Cleanup: improve naming and comments of scene frame/ctime functions

Confusingly, BKE_scene_frame_get did not match the frame number as expected by
BKE_scene_frame_set. Instead it return the value after time remapping, which
is commonly named "ctime".

* Rename BKE_scene_frame_get to BKE_scene_ctime_get
* Add a new BKE_scene_frame_get that matches BKE_scene_frame_set
* Use int/float depending if fractional frame is expected

9 files changed, 48 insertions, 45 deletions

diff --git a/source/blender/blenkernel/intern/armature.c b/source/blender/blenkernel/intern/armature.c
index 22d6cfba893..b8ed519e8d1 100644
--- a/source/blender/blenkernel/intern/armature.c
+++ b/source/blender/blenkernel/intern/armature.c
@@ -2843,7 +2843,7 @@ void BKE_pose_where_is(struct Depsgraph *depsgraph, Scene *scene, Object *ob)
    * hopefully this is OK. */
   BKE_pose_ensure(NULL, ob, arm, true);
 
-  ctime = BKE_scene_frame_get(scene); /* not accurate... */
+  ctime = BKE_scene_ctime_get(scene); /* not accurate... */
 
   /* In edit-mode or rest-position we read the data from the bones. */
   if (arm->edbo || (arm->flag & ARM_RESTPOS)) {
diff --git a/source/blender/blenkernel/intern/armature_update.c b/source/blender/blenkernel/intern/armature_update.c
index 0a195f2ba55..35ae2d2dbef 100644
--- a/source/blender/blenkernel/intern/armature_update.c
+++ b/source/blender/blenkernel/intern/armature_update.c
@@ -828,7 +828,7 @@ void BKE_pose_eval_init_ik(struct Depsgraph *depsgraph, Scene *scene, Object *ob
 {
   DEG_debug_print_eval(depsgraph, __func__, object->id.name, object);
   BLI_assert(object->type == OB_ARMATURE);
-  const float ctime = BKE_scene_frame_get(scene); /* not accurate... */
+  const float ctime = BKE_scene_ctime_get(scene); /* not accurate... */
   bArmature *armature = (bArmature *)object->data;
   if (armature->flag & ARM_RESTPOS) {
     return;
@@ -869,7 +869,7 @@ void BKE_pose_eval_bone(struct Depsgraph *depsgraph, Scene *scene, Object *objec
       else {
         if ((pchan->flag & POSE_DONE) == 0) {
           /* TODO(sergey): Use time source node for time. */
-          float ctime = BKE_scene_frame_get(scene); /* not accurate... */
+          float ctime = BKE_scene_ctime_get(scene); /* not accurate... */
           BKE_pose_where_is_bone(depsgraph, scene, object, pchan, ctime, 1);
         }
       }
@@ -897,7 +897,7 @@ void BKE_pose_constraints_evaluate(struct Depsgraph *depsgraph,
   }
   else {
     if ((pchan->flag & POSE_DONE) == 0) {
-      float ctime = BKE_scene_frame_get(scene); /* not accurate... */
+      float ctime = BKE_scene_ctime_get(scene); /* not accurate... */
       BKE_pose_where_is_bone(depsgraph, scene, object, pchan, ctime, 1);
     }
   }
@@ -981,7 +981,7 @@ void BKE_pose_iktree_evaluate(struct Depsgraph *depsgraph,
   DEG_debug_print_eval_subdata(
       depsgraph, __func__, object->id.name, object, "rootchan", rootchan->name, rootchan);
   BLI_assert(object->type == OB_ARMATURE);
-  const float ctime = BKE_scene_frame_get(scene); /* not accurate... */
+  const float ctime = BKE_scene_ctime_get(scene); /* not accurate... */
   if (armature->flag & ARM_RESTPOS) {
     return;
   }
@@ -1002,7 +1002,7 @@ void BKE_pose_splineik_evaluate(struct Depsgraph *depsgraph,
   DEG_debug_print_eval_subdata(
       depsgraph, __func__, object->id.name, object, "rootchan", rootchan->name, rootchan);
   BLI_assert(object->type == OB_ARMATURE);
-  const float ctime = BKE_scene_frame_get(scene); /* not accurate... */
+  const float ctime = BKE_scene_ctime_get(scene); /* not accurate... */
   if (armature->flag & ARM_RESTPOS) {
     return;
   }
@@ -1031,7 +1031,7 @@ void BKE_pose_eval_cleanup(struct Depsgraph *depsgraph, Scene *scene, Object *ob
   bPose *pose = object->pose;
   BLI_assert(pose != NULL);
   UNUSED_VARS_NDEBUG(pose);
-  const float ctime = BKE_scene_frame_get(scene); /* not accurate... */
+  const float ctime = BKE_scene_ctime_get(scene); /* not accurate... */
   DEG_debug_print_eval(depsgraph, __func__, object->id.name, object);
   BLI_assert(object->type == OB_ARMATURE);
   /* Release the IK tree. */
diff --git a/source/blender/blenkernel/intern/cachefile.c b/source/blender/blenkernel/intern/cachefile.c
index 30e9ae39b67..eaba5d33a20 100644
--- a/source/blender/blenkernel/intern/cachefile.c
+++ b/source/blender/blenkernel/intern/cachefile.c
@@ -314,7 +314,7 @@ bool BKE_cachefile_filepath_get(const Main *bmain,
 
   if (cache_file->is_sequence && BLI_path_frame_get(r_filepath, &fframe, &frame_len)) {
     Scene *scene = DEG_get_evaluated_scene(depsgraph);
-    const float ctime = BKE_scene_frame_get(scene);
+    const float ctime = BKE_scene_ctime_get(scene);
     const float fps = (((double)scene->r.frs_sec) / (double)scene->r.frs_sec_base);
     const float frame = BKE_cachefile_time_offset(cache_file, ctime, fps);
 
diff --git a/source/blender/blenkernel/intern/dynamicpaint.c b/source/blender/blenkernel/intern/dynamicpaint.c
index 6091e774d4a..52996e3bcc7 100644
--- a/source/blender/blenkernel/intern/dynamicpaint.c
+++ b/source/blender/blenkernel/intern/dynamicpaint.c
@@ -3818,7 +3818,7 @@ static void dynamicPaint_brushMeshCalculateVelocity(Depsgraph *depsgraph,
                                       ob,
                                       true,
                                       SUBFRAME_RECURSION,
-                                      BKE_scene_frame_get(scene),
+                                      BKE_scene_ctime_get(scene),
                                       eModifierType_DynamicPaint);
   mesh_p = BKE_mesh_copy_for_eval(dynamicPaint_brush_mesh_get(brush), false);
   numOfVerts_p = mesh_p->totvert;
@@ -3834,7 +3834,7 @@ static void dynamicPaint_brushMeshCalculateVelocity(Depsgraph *depsgraph,
                                       ob,
                                       true,
                                       SUBFRAME_RECURSION,
-                                      BKE_scene_frame_get(scene),
+                                      BKE_scene_ctime_get(scene),
                                       eModifierType_DynamicPaint);
   mesh_c = dynamicPaint_brush_mesh_get(brush);
   numOfVerts_c = mesh_c->totvert;
@@ -3894,7 +3894,7 @@ static void dynamicPaint_brushObjectCalculateVelocity(
                                       ob,
                                       false,
                                       SUBFRAME_RECURSION,
-                                      BKE_scene_frame_get(scene),
+                                      BKE_scene_ctime_get(scene),
                                       eModifierType_DynamicPaint);
   copy_m4_m4(prev_obmat, ob->obmat);
 
@@ -3906,7 +3906,7 @@ static void dynamicPaint_brushObjectCalculateVelocity(
                                       ob,
                                       false,
                                       SUBFRAME_RECURSION,
-                                      BKE_scene_frame_get(scene),
+                                      BKE_scene_ctime_get(scene),
                                       eModifierType_DynamicPaint);
 
   /* calculate speed */
@@ -6271,7 +6271,7 @@ static int dynamicPaint_doStep(Depsgraph *depsgraph,
                                                 brushObj,
                                                 true,
                                                 SUBFRAME_RECURSION,
-                                                BKE_scene_frame_get(scene),
+                                                BKE_scene_ctime_get(scene),
                                                 eModifierType_DynamicPaint);
           }
 
@@ -6312,7 +6312,7 @@ static int dynamicPaint_doStep(Depsgraph *depsgraph,
                                                 brushObj,
                                                 true,
                                                 SUBFRAME_RECURSION,
-                                                BKE_scene_frame_get(scene),
+                                                BKE_scene_ctime_get(scene),
                                                 eModifierType_DynamicPaint);
           }
 
diff --git a/source/blender/blenkernel/intern/fluid.c b/source/blender/blenkernel/intern/fluid.c
index 947417af55d..2b48683a3a8 100644
--- a/source/blender/blenkernel/intern/fluid.c
+++ b/source/blender/blenkernel/intern/fluid.c
@@ -1283,10 +1283,10 @@ static void compute_obstaclesemission(Scene *scene,
 #  endif
         /* Update frame time, this is considering current subframe fraction
          * BLI_mutex_lock() called in manta_step(), so safe to update subframe here
-         * TODO(sebbas): Using BKE_scene_frame_get(scene) instead of new DEG_get_ctime(depsgraph)
+         * TODO(sebbas): Using BKE_scene_ctime_get(scene) instead of new DEG_get_ctime(depsgraph)
          * as subframes don't work with the latter yet. */
         BKE_object_modifier_update_subframe(
-            depsgraph, scene, effecobj, true, 5, BKE_scene_frame_get(scene), eModifierType_Fluid);
+            depsgraph, scene, effecobj, true, 5, BKE_scene_ctime_get(scene), eModifierType_Fluid);
 
         if (subframes) {
           obstacles_from_mesh(effecobj, fds, fes, &bb_temp, subframe_dt);
@@ -1616,7 +1616,7 @@ static void emit_from_particles(Object *flow_ob,
       }
 
       /* `DEG_get_ctime(depsgraph)` does not give sub-frame time. */
-      state.time = BKE_scene_frame_get(scene);
+      state.time = BKE_scene_ctime_get(scene);
 
       if (psys_get_particle_state(&sim, p, &state, 0) == 0) {
         continue;
@@ -2820,10 +2820,10 @@ static void compute_flowsemission(Scene *scene,
 #  endif
         /* Update frame time, this is considering current subframe fraction
          * BLI_mutex_lock() called in manta_step(), so safe to update subframe here
-         * TODO(sebbas): Using BKE_scene_frame_get(scene) instead of new DEG_get_ctime(depsgraph)
+         * TODO(sebbas): Using BKE_scene_ctime_get(scene) instead of new DEG_get_ctime(depsgraph)
          * as subframes don't work with the latter yet. */
         BKE_object_modifier_update_subframe(
-            depsgraph, scene, flowobj, true, 5, BKE_scene_frame_get(scene), eModifierType_Fluid);
+            depsgraph, scene, flowobj, true, 5, BKE_scene_ctime_get(scene), eModifierType_Fluid);
 
         /* Emission from particles. */
         if (ffs->source == FLUID_FLOW_SOURCE_PARTICLES) {
diff --git a/source/blender/blenkernel/intern/object_update.c b/source/blender/blenkernel/intern/object_update.c
index ab247ef5507..7e15ac5de5d 100644
--- a/source/blender/blenkernel/intern/object_update.c
+++ b/source/blender/blenkernel/intern/object_update.c
@@ -123,7 +123,7 @@ void BKE_object_eval_parent(Depsgraph *depsgraph, Object *ob)
 void BKE_object_eval_constraints(Depsgraph *depsgraph, Scene *scene, Object *ob)
 {
   bConstraintOb *cob;
-  float ctime = BKE_scene_frame_get(scene);
+  float ctime = BKE_scene_ctime_get(scene);
 
   DEG_debug_print_eval(depsgraph, __func__, ob->id.name, ob);
 
diff --git a/source/blender/blenkernel/intern/particle.c b/source/blender/blenkernel/intern/particle.c
index 7504fbeed19..db1fbb56125 100644
--- a/source/blender/blenkernel/intern/particle.c
+++ b/source/blender/blenkernel/intern/particle.c
@@ -3961,7 +3961,7 @@ static ModifierData *object_add_or_copy_particle_system(
   psys->totpart = 0;
   psys->flag = PSYS_CURRENT;
   if (scene != NULL) {
-    psys->cfra = BKE_scene_frame_to_ctime(scene, CFRA + 1);
+    psys->cfra = BKE_scene_frame_to_ctime(scene, scene->r.cfra + 1);
   }
 
   DEG_relations_tag_update(bmain);
diff --git a/source/blender/blenkernel/intern/pointcache.c b/source/blender/blenkernel/intern/pointcache.c
index 90018e64f78..9ed5b0230e6 100644
--- a/source/blender/blenkernel/intern/pointcache.c
+++ b/source/blender/blenkernel/intern/pointcache.c
@@ -2807,8 +2807,8 @@ void BKE_ptcache_id_time(
   cache = pid->cache;
 
   if (timescale) {
-    time = BKE_scene_frame_get(scene);
-    nexttime = BKE_scene_frame_to_ctime(scene, CFRA + 1.0f);
+    time = BKE_scene_ctime_get(scene);
+    nexttime = BKE_scene_frame_to_ctime(scene, scene->r.cfra + 1);
 
     *timescale = MAX2(nexttime - time, 0.0f);
   }
diff --git a/source/blender/blenkernel/intern/scene.c b/source/blender/blenkernel/intern/scene.c
index f8f4d52fcf2..e47720f9bcd 100644
--- a/source/blender/blenkernel/intern/scene.c
+++ b/source/blender/blenkernel/intern/scene.c
@@ -2299,10 +2299,7 @@ Object *BKE_scene_camera_switch_find(Scene *scene)
     return NULL;
   }
 
-  const int cfra = ((scene->r.images == scene->r.framapto) ?
-                        scene->r.cfra :
-                        (int)(scene->r.cfra *
-                              ((float)scene->r.framapto / (float)scene->r.images)));
+  const int ctime = (int)BKE_scene_ctime_get(scene);
   int frame = -(MAXFRAME + 1);
   int min_frame = MAXFRAME + 1;
   Object *camera = NULL;
@@ -2310,11 +2307,11 @@ Object *BKE_scene_camera_switch_find(Scene *scene)
 
   LISTBASE_FOREACH (TimeMarker *, m, &scene->markers) {
     if (m->camera && (m->camera->restrictflag & OB_RESTRICT_RENDER) == 0) {
-      if ((m->frame <= cfra) && (m->frame > frame)) {
+      if ((m->frame <= ctime) && (m->frame > frame)) {
         camera = m->camera;
         frame = m->frame;
 
-        if (frame == cfra) {
+        if (frame == ctime) {
           break;
         }
       }
@@ -2396,13 +2393,13 @@ const char *BKE_scene_find_last_marker_name(const Scene *scene, int frame)
   return best_marker ? best_marker->name : NULL;
 }
 
-int BKE_scene_frame_snap_by_seconds(Scene *scene, double interval_in_seconds, int cfra)
+int BKE_scene_frame_snap_by_seconds(Scene *scene, double interval_in_seconds, int frame)
 {
   const int fps = round_db_to_int(FPS * interval_in_seconds);
-  const int second_prev = cfra - mod_i(cfra, fps);
+  const int second_prev = frame - mod_i(frame, fps);
   const int second_next = second_prev + fps;
-  const int delta_prev = cfra - second_prev;
-  const int delta_next = second_next - cfra;
+  const int delta_prev = frame - second_prev;
+  const int delta_next = second_next - frame;
   return (delta_prev < delta_next) ? second_prev : second_next;
 }
 
@@ -2444,16 +2441,17 @@ bool BKE_scene_validate_setscene(Main *bmain, Scene *sce)
   return true;
 }
 
-/**
- * This function is needed to cope with fractional frames, needed for motion blur & physics.
- */
-float BKE_scene_frame_get(const Scene *scene)
+/* Return fractional frame number taking into account subframes and time
+ * remapping. This the time value used by animation, modifiers and physics
+ * evaluation. */
+float BKE_scene_ctime_get(const Scene *scene)
 {
   return BKE_scene_frame_to_ctime(scene, scene->r.cfra);
 }
 
-/* This function is used to obtain arbitrary fractional frames */
-float BKE_scene_frame_to_ctime(const Scene *scene, const float frame)
+/* Convert integer frame number to fractional frame number taking into account
+ * subframes and time remapping. */
+float BKE_scene_frame_to_ctime(const Scene *scene, const int frame)
 {
   float ctime = frame;
   ctime += scene->r.subframe;
@@ -2461,13 +2459,18 @@ float BKE_scene_frame_to_ctime(const Scene *scene, const float frame)
 
   return ctime;
 }
-/**
- * Sets the frame int/float components.
- */
-void BKE_scene_frame_set(struct Scene *scene, double cfra)
+
+/* Get current fractional frame based on frame and subframe. */
+float BKE_scene_frame_get(const Scene *scene)
+{
+  return scene->r.cfra + scene->r.subframe;
+}
+
+/* Set current frame and subframe based on a fractional frame. */
+void BKE_scene_frame_set(Scene *scene, float frame)
 {
   double intpart;
-  scene->r.subframe = modf(cfra, &intpart);
+  scene->r.subframe = modf((double)frame, &intpart);
   scene->r.cfra = (int)intpart;
 }
 
@@ -2736,7 +2739,7 @@ void BKE_scene_graph_update_for_newframe_ex(Depsgraph *depsgraph, const bool cle
      * edits from callback are properly taken into account. Doing a time update on those would
      * lose any possible unkeyed changes made by the handler. */
     if (pass == 0) {
-      const float ctime = BKE_scene_frame_get(scene);
+      const float ctime = BKE_scene_ctime_get(scene);
       DEG_evaluate_on_framechange(depsgraph, ctime);
     }
     else {