Refactor depsgraph/render logic to serve evaluated depsgraph to engines

User notes
----------
Compositing, rendering of multi-layers in Eevee should be fully working now.

Development notes
-----------------
Up until now we were still using the same depsgraph for rendering and viewport
evaluation. And we had to go out of our ways to be sure the depsgraphs were
updated.

Now we iterate over the (to be rendered) view layers and create a depsgraph to
each one, fully evaluated and call the render engines (Cycles, Eevee, ...) with
this viewlayer/depsgraph/evaluation context.

At this time we are not handling data persistency, Depsgraph is created from
scratch prior to rendering each frame.  So I got rid of most of the partial
update calls we had during the render pipeline.

Cycles: Brecht Van Lommel did a patch to tackle some of the required Cycles
changes but this commit mark these changes as TODOs. Basically Cycles needs to
render one layer at a time.

Reviewers: sergey, brecht

Differential Revision: https://developer.blender.org/D3073

4 files changed, 28 insertions, 6 deletions

diff --git a/source/blender/render/intern/include/pointdensity.h b/source/blender/render/intern/include/pointdensity.h
index 1d1e808e8d3..f122b3dc4c1 100644
--- a/source/blender/render/intern/include/pointdensity.h
+++ b/source/blender/render/intern/include/pointdensity.h
@@ -37,13 +37,14 @@
  * Make point density kd-trees for all point density textures in the scene
  */
 
+struct EvaluationContext;
 struct PointDensity;
 struct Render;
 struct TexResult;
 
 void free_pointdensity(struct PointDensity *pd);
-void cache_pointdensity(struct Render *re, struct PointDensity *pd);
-void make_pointdensities(struct Render *re);
+void cache_pointdensity(const struct EvaluationContext *eval_ctx, struct Render *re, struct PointDensity *pd);
+void make_pointdensities(const struct EvaluationContext *eval_ctx, struct Render *re);
 void free_pointdensities(struct Render *re);
 int pointdensitytex(struct Tex *tex, const float texvec[3], struct TexResult *texres);
 
diff --git a/source/blender/render/intern/include/render_result.h b/source/blender/render/intern/include/render_result.h
index 8d293c938c7..b2c5758f506 100644
--- a/source/blender/render/intern/include/render_result.h
+++ b/source/blender/render/intern/include/render_result.h
@@ -117,5 +117,28 @@ void render_result_views_shallowcopy(struct RenderResult *dst, struct RenderResu
 void render_result_views_shallowdelete(struct RenderResult *rr);
 bool render_result_has_views(struct RenderResult *rr);
 
+#define FOREACH_VIEW_LAYER_TO_RENDER(re_, iter_)          \
+{                                                         \
+	int nr;                                               \
+	ViewLayer *iter_;                                     \
+	for (nr = 0, iter_ = (re_)->view_layers.first;        \
+	     iter_ != NULL;                                   \
+         iter_ = iter_->next, nr++)                       \
+	{                                                     \
+		if ((re_)->r.scemode & R_SINGLE_LAYER) {          \
+			if (nr != re->active_view_layer) {            \
+				continue;                                 \
+			}                                             \
+		}                                                 \
+		else {                                            \
+			if ((iter_->flag & VIEW_LAYER_RENDER) == 0) { \
+				continue;                                 \
+			}                                             \
+		}
+
+#define FOREACH_VIEW_LAYER_TO_RENDER_END                  \
+	}                                                     \
+}
+
 #endif /* __RENDER_RESULT_H__ */
 
diff --git a/source/blender/render/intern/include/render_types.h b/source/blender/render/intern/include/render_types.h
index d24aae6ac97..2c46138c7ea 100644
--- a/source/blender/render/intern/include/render_types.h
+++ b/source/blender/render/intern/include/render_types.h
@@ -185,8 +185,6 @@ struct Render {
 	
 	/* shadow counter, detect shadow-reuse for shaders */
 	int shadowsamplenr[BLENDER_MAX_THREADS];
-	
-	struct Depsgraph *depsgraph;
 
 	/* main, scene, and its full copy of renderdata and world */
 	struct Main *main;
@@ -280,7 +278,6 @@ struct Render {
 	struct ReportList *reports;
 
 	struct ImagePool *pool;
-	struct EvaluationContext *eval_ctx;
 
 	void **movie_ctx_arr;
 	char viewname[MAX_NAME];
diff --git a/source/blender/render/intern/include/renderdatabase.h b/source/blender/render/intern/include/renderdatabase.h
index b576d69d806..1d1af7092c8 100644
--- a/source/blender/render/intern/include/renderdatabase.h
+++ b/source/blender/render/intern/include/renderdatabase.h
@@ -40,6 +40,7 @@ extern "C" {
 struct Object;
 struct VlakRen;
 struct VertRen;
+struct EvaluationContext;
 struct HaloRen;
 struct Main;
 struct Material;
@@ -164,7 +165,7 @@ void area_lamp_vectors(struct LampRen *lar);
 
 /* convertblender.c */
 void init_render_world(Render *re);
-void RE_Database_FromScene_Vectors(Render *re, struct Main *bmain, struct Scene *sce, unsigned int lay);
+void RE_Database_FromScene_Vectors(struct EvaluationContext *eval_ctx, Render *re, struct Main *bmain, struct Scene *sce, unsigned int lay);
 
 #ifdef __cplusplus
 }