From b56715de034b38d630387cd6218ebfbdf766f36c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sybren=20A=2E=20St=C3=BCvel?= <sybren@blender.org>
Date: Tue, 1 Oct 2024 15:32:57 +0200
Subject: [PATCH] Anim: Fix bug updating F-Curves for new Curve (object) points

When modifying a Curve object's points, its animation data is updated to
ensure that changes in point index are reflected in the F-Curve data
paths. This already worked fine for pre-existing Curve points, but
didn't happen correctly for points that were newly added since entering
edit mode.
---
 source/blender/editors/curve/editcurve.cc | 26 +++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/source/blender/editors/curve/editcurve.cc b/source/blender/editors/curve/editcurve.cc
index 8aa6f4c38c0..40da834eb2a 100644
--- a/source/blender/editors/curve/editcurve.cc
+++ b/source/blender/editors/curve/editcurve.cc
@@ -963,9 +963,10 @@ static void fcurve_path_rename(const char *orig_rna_path,
       pt_index = 0;
 
       while (a--) {
+        SNPRINTF(rna_path, "splines[%d].bezier_points[%d]", nu_index, pt_index);
+
         keyIndex = getCVKeyIndex(editnurb, bezt);
         if (keyIndex) {
-          SNPRINTF(rna_path, "splines[%d].bezier_points[%d]", nu_index, pt_index);
           SNPRINTF(orig_rna_path,
                    "splines[%d].bezier_points[%d]",
                    keyIndex->nu_index,
@@ -987,6 +988,16 @@ static void fcurve_path_rename(const char *orig_rna_path,
           keyIndex->nu_index = nu_index;
           keyIndex->pt_index = pt_index;
         }
+        else {
+          /* In this case, the bezier point exists. It just hasn't been indexed yet (which seems to
+           * happen on entering edit mode, so points added after that may not have such an index
+           * yet) */
+
+          /* This is a no-op when it comes to the manipulation of F-Curves. It does find the
+           * relevant F-Curves to place them in `processed_fcurves`, which will prevent them from
+           * being deleted later on. */
+          fcurve_path_rename(rna_path, rna_path, orig_curves, processed_fcurves);
+        }
 
         bezt++;
         pt_index++;
@@ -998,9 +1009,10 @@ static void fcurve_path_rename(const char *orig_rna_path,
       pt_index = 0;
 
       while (a--) {
+        SNPRINTF(rna_path, "splines[%d].points[%d]", nu_index, pt_index);
+
         keyIndex = getCVKeyIndex(editnurb, bp);
         if (keyIndex) {
-          SNPRINTF(rna_path, "splines[%d].points[%d]", nu_index, pt_index);
           SNPRINTF(
               orig_rna_path, "splines[%d].points[%d]", keyIndex->nu_index, keyIndex->pt_index);
           fcurve_path_rename(orig_rna_path, rna_path, orig_curves, processed_fcurves);
@@ -1008,6 +1020,16 @@ static void fcurve_path_rename(const char *orig_rna_path,
           keyIndex->nu_index = nu_index;
           keyIndex->pt_index = pt_index;
         }
+        else {
+          /* In this case, the bezier point exists. It just hasn't been indexed yet (which seems to
+           * happen on entering edit mode, so points added after that may not have such an index
+           * yet) */
+
+          /* This is a no-op when it comes to the manipulation of F-Curves. It does find the
+           * relevant F-Curves to place them in `processed_fcurves`, which will prevent them from
+           * being deleted later on. */
+          fcurve_path_rename(rna_path, rna_path, orig_curves, processed_fcurves);
+        }
 
         bp++;
         pt_index++;