Sequencer: nested scene strip support (like metas)

This makes it possible to use scenes as a kind of
multi-user meta-strip (with their own time).

Currently this supports rendering & drawing nested strips,
but no convenient way to tab-enter into a scene strip.

7 files changed, 141 insertions, 35 deletions

diff --git a/release/scripts/startup/bl_ui/space_sequencer.py b/release/scripts/startup/bl_ui/space_sequencer.py
index eb4625d2dac..b08bff13967 100644
--- a/release/scripts/startup/bl_ui/space_sequencer.py
+++ b/release/scripts/startup/bl_ui/space_sequencer.py
@@ -827,11 +827,13 @@ class SEQUENCER_PT_scene(SequencerButtonsPanel, Panel):
         layout.template_ID(strip, "scene")
 
         scene = strip.scene
+        layout.prop(strip, "use_sequence")
 
-        layout.label(text="Camera Override")
-        layout.template_ID(strip, "scene_camera")
+        if not strip.use_sequence:
+            layout.label(text="Camera Override")
+            layout.template_ID(strip, "scene_camera")
 
-        layout.prop(strip, "use_grease_pencil", text="Show Grease Pencil")
+            layout.prop(strip, "use_grease_pencil", text="Show Grease Pencil")
 
         if scene:
             layout.prop(scene, "audio_volume", text="Audio Volume")
diff --git a/source/blender/blenkernel/BKE_sequencer.h b/source/blender/blenkernel/BKE_sequencer.h
index 11f2d0e0816..3f2712e0ae1 100644
--- a/source/blender/blenkernel/BKE_sequencer.h
+++ b/source/blender/blenkernel/BKE_sequencer.h
@@ -237,6 +237,7 @@ void BKE_sequencer_base_clipboard_pointers_restore(struct ListBase *seqbase, str
 void BKE_sequence_free(struct Scene *scene, struct Sequence *seq);
 void BKE_sequence_free_anim(struct Sequence *seq);
 const char *BKE_sequence_give_name(struct Sequence *seq);
+ListBase *BKE_sequence_seqbase_get(struct Sequence *seq, int *r_offset);
 void BKE_sequence_calc(struct Scene *scene, struct Sequence *seq);
 void BKE_sequence_calc_disp(struct Scene *scene, struct Sequence *seq);
 void BKE_sequence_reload_new_file(struct Scene *scene, struct Sequence *seq, const bool lock_range);
diff --git a/source/blender/blenkernel/intern/sequencer.c b/source/blender/blenkernel/intern/sequencer.c
index a87935ae23b..6e722e7bc63 100644
--- a/source/blender/blenkernel/intern/sequencer.c
+++ b/source/blender/blenkernel/intern/sequencer.c
@@ -91,6 +91,8 @@
 #  include AUD_SPECIAL_H
 #endif
 
+#define USE_SCENE_RECURSIVE_HACK
+
 static ImBuf *seq_render_strip_stack(const SeqRenderData *context, ListBase *seqbasep, float cfra, int chanshown);
 static ImBuf *seq_render_strip(const SeqRenderData *context, Sequence *seq, float cfra);
 static void seq_free_animdata(Scene *scene, Sequence *seq);
@@ -1149,6 +1151,33 @@ const char *BKE_sequence_give_name(Sequence *seq)
 	return name;
 }
 
+ListBase *BKE_sequence_seqbase_get(Sequence *seq, int *r_offset)
+{
+	ListBase *seqbase = NULL;
+
+	switch (seq->type) {
+		case SEQ_TYPE_META:
+		{
+			seqbase = &seq->seqbase;
+			*r_offset = seq->start;
+			break;
+		}
+		case SEQ_TYPE_SCENE:
+		{
+			if (seq->flag & SEQ_SCENE_STRIPS) {
+				Editing *ed = BKE_sequencer_editing_get(seq->scene, false);
+				if (ed) {
+					seqbase = &ed->seqbase;
+					*r_offset = seq->scene->r.sfra;
+				}
+			}
+			break;
+		}
+	}
+
+	return seqbase;
+}
+
 /*********************** DO THE SEQUENCE *************************/
 
 static void make_black_ibuf(ImBuf *ibuf)
@@ -3319,6 +3348,40 @@ finally:
 	return ibuf;
 }
 
+/**
+ * Used for meta-strips & scenes with #SEQ_SCENE_STRIPS flag set.
+ */
+static ImBuf *do_render_strip_seqbase(
+        const SeqRenderData *context, Sequence *seq, float nr,
+        bool use_preprocess)
+{
+	ImBuf *meta_ibuf = NULL, *ibuf = NULL;
+	ListBase *seqbase = NULL;
+	int offset;
+
+	seqbase = BKE_sequence_seqbase_get(seq, &offset);
+
+	if (seqbase && !BLI_listbase_is_empty(seqbase)) {
+		meta_ibuf = seq_render_strip_stack(
+		        context, seqbase,
+		        /* scene strips don't have their start taken into account */
+		        nr + offset, 0);
+	}
+
+	if (meta_ibuf) {
+		ibuf = meta_ibuf;
+		if (ibuf && use_preprocess) {
+			ImBuf *i = IMB_dupImBuf(ibuf);
+
+			IMB_freeImBuf(ibuf);
+
+			ibuf = i;
+		}
+	}
+
+	return ibuf;
+}
+
 static ImBuf *do_render_strip_uncached(const SeqRenderData *context, Sequence *seq, float cfra)
 {
 	ImBuf *ibuf = NULL;
@@ -3329,22 +3392,38 @@ static ImBuf *do_render_strip_uncached(const SeqRenderData *context, Sequence *s
 	switch (type) {
 		case SEQ_TYPE_META:
 		{
-			ImBuf *meta_ibuf = NULL;
-
-			if (seq->seqbase.first)
-				meta_ibuf = seq_render_strip_stack(context, &seq->seqbase, seq->start + nr, 0);
+			ibuf = do_render_strip_seqbase(context, seq, nr, use_preprocess);
+			break;
+		}
 
-			if (meta_ibuf) {
-				ibuf = meta_ibuf;
-				if (ibuf && use_preprocess) {
-					ImBuf *i = IMB_dupImBuf(ibuf);
+		case SEQ_TYPE_SCENE:
+		{
+			if (seq->flag & SEQ_SCENE_STRIPS) {
+				if (seq->scene && (context->scene != seq->scene)) {
+#ifdef USE_SCENE_RECURSIVE_HACK
+					/* weak recusrive check, same as T32017 */
+					if (seq->scene->id.flag & LIB_DOIT) {
+						break;
+					}
+					seq->scene->id.flag |= LIB_DOIT;
+#endif
 
-					IMB_freeImBuf(ibuf);
+					ibuf = do_render_strip_seqbase(context, seq, nr, use_preprocess);
 
-					ibuf = i;
+#ifdef USE_SCENE_RECURSIVE_HACK
+					seq->scene->id.flag &= ~LIB_DOIT;
+#endif
 				}
 			}
+			else {
+				/* scene can be NULL after deletions */
+				ibuf = seq_render_scene_strip(context, seq, nr, cfra);
 
+				/* Scene strips update all animation, so we need to restore original state.*/
+				BKE_animsys_evaluate_all_animation(context->bmain, context->scene, cfra);
+
+				copy_to_ibuf_still(context, seq, nr, ibuf);
+			}
 			break;
 		}
 
@@ -3395,18 +3474,6 @@ static ImBuf *do_render_strip_uncached(const SeqRenderData *context, Sequence *s
 			break;
 		}
 
-		case SEQ_TYPE_SCENE:
-		{
-			/* scene can be NULL after deletions */
-			ibuf = seq_render_scene_strip(context, seq, nr, cfra);
-
-			/* Scene strips update all animation, so we need to restore original state.*/
-			BKE_animsys_evaluate_all_animation(context->bmain, context->scene, cfra);
-
-			copy_to_ibuf_still(context, seq, nr, ibuf);
-			break;
-		}
-
 		case SEQ_TYPE_MOVIECLIP:
 		{
 			ibuf = seq_render_movieclip_strip(context, seq, nr);
@@ -3731,6 +3798,10 @@ ImBuf *BKE_sequencer_give_ibuf(const SeqRenderData *context, float cfra, int cha
 		seqbasep = ed->seqbasep;
 	}
 
+#ifdef USE_SCENE_RECURSIVE_HACK
+	BKE_main_id_tag_idcode(context->bmain, ID_SCE, false);
+#endif
+
 	return seq_render_strip_stack(context, seqbasep, cfra, chanshown);
 }
 
diff --git a/source/blender/editors/space_sequencer/sequencer_draw.c b/source/blender/editors/space_sequencer/sequencer_draw.c
index 2ae7cdd4f98..ebc41878910 100644
--- a/source/blender/editors/space_sequencer/sequencer_draw.c
+++ b/source/blender/editors/space_sequencer/sequencer_draw.c
@@ -301,6 +301,20 @@ static void drawmeta_contents(Scene *scene, Sequence *seqm, float x1, float y1,
 	int chan_range = 0;
 	float draw_range = y2 - y1;
 	float draw_height;
+	ListBase *seqbase;
+	int offset;
+
+	seqbase = BKE_sequence_seqbase_get(seqm, &offset);
+	if (!seqbase || BLI_listbase_is_empty(seqbase)) {
+		return;
+	}
+
+	if (seqm->type == SEQ_TYPE_SCENE) {
+		offset  = seqm->start - offset;
+	}
+	else {
+		offset = 0;
+	}
 
 	glEnable(GL_BLEND);
 	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
@@ -308,7 +322,7 @@ static void drawmeta_contents(Scene *scene, Sequence *seqm, float x1, float y1,
 	if (seqm->flag & SEQ_MUTE)
 		drawmeta_stipple(1);
 
-	for (seq = seqm->seqbase.first; seq; seq = seq->next) {
+	for (seq = seqbase->first; seq; seq = seq->next) {
 		chan_min = min_ii(chan_min, seq->machine);
 		chan_max = max_ii(chan_max, seq->machine);
 	}
@@ -318,11 +332,14 @@ static void drawmeta_contents(Scene *scene, Sequence *seqm, float x1, float y1,
 
 	col[3] = 196; /* alpha, used for all meta children */
 
-	for (seq = seqm->seqbase.first; seq; seq = seq->next) {
-		if ((seq->startdisp > x2 || seq->enddisp < x1) == 0) {
+	for (seq = seqbase->first; seq; seq = seq->next) {
+		const int startdisp = seq->startdisp + offset;
+		const int enddisp   = seq->enddisp   + offset;
+
+		if ((startdisp > x2 || enddisp < x1) == 0) {
 			float y_chan = (seq->machine - chan_min) / (float)(chan_range) * draw_range;
-			float x1_chan = seq->startdisp;
-			float x2_chan = seq->enddisp;
+			float x1_chan = startdisp;
+			float x2_chan = enddisp;
 			float y1_chan, y2_chan;
 
 			if ((seqm->flag & SEQ_MUTE) == 0 && (seq->flag & SEQ_MUTE))
@@ -830,7 +847,9 @@ static void draw_seq_strip(const bContext *C, SpaceSeq *sseq, Scene *scene, AReg
 		glDisable(GL_LINE_STIPPLE);
 	}
 	
-	if (seq->type == SEQ_TYPE_META) {
+	if ((seq->type == SEQ_TYPE_META) ||
+	    ((seq->type == SEQ_TYPE_SCENE) && (seq->flag & SEQ_SCENE_STRIPS)))
+	{
 		drawmeta_contents(scene, seq, x1, y1, x2, y2);
 	}
 	
diff --git a/source/blender/makesdna/DNA_sequence_types.h b/source/blender/makesdna/DNA_sequence_types.h
index 69e7fb43fb6..e5c102b1d2d 100644
--- a/source/blender/makesdna/DNA_sequence_types.h
+++ b/source/blender/makesdna/DNA_sequence_types.h
@@ -417,6 +417,9 @@ enum {
 	SEQ_SCENE_NO_GPENCIL        = (1 << 28),
 	SEQ_USE_VIEWS               = (1 << 29),
 
+	/* access scene strips directly (like a metastrip) */
+	SEQ_SCENE_STRIPS            = (1 << 30),
+
 	SEQ_INVALID_EFFECT          = (1 << 31),
 };
 
diff --git a/source/blender/makesrna/intern/rna_sequencer.c b/source/blender/makesrna/intern/rna_sequencer.c
index de138699e3a..1fb57fc1d11 100644
--- a/source/blender/makesrna/intern/rna_sequencer.c
+++ b/source/blender/makesrna/intern/rna_sequencer.c
@@ -1901,7 +1901,12 @@ static void rna_def_scene(BlenderRNA *brna)
 	RNA_def_property_pointer_funcs(prop, NULL, NULL, NULL, "rna_Camera_object_poll");
 	RNA_def_property_ui_text(prop, "Camera Override", "Override the scenes active camera");
 	RNA_def_property_update(prop, NC_SCENE | ND_SEQUENCER, "rna_Sequence_update");
-	
+
+	prop = RNA_def_property(srna, "use_sequence", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_sdna(prop, NULL, "flag", SEQ_SCENE_STRIPS);
+	RNA_def_property_ui_text(prop, "Use Sequence", "Use scenes sequence strips directly, instead of rendering");
+	RNA_def_property_update(prop, NC_SCENE | ND_SEQUENCER, "rna_Sequence_update");
+
 	prop = RNA_def_property(srna, "use_grease_pencil", PROP_BOOLEAN, PROP_NONE);
 	RNA_def_property_boolean_negative_sdna(prop, NULL, "flag", SEQ_SCENE_NO_GPENCIL);
 	RNA_def_property_ui_text(prop, "Use Grease Pencil", "Show Grease Pencil strokes in OpenGL previews");
diff --git a/source/blender/render/intern/source/pipeline.c b/source/blender/render/intern/source/pipeline.c
index 3ae93649ee2..d565b8a657c 100644
--- a/source/blender/render/intern/source/pipeline.c
+++ b/source/blender/render/intern/source/pipeline.c
@@ -2832,6 +2832,8 @@ static bool check_valid_camera_multiview(Scene *scene, Object *camera, ReportLis
 
 static int check_valid_camera(Scene *scene, Object *camera_override, ReportList *reports)
 {
+	const char *err_msg = "No camera found in scene \"%s\"";
+
 	if (camera_override == NULL && scene->camera == NULL)
 		scene->camera = BKE_scene_camera_find(scene);
 
@@ -2843,14 +2845,17 @@ static int check_valid_camera(Scene *scene, Object *camera_override, ReportList
 			Sequence *seq = scene->ed->seqbase.first;
 
 			while (seq) {
-				if (seq->type == SEQ_TYPE_SCENE && seq->scene) {
+				if ((seq->type == SEQ_TYPE_SCENE) &&
+				    ((seq->flag & SEQ_SCENE_STRIPS) == 0) &&
+				    (seq->scene != NULL))
+				{
 					if (!seq->scene_camera) {
 						if (!seq->scene->camera && !BKE_scene_camera_find(seq->scene)) {
 							/* camera could be unneeded due to composite nodes */
 							Object *override = (seq->scene == scene) ? camera_override : NULL;
 
 							if (!check_valid_compositing_camera(seq->scene, override)) {
-								BKE_reportf(reports, RPT_ERROR, "No camera found in scene \"%s\"", seq->scene->id.name+2);
+								BKE_reportf(reports, RPT_ERROR, err_msg, seq->scene->id.name + 2);
 								return false;
 							}
 						}
@@ -2864,7 +2869,7 @@ static int check_valid_camera(Scene *scene, Object *camera_override, ReportList
 		}
 	}
 	else if (!check_valid_compositing_camera(scene, camera_override)) {
-		BKE_report(reports, RPT_ERROR, "No camera found in scene");
+		BKE_reportf(reports, RPT_ERROR, err_msg, scene->id.name + 2);
 		return false;
 	}