GPencil: Show only first frame if current frame is equals or greater than current frame

Previously, the first frame was displayed from frame 0, but now, the first frame is only displayed when the current frame is equal or greater than the keyframe number.

The previous system was logical when the grease pencil was not an object, but now it seems more logical to display the keyframe if the current frame is equal to or greater than the keyframe number.

Reviewed By: mendio, pepeland

Differential Revision: https://developer.blender.org/D7851

source/blender/blenkernel/intern/gpencil.c

@@ -1011,6 +1011,12 @@ bGPDframe *BKE_gpencil_layer_frame_get(bGPDlayer *gpl, int cframe, eGP_GetFrame_
     }
   }
 
+  /* Don't select first frame if greater than current frame. */
+  if ((gpl->actframe != NULL) && (gpl->actframe == gpl->frames.first) &&
+      (gpl->actframe->framenum > cframe)) {
+    gpl->actframe = NULL;
+  }
+
   /* return */
   return gpl->actframe;
 }
@@ -1878,6 +1884,7 @@ void BKE_gpencil_visible_stroke_iter(ViewLayer *view_layer,
   bGPdata *gpd = (bGPdata *)ob->data;
   const bool is_multiedit = GPENCIL_MULTIEDIT_SESSIONS_ON(gpd);
   const bool is_onion = do_onion && ((gpd->flag & GP_DATA_STROKE_WEIGHTMODE) == 0);
+  const bool is_drawing = (gpd->runtime.sbuffer_used > 0);
 
   /* Onion skinning. */
   const bool onion_mode_abs = (gpd->onion_mode == GP_ONION_MODE_ABSOLUTE);
@@ -1886,6 +1893,8 @@ void BKE_gpencil_visible_stroke_iter(ViewLayer *view_layer,
   const short onion_keytype = gpd->onion_keytype;
 
   LISTBASE_FOREACH (bGPDlayer *, gpl, &gpd->layers) {
+    /* Reset by layer. */
+    bool is_before_first = false;
 
     bGPDframe *act_gpf = gpl->actframe;
     bGPDframe *sta_gpf = act_gpf;
@@ -1924,6 +1933,16 @@ void BKE_gpencil_visible_stroke_iter(ViewLayer *view_layer,
       }
     }
     else if (is_onion && (gpl->onion_flag & GP_LAYER_ONIONSKIN)) {
+      /* Special cases when cframe is before first frame. */
+      bGPDframe *gpf_first = gpl->frames.first;
+      if ((gpf_first != NULL) && (act_gpf != NULL) && (gpf_first->framenum > act_gpf->framenum)) {
+        is_before_first = true;
+      }
+      if ((gpf_first != NULL) && (act_gpf == NULL)) {
+        act_gpf = gpf_first;
+        is_before_first = true;
+      }
+
       if (act_gpf) {
         bGPDframe *last_gpf = gpl->frames.last;
 
@@ -1938,6 +1957,10 @@ void BKE_gpencil_visible_stroke_iter(ViewLayer *view_layer,
           int delta = (onion_mode_abs) ? (gpf->framenum - cfra) :
                                          (gpf->runtime.frameid - act_gpf->runtime.frameid);
 
+          if (is_before_first) {
+            delta++;
+          }
+
           if (onion_mode_sel) {
             is_in_range = (gpf->flag & GP_FRAME_SELECT) != 0;
           }
@@ -1957,7 +1980,9 @@ void BKE_gpencil_visible_stroke_iter(ViewLayer *view_layer,
           gpf->runtime.onion_id = (is_wrong_keytype || !is_in_range) ? INT_MAX : delta;
         }
         /* Active frame is always shown. */
-        act_gpf->runtime.onion_id = 0;
+        if (!is_before_first || is_drawing) {
+          act_gpf->runtime.onion_id = 0;
+        }
       }
 
       sta_gpf = gpl->frames.first;
@@ -1977,10 +2002,15 @@ void BKE_gpencil_visible_stroke_iter(ViewLayer *view_layer,
 
     /* Draw multiedit/onion skinning first */
     for (bGPDframe *gpf = sta_gpf; gpf && gpf != end_gpf; gpf = gpf->next) {
-      if (gpf->runtime.onion_id == INT_MAX || gpf == act_gpf) {
+      if ((gpf->runtime.onion_id == INT_MAX || gpf == act_gpf) && (!is_before_first)) {
         continue;
       }
 
+      /* Only do once for frame before first. */
+      if (is_before_first && gpf == act_gpf) {
+        is_before_first = false;
+      }
+
       if (layer_cb) {
         layer_cb(gpl, gpf, NULL, thunk);
       }
@@ -1995,8 +2025,8 @@ void BKE_gpencil_visible_stroke_iter(ViewLayer *view_layer,
     /* Draw Active frame on top. */
     /* Use evaluated frame (with modifiers for active stroke)/ */
     act_gpf = gpl->actframe;
-    act_gpf->runtime.onion_id = 0;
     if (act_gpf) {
+      act_gpf->runtime.onion_id = 0;
       if (layer_cb) {
         layer_cb(gpl, act_gpf, NULL, thunk);
       }

source/blender/editors/gpencil/gpencil_paint.c

@@ -2127,7 +2127,12 @@ static void gp_paint_initstroke(tGPsdata *p, eGPencil_PaintModes paintmode, Deps
       add_frame_mode = GP_GETFRAME_ADD_NEW;
     }
 
+    bool need_tag = p->gpl->actframe == NULL;
     p->gpf = BKE_gpencil_layer_frame_get(p->gpl, CFRA, add_frame_mode);
+    /* Only if there wasn't an active frame, need update. */
+    if (need_tag) {
+      DEG_id_tag_update(&p->gpd->id, ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
+    }
 
     if (p->gpf == NULL) {
       p->status = GP_STATUS_ERROR;

source/blender/editors/gpencil/gpencil_primitive.c

@@ -1308,7 +1308,12 @@ static void gpencil_primitive_interaction_end(bContext *C,
     add_frame_mode = GP_GETFRAME_ADD_NEW;
   }
 
+  bool need_tag = tgpi->gpl->actframe == NULL;
   gpf = BKE_gpencil_layer_frame_get(tgpi->gpl, tgpi->cframe, add_frame_mode);
+  /* Only if there wasn't an active frame, need update. */
+  if (need_tag) {
+    DEG_id_tag_update(&tgpi->gpd->id, ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
+  }
 
   /* prepare stroke to get transferred */
   gps = tgpi->gpf->strokes.first;