2)
+          target *= delta_max_radius / SQRT(dist_2); // 200 / 300 = 0.66
+      }
 
     #else
 
-      #if !HAS_SOFTWARE_ENDSTOPS || ENABLED(MIN_SOFTWARE_ENDSTOP_X)
-        NOLESS(target.x, soft_endstop.min.x);
-      #endif
-      #if !HAS_SOFTWARE_ENDSTOPS || ENABLED(MAX_SOFTWARE_ENDSTOP_X)
-        NOMORE(target.x, soft_endstop.max.x);
-      #endif
-      #if !HAS_SOFTWARE_ENDSTOPS || ENABLED(MIN_SOFTWARE_ENDSTOP_Y)
-        NOLESS(target.y, soft_endstop.min.y);
-      #endif
-      #if !HAS_SOFTWARE_ENDSTOPS || ENABLED(MAX_SOFTWARE_ENDSTOP_Y)
-        NOMORE(target.y, soft_endstop.max.y);
-      #endif
+      if (TEST(axis_homed, X_AXIS)) {
+        #if !HAS_SOFTWARE_ENDSTOPS || ENABLED(MIN_SOFTWARE_ENDSTOP_X)
+          NOLESS(target.x, soft_endstop.min.x);
+        #endif
+        #if !HAS_SOFTWARE_ENDSTOPS || ENABLED(MAX_SOFTWARE_ENDSTOP_X)
+          NOMORE(target.x, soft_endstop.max.x);
+        #endif
+      }
 
-    #endif
+      if (TEST(axis_homed, Y_AXIS)) {
+        #if !HAS_SOFTWARE_ENDSTOPS || ENABLED(MIN_SOFTWARE_ENDSTOP_Y)
+          NOLESS(target.y, soft_endstop.min.y);
+        #endif
+        #if !HAS_SOFTWARE_ENDSTOPS || ENABLED(MAX_SOFTWARE_ENDSTOP_Y)
+          NOMORE(target.y, soft_endstop.max.y);
+        #endif
+      }
 
-    #if !HAS_SOFTWARE_ENDSTOPS || ENABLED(MIN_SOFTWARE_ENDSTOP_Z)
-      NOLESS(target.z, soft_endstop.min.z);
-    #endif
-    #if !HAS_SOFTWARE_ENDSTOPS || ENABLED(MAX_SOFTWARE_ENDSTOP_Z)
-      NOMORE(target.z, soft_endstop.max.z);
     #endif
+
+    if (TEST(axis_homed, Z_AXIS)) {
+      #if !HAS_SOFTWARE_ENDSTOPS || ENABLED(MIN_SOFTWARE_ENDSTOP_Z)
+        NOLESS(target.z, soft_endstop.min.z);
+      #endif
+      #if !HAS_SOFTWARE_ENDSTOPS || ENABLED(MAX_SOFTWARE_ENDSTOP_Z)
+        NOMORE(target.z, soft_endstop.max.z);
+      #endif
+    }
   }
 
 #endif // HAS_SOFTWARE_ENDSTOPS

Marlin/src/module/motion.h

 // Axis homed and known-position states
 extern uint8_t axis_homed, axis_known_position;
 constexpr uint8_t xyz_bits = _BV(X_AXIS) | _BV(Y_AXIS) | _BV(Z_AXIS);
+FORCE_INLINE bool no_axes_homed() { return !axis_homed; }
 FORCE_INLINE bool all_axes_homed() { return (axis_homed & xyz_bits) == xyz_bits; }
 FORCE_INLINE bool all_axes_known() { return (axis_known_position & xyz_bits) == xyz_bits; }
 FORCE_INLINE void set_all_unhomed() { axis_homed = 0; }