[Bf-blender-cvs] [50919413fe7] master: NLA: Fix strip Sync Length moving animation data

[Wayde Moss]

Commit: 50919413fe7b3fd3e3cbf189e42a48936984b9ce
Author: Wayde Moss
Date:   Thu Aug 20 16:22:44 2020 +0200
Branches: master
https://developer.blender.org/rB50919413fe7b3fd3e3cbf189e42a48936984b9ce

NLA: Fix strip Sync Length moving animation data

Change the way Sync Length works so that it keeps keyframes at the same
key as before the sync. Now when the user exits tweak mode, the overall
NLA result is unchanged.

Reviewed By: sybren

Differential Revision: https://developer.blender.org/D7602

===================================================================

M	source/blender/blenkernel/BKE_nla.h
M	source/blender/blenkernel/intern/nla.c
M	source/blender/editors/space_nla/nla_edit.c

===================================================================

diff --git a/source/blender/blenkernel/BKE_nla.h b/source/blender/blenkernel/BKE_nla.h
index 8b3231e5302..06e9e58d6d7 100644
--- a/source/blender/blenkernel/BKE_nla.h
+++ b/source/blender/blenkernel/BKE_nla.h
@@ -102,6 +102,7 @@ void BKE_nlastrip_set_active(struct AnimData *adt, struct NlaStrip *strip);
 
 bool BKE_nlastrip_within_bounds(struct NlaStrip *strip, float min, float max);
 void BKE_nlastrip_recalculate_bounds(struct NlaStrip *strip);
+void BKE_nlastrip_recalculate_bounds_sync_action(struct NlaStrip *strip);
 
 void BKE_nlastrip_validate_name(struct AnimData *adt, struct NlaStrip *strip);
 
diff --git a/source/blender/blenkernel/intern/nla.c b/source/blender/blenkernel/intern/nla.c
index 1ba82b352d1..e5527ed987a 100644
--- a/source/blender/blenkernel/intern/nla.c
+++ b/source/blender/blenkernel/intern/nla.c
@@ -1361,6 +1361,25 @@ static void nlastrip_fix_resize_overlaps(NlaStrip *strip)
   }
 }
 
+/** Recalculate the start and end frames for the strip to match the bounds of its action such that
+ * the overall NLA animation result is unchanged. */
+void BKE_nlastrip_recalculate_bounds_sync_action(NlaStrip *strip)
+{
+  float prev_actstart;
+
+  if (strip == NULL || strip->type != NLASTRIP_TYPE_CLIP) {
+    return;
+  }
+
+  prev_actstart = strip->actstart;
+
+  calc_action_range(strip->act, &strip->actstart, &strip->actend, 0);
+
+  /* Set start such that key's do not visually move, to preserve the overall animation result. */
+  strip->start += (strip->actstart - prev_actstart) * strip->scale;
+
+  BKE_nlastrip_recalculate_bounds(strip);
+}
 /* Recalculate the start and end frames for the current strip, after changing
  * the extents of the action or the mapping (repeats or scale factor) info
  */
@@ -2133,11 +2152,7 @@ void BKE_nla_tweakmode_exit(AnimData *adt)
 
     /* must be action-clip only (transitions don't have scale) */
     if ((strip->type == NLASTRIP_TYPE_CLIP) && (strip->act)) {
-      /* recalculate the length of the action */
-      calc_action_range(strip->act, &strip->actstart, &strip->actend, 0);
-
-      /* adjust the strip extents in response to this */
-      BKE_nlastrip_recalculate_bounds(strip);
+      BKE_nlastrip_recalculate_bounds_sync_action(strip);
     }
   }
 
@@ -2151,11 +2166,7 @@ void BKE_nla_tweakmode_exit(AnimData *adt)
       /* sync strip extents if this strip uses the same action */
       if ((adt->actstrip) && (adt->actstrip->act == strip->act) &&
           (strip->flag & NLASTRIP_FLAG_SYNC_LENGTH)) {
-        /* recalculate the length of the action */
-        calc_action_range(strip->act, &strip->actstart, &strip->actend, 0);
-
-        /* adjust the strip extents in response to this */
-        BKE_nlastrip_recalculate_bounds(strip);
+        BKE_nlastrip_recalculate_bounds_sync_action(strip);
       }
 
       /* clear tweakuser flag */
diff --git a/source/blender/editors/space_nla/nla_edit.c b/source/blender/editors/space_nla/nla_edit.c
index bc9bd0e18f2..dc8f616c5e6 100644
--- a/source/blender/editors/space_nla/nla_edit.c
+++ b/source/blender/editors/space_nla/nla_edit.c
@@ -1847,11 +1847,7 @@ static int nlaedit_sync_actlen_exec(bContext *C, wmOperator *op)
           continue;
         }
 
-        /* recalculate the length of the action */
-        calc_action_range(strip->act, &strip->actstart, &strip->actend, 0);
-
-        /* adjust the strip extents in response to this */
-        BKE_nlastrip_recalculate_bounds(strip);
+        BKE_nlastrip_recalculate_bounds_sync_action(strip);
 
         ale->update |= ANIM_UPDATE_DEPS;
       }