From 10e23fd1046a0fd1f2e2f7cac7fc897cc0ea99be Mon Sep 17 00:00:00 2001
From: Wayde Moss <GuiltyGhost>
Date: Fri, 5 Feb 2021 16:45:34 -0500
Subject: NLA: Refactor Transition, Use Snapshot Blend Func

The function `nlastrip_evaluate_transition()` has been slightly
modified to use `nlasnapshot_blend()` instead of it's own special
blending function `nlaeval_snapshot_mix_and_free()`.

No user functional changes

Reviewed By: sybren, #animation_rigging

Differential Revision: https://developer.blender.org/D10221
---
 source/blender/blenkernel/intern/anim_sys.c | 65 +++++++----------------------
 1 file changed, 14 insertions(+), 51 deletions(-)

(limited to 'source/blender/blenkernel/intern')

diff --git a/source/blender/blenkernel/intern/anim_sys.c b/source/blender/blenkernel/intern/anim_sys.c
index 19684cbc788..da4c43e12a4 100644
--- a/source/blender/blenkernel/intern/anim_sys.c
+++ b/source/blender/blenkernel/intern/anim_sys.c
@@ -1657,55 +1657,6 @@ static bool nla_combine_quaternion_get_inverted_strip_values(const float lower_v
   return true;
 }
 
-/* Blend the specified snapshots into the target, and free the input snapshots. */
-static void nlaeval_snapshot_mix_and_free(NlaEvalData *nlaeval,
-                                          NlaEvalSnapshot *out,
-                                          NlaEvalSnapshot *in1,
-                                          NlaEvalSnapshot *in2,
-                                          float alpha)
-{
-  BLI_assert(in1->base == out && in2->base == out);
-
-  nlaeval_snapshot_ensure_size(out, nlaeval->num_channels);
-
-  for (int i = 0; i < nlaeval->num_channels; i++) {
-    NlaEvalChannelSnapshot *c_in1 = nlaeval_snapshot_get(in1, i);
-    NlaEvalChannelSnapshot *c_in2 = nlaeval_snapshot_get(in2, i);
-
-    if (c_in1 || c_in2) {
-      NlaEvalChannelSnapshot *c_out = out->channels[i];
-
-      /* Steal the entry from one of the input snapshots. */
-      if (c_out == NULL) {
-        if (c_in1 != NULL) {
-          c_out = c_in1;
-          in1->channels[i] = NULL;
-        }
-        else {
-          c_out = c_in2;
-          in2->channels[i] = NULL;
-        }
-      }
-
-      if (c_in1 == NULL) {
-        c_in1 = nlaeval_snapshot_find_channel(in1->base, c_out->channel);
-      }
-      if (c_in2 == NULL) {
-        c_in2 = nlaeval_snapshot_find_channel(in2->base, c_out->channel);
-      }
-
-      out->channels[i] = c_out;
-
-      for (int j = 0; j < c_out->length; j++) {
-        c_out->values[j] = c_in1->values[j] * (1.0f - alpha) + c_in2->values[j] * alpha;
-      }
-    }
-  }
-
-  nlaeval_snapshot_free_data(in1);
-  nlaeval_snapshot_free_data(in2);
-}
-
 /* ---------------------- */
 /* F-Modifier stack joining/separation utilities -
  * should we generalize these for BLI_listbase.h interface? */
@@ -1910,8 +1861,13 @@ static void nlastrip_evaluate_transition(PointerRNA *ptr,
   nlastrip_evaluate(
       ptr, channels, &tmp_modifiers, &tmp_nes, &snapshot2, anim_eval_context, flush_to_original);
 
-  /* accumulate temp-buffer and full-buffer, using the 'real' strip */
-  nlaeval_snapshot_mix_and_free(channels, snapshot, &snapshot1, &snapshot2, nes->strip_time);
+  /** Replace \a snapshot2 NULL channels with base or default values so all channels blend. */
+  nlasnapshot_ensure_channels(channels, &snapshot2);
+  nlasnapshot_blend(
+      channels, &snapshot1, &snapshot2, NLASTRIP_MODE_REPLACE, nes->strip_time, snapshot);
+
+  nlaeval_snapshot_free_data(&snapshot1);
+  nlaeval_snapshot_free_data(&snapshot2);
 
   /* unlink this strip's modifiers from the parent's modifiers again */
   nlaeval_fmodifiers_split_stacks(&nes->strip->modifiers, modifiers);
@@ -2515,6 +2471,13 @@ static void animsys_calculate_nla(PointerRNA *ptr,
 
 /* ---------------------- */
 
+void nlasnapshot_ensure_channels(NlaEvalData *eval_data, NlaEvalSnapshot *snapshot)
+{
+  LISTBASE_FOREACH (NlaEvalChannel *, nec, &eval_data->channels) {
+    nlaeval_snapshot_ensure_channel(snapshot, nec);
+  }
+}
+
 /** Blends the \a lower_snapshot with the \a upper_snapshot into \a r_blended_snapshot according
  * to the given \a upper_blendmode and \a upper_influence. */
 void nlasnapshot_blend(NlaEvalData *eval_data,
-- 
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