Gpencil: Time Offset modifier new Chain mode

This patch adds 5th mode to Time offset modifier, which should allow 
to create time segments list.

This will allow users to chain together multiple time ranges in 4 modes:

- Forward
- Backwards
- Pingpong
- Reverse  Pingpong

It also comes with additional Repeat parameter which specifies number 
of times particular segment should run.

The mechanic of it is transforming initial parameters into array of frames which 
are mapped to existing cfra (current frame) value.
Prototype : https://jsfiddle.net/ha2sjw8p/3/

This is also closely aligned to community request: 
https://blender.community/c/rightclickselect/Txhbbc/

This should allow creation of complex animations like dancing, 
which consists of repeating loops and transitions to the next.
One important side effect of this is dramatically reduced 
file sizes, as user no longer needs to copy paste keyframes.

Reviewed By: antoniov, mendio, pepeland

Differential Revision: https://developer.blender.org/D15052

1 files changed, 122 insertions, 1 deletions

diff --git a/source/blender/makesrna/intern/rna_gpencil_modifier.c b/source/blender/makesrna/intern/rna_gpencil_modifier.c
index 0a400d3bcef..ae8208ed0d8 100644
--- a/source/blender/makesrna/intern/rna_gpencil_modifier.c
+++ b/source/blender/makesrna/intern/rna_gpencil_modifier.c
@@ -201,7 +201,19 @@ static const EnumPropertyItem rna_enum_time_mode_items[] = {
     {GP_TIME_MODE_NORMAL, "NORMAL", 0, "Regular", "Apply offset in usual animation direction"},
     {GP_TIME_MODE_REVERSE, "REVERSE", 0, "Reverse", "Apply offset in reverse animation direction"},
     {GP_TIME_MODE_FIX, "FIX", 0, "Fixed Frame", "Keep frame and do not change with time"},
-    {GP_TIME_MODE_PINGPONG, "PINGPONG", 0, "Ping Pong", "Loop back and forth"},
+    {GP_TIME_MODE_PINGPONG, "PINGPONG", 0, "Ping Pong", "Loop back and forth starting in reverse"},
+    {GP_TIME_MODE_CHAIN, "CHAIN", 0, "Chain", "List of chained animation segments"},
+    {0, NULL, 0, NULL, NULL},
+};
+
+static const EnumPropertyItem rna_enum_time_seg_mode_items[] = {
+    {GP_TIME_SEG_MODE_NORMAL, "NORMAL", 0, "Regular", "Apply offset in usual animation direction"},
+    {GP_TIME_SEG_MODE_REVERSE,
+     "REVERSE",
+     0,
+     "Reverse",
+     "Apply offset in reverse animation direction"},
+    {GP_TIME_SEG_MODE_PINGPONG, "PINGPONG", 0, "Ping Pong", "Loop back and forth"},
     {0, NULL, 0, NULL, NULL},
 };
 
@@ -791,7 +803,32 @@ static void rna_GpencilDash_segments_begin(CollectionPropertyIterator *iter, Poi
       iter, dmd->segments, sizeof(DashGpencilModifierSegment), dmd->segments_len, false, NULL);
 }
 
+static void rna_GpencilTime_segments_begin(CollectionPropertyIterator *iter, PointerRNA *ptr)
+{
+  TimeGpencilModifierData *gpmd = (TimeGpencilModifierData *)ptr->data;
+  rna_iterator_array_begin(
+      iter, gpmd->segments, sizeof(TimeGpencilModifierSegment), gpmd->segments_len, false, NULL);
+}
+
+static char *rna_TimeGpencilModifierSegment_path(const PointerRNA *ptr)
+{
+  TimeGpencilModifierSegment *ds = (TimeGpencilModifierSegment *)ptr->data;
+
+  TimeGpencilModifierData *gpmd = (TimeGpencilModifierData *)ds->gpmd;
+
+  BLI_assert(gpmd != NULL);
+
+  char name_esc[sizeof(gpmd->modifier.name) * 2];
+  BLI_str_escape(name_esc, gpmd->modifier.name, sizeof(name_esc));
+
+  char ds_name_esc[sizeof(ds->name) * 2];
+  BLI_str_escape(ds_name_esc, ds->name, sizeof(ds_name_esc));
+
+  return BLI_sprintfN("grease_pencil_modifiers[\"%s\"].segments[\"%s\"]", name_esc, ds_name_esc);
+}
+
 static char *rna_DashGpencilModifierSegment_path(const PointerRNA *ptr)
+
 {
   const DashGpencilModifierSegment *ds = (DashGpencilModifierSegment *)ptr->data;
 
@@ -819,6 +856,17 @@ static bool dash_segment_name_exists_fn(void *arg, const char *name)
   return false;
 }
 
+static bool time_segment_name_exists_fn(void *arg, const char *name)
+{
+  const TimeGpencilModifierData *gpmd = (const TimeGpencilModifierData *)arg;
+  for (int i = 0; i < gpmd->segments_len; i++) {
+    if (STREQ(gpmd->segments[i].name, name) && gpmd->segments[i].name != name) {
+      return true;
+    }
+  }
+  return false;
+}
+
 static void rna_DashGpencilModifierSegment_name_set(PointerRNA *ptr, const char *value)
 {
   DashGpencilModifierSegment *ds = ptr->data;
@@ -842,6 +890,29 @@ static void rna_DashGpencilModifierSegment_name_set(PointerRNA *ptr, const char
   BKE_animdata_fix_paths_rename_all(NULL, prefix, oldname, ds->name);
 }
 
+static void rna_TimeGpencilModifierSegment_name_set(PointerRNA *ptr, const char *value)
+{
+  TimeGpencilModifierSegment *ds = ptr->data;
+
+  char oldname[sizeof(ds->name)];
+  BLI_strncpy(oldname, ds->name, sizeof(ds->name));
+
+  BLI_strncpy_utf8(ds->name, value, sizeof(ds->name));
+
+  BLI_assert(ds->gpmd != NULL);
+  BLI_uniquename_cb(
+      time_segment_name_exists_fn, ds->gpmd, "Segment", '.', ds->name, sizeof(ds->name));
+
+  char name_esc[sizeof(ds->gpmd->modifier.name) * 2];
+  BLI_str_escape(name_esc, ds->gpmd->modifier.name, sizeof(name_esc));
+
+  char prefix[36 + sizeof(name_esc) + 1];
+  SNPRINTF(prefix, "grease_pencil_modifiers[\"%s\"].segments", name_esc);
+
+  /* Fix all the animation data which may link to this. */
+  BKE_animdata_fix_paths_rename_all(NULL, prefix, oldname, ds->name);
+}
+
 static int rna_ShrinkwrapGpencilModifier_face_cull_get(PointerRNA *ptr)
 {
   ShrinkwrapGpencilModifierData *swm = (ShrinkwrapGpencilModifierData *)ptr->data;
@@ -1718,6 +1789,38 @@ static void rna_def_modifier_gpenciltime(BlenderRNA *brna)
 {
   StructRNA *srna;
   PropertyRNA *prop;
+  srna = RNA_def_struct(brna, "TimeGpencilModifierSegment", NULL);
+  RNA_def_struct_ui_text(srna, "Time Modifier Segment", "Configuration for a single dash segment");
+  RNA_def_struct_sdna(srna, "TimeGpencilModifierSegment");
+  RNA_def_struct_path_func(srna, "rna_TimeGpencilModifierSegment_path");
+
+  prop = RNA_def_property(srna, "name", PROP_STRING, PROP_NONE);
+  RNA_def_property_ui_text(prop, "Name", "Name of the dash segment");
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
+  RNA_def_property_string_funcs(prop, NULL, NULL, "rna_TimeGpencilModifierSegment_name_set");
+  RNA_def_property_update(prop, NC_OBJECT | ND_MODIFIER | NA_RENAME, NULL);
+  RNA_def_struct_name_property(srna, prop);
+
+  prop = RNA_def_property(srna, "seg_start", PROP_INT, PROP_NONE);
+  RNA_def_property_range(prop, 0, INT16_MAX);
+  RNA_def_property_ui_text(prop, "Frame Start", "First frame of the segment");
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
+
+  prop = RNA_def_property(srna, "seg_end", PROP_INT, PROP_NONE);
+  RNA_def_property_range(prop, 0, INT16_MAX);
+  RNA_def_property_ui_text(prop, "End", "Last frame of the segment");
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
+
+  prop = RNA_def_property(srna, "seg_repeat", PROP_INT, PROP_NONE);
+  RNA_def_property_range(prop, 0, INT16_MAX);
+  RNA_def_property_ui_text(prop, "Repeat", "Number of cycle repeats");
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
+
+  prop = RNA_def_property(srna, "seg_mode", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_sdna(prop, NULL, "seg_mode");
+  RNA_def_property_enum_items(prop, rna_enum_time_seg_mode_items);
+  RNA_def_property_ui_text(prop, "Mode", "");
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
 
   srna = RNA_def_struct(brna, "TimeGpencilModifier", "GpencilModifier");
   RNA_def_struct_ui_text(srna, "Time Offset Modifier", "Time offset modifier");
@@ -1726,6 +1829,24 @@ static void rna_def_modifier_gpenciltime(BlenderRNA *brna)
 
   RNA_define_lib_overridable(true);
 
+  prop = RNA_def_property(srna, "segments", PROP_COLLECTION, PROP_NONE);
+  RNA_def_property_struct_type(prop, "TimeGpencilModifierSegment");
+  RNA_def_property_collection_sdna(prop, NULL, "segments", NULL);
+  RNA_def_property_collection_funcs(prop,
+                                    "rna_GpencilTime_segments_begin",
+                                    "rna_iterator_array_next",
+                                    "rna_iterator_array_end",
+                                    "rna_iterator_array_get",
+                                    NULL,
+                                    NULL,
+                                    NULL,
+                                    NULL);
+  RNA_def_property_ui_text(prop, "Segments", "");
+
+  prop = RNA_def_property(srna, "segment_active_index", PROP_INT, PROP_UNSIGNED);
+  RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+  RNA_def_property_ui_text(prop, "Active Dash Segment Index", "Active index in the segment list");
+
   prop = RNA_def_property(srna, "mode", PROP_ENUM, PROP_NONE);
   RNA_def_property_enum_sdna(prop, NULL, "mode");
   RNA_def_property_enum_items(prop, rna_enum_time_mode_items);