From c6494e9010857faee96f798e7d7fd197169a6563 Mon Sep 17 00:00:00 2001
From: vovodroid <vovodroid@users.noreply.github.com>
Date: Fri, 26 Dec 2025 21:26:30 +0200
Subject: [PATCH] Add NLE support to FTM

---
 Marlin/src/inc/SanityCheck.h    |  4 +---
 Marlin/src/inc/Warnings.cpp     |  3 ---
 Marlin/src/module/ft_motion.cpp | 27 ++++++++++++++++++++-------
 3 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/Marlin/src/inc/SanityCheck.h b/Marlin/src/inc/SanityCheck.h
index 5856723c77..148f1f8292 100644
--- a/Marlin/src/inc/SanityCheck.h
+++ b/Marlin/src/inc/SanityCheck.h
@@ -4495,9 +4495,7 @@ static_assert(_PLUS_TEST(3), "DEFAULT_MAX_ACCELERATION values must be positive."
     #error "EMERGENCY_PARSER is required with FTM_RESONANCE_TEST (to cancel the test)."
   #endif
   #if !HAS_STANDARD_MOTION
-    #if ENABLED(NONLINEAR_EXTRUSION)
-      #error "NONLINEAR_EXTRUSION is not yet available in FT_MOTION. Disable NO_STANDARD_MOTION if you require it."
-    #elif ENABLED(SMOOTH_LIN_ADVANCE)
+    #if ENABLED(SMOOTH_LIN_ADVANCE)
       #error "SMOOTH_LIN_ADVANCE is not yet available in FT_MOTION. Disable NO_STANDARD_MOTION if you require it."
     #elif ENABLED(MIXING_EXTRUDER)
       #error "MIXING_EXTRUDER is not yet available in FT_MOTION. Disable NO_STANDARD_MOTION if you require it."
diff --git a/Marlin/src/inc/Warnings.cpp b/Marlin/src/inc/Warnings.cpp
index 9c4eabaf6e..09266b90b7 100644
--- a/Marlin/src/inc/Warnings.cpp
+++ b/Marlin/src/inc/Warnings.cpp
@@ -941,9 +941,6 @@
   #if ENABLED(I2S_STEPPER_STREAM)
     #warning "FT_MOTION has not been tested with I2S_STEPPER_STREAM."
   #endif
-  #if ENABLED(NONLINEAR_EXTRUSION)
-    #warning "NONLINEAR_EXTRUSION does not (currently) operate when FT_MOTION is the active motion system."
-  #endif
   #if ENABLED(LIN_ADVANCE)
     #warning "Be aware that FT_MOTION K factor is now set with M900 K (same as LIN_ADVANCE)."
     #if DISABLED(FTM_SMOOTHING)
diff --git a/Marlin/src/module/ft_motion.cpp b/Marlin/src/module/ft_motion.cpp
index f6113c398e..7cf5b5ac7f 100644
--- a/Marlin/src/module/ft_motion.cpp
+++ b/Marlin/src/module/ft_motion.cpp
@@ -467,13 +467,26 @@ xyze_float_t FTMotion::calc_traj_point(const float dist) {
 
   #if FTM_HAS_LIN_ADVANCE
     const float advK = planner.get_advance_k();
-    if (advK) {
-      const float traj_e = traj_coords.e;
-      if (use_advance_lead) {
-        // Don't apply LA to retract/unretract blocks
-        const float e_rate = (traj_e - prev_traj_e) * (FTM_FS);
-        traj_coords.e += e_rate * advK;
-      }
+    // Apply LA/NLE only to printing (not retract/unretract) blocks
+    if (use_advance_lead && (advK TERN(NONLINEAR_EXTRUSION, || stepper.ne.settings.enabled,))) {
+      TERN(NONLINEAR_EXTRUSION,, const) float traj_e = traj_coords.e;
+      const float traj_e_delta = traj_e - prev_traj_e; // extruder delta in mm
+      const float e_rate = traj_e_delta * FTM_FS;      // extruder velocity in mm/s
+
+      traj_coords.e += e_rate * advK;
+
+      #if ENABLED(NONLINEAR_EXTRUSION)
+        if (stepper.ne.settings.enabled) {
+          const float multiplier = max(stepper.ne.settings.coeff.C, stepper.ne.settings.coeff.A * sq(e_rate) + stepper.ne.settings.coeff.B * e_rate + stepper.ne.settings.coeff.C);
+          const float nle_term = traj_e_delta * (multiplier - 1);
+
+          traj_coords.e += nle_term;
+          traj_e += nle_term;
+          startPos.e += nle_term;
+          endPos_prevBlock.e += nle_term;
+        }
+      #endif
+
       prev_traj_e = traj_e;
     }
   #endif