Animation: add function to blend Action into pose

Add function `BKE_pose_apply_action_blend()`, which blends a given
Action into current pose. The Action is evaluated at a specified frame,
and the result is applied to the armature's pose.

A blend factor can be given to blend between the current pose and the
one in the Action. Quaternions are interpolated with SLERP; it is
assumed that their FCurves are consecutively stored in the Action.

This function will be used in the upcoming new Pose Library.

1 files changed, 4 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_armature.h b/source/blender/blenkernel/BKE_armature.h
index a09c3e361b6..1f9e304c7a3 100644
--- a/source/blender/blenkernel/BKE_armature.h
+++ b/source/blender/blenkernel/BKE_armature.h
@@ -215,6 +215,10 @@ void BKE_pose_apply_action_all_bones(struct Object *ob,
                                      struct bAction *action,
                                      struct AnimationEvalContext *anim_eval_context);
 
+void BKE_pose_apply_action_blend(struct Object *ob,
+                                 struct bAction *action,
+                                 struct AnimationEvalContext *anim_eval_context,
+                                 float blend_factor);
 
 void vec_roll_to_mat3(const float vec[3], const float roll, float r_mat[3][3]);
 void vec_roll_to_mat3_normalized(const float nor[3], const float roll, float r_mat[3][3]);