Fix deadlock happening when using Save Buffers for render

Summary:
Issue was caused by the same tile being written twice to
the EXR file. This was happening because of partial update
of work-in-progress tiles was merging result to the final
render result in order to make color management pipeline
happy.

We need to avoid such a merges and keep memory usage as
low as possible when Save Buffers is enabled.

Now render pipeline will allocate special display buffer
in render layer which will contain combined pass in the
display space. This keeps memory usage as low as we can
do at this moment.

There's one weak thing which is changing color management
settings during rendering would lead to lossy conversion.
This is because render result's display buffer uses color
space from the time when rendering was invoked.

This is actually what was happening in previous release
already actually so not a big issue.

Reviewers: brecht

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D162

1 files changed, 54 insertions, 26 deletions

diff --git a/source/blender/editors/render/render_internal.c b/source/blender/editors/render/render_internal.c
index b4414cf3f54..deec4225eb9 100644
--- a/source/blender/editors/render/render_internal.c
+++ b/source/blender/editors/render/render_internal.c
@@ -49,6 +49,7 @@
 
 #include "BKE_blender.h"
 #include "BKE_context.h"
+#include "BKE_colortools.h"
 #include "BKE_depsgraph.h"
 #include "BKE_freestyle.h"
 #include "BKE_global.h"
@@ -93,13 +94,39 @@
 /* Render Callbacks */
 static int render_break(void *rjv);
 
+typedef struct RenderJob {
+	Main *main;
+	Scene *scene;
+	Render *re;
+	SceneRenderLayer *srl;
+	struct Object *camera_override;
+	int lay_override;
+	bool v3d_override;
+	short anim, write_still;
+	Image *image;
+	ImageUser iuser;
+	bool image_outdated;
+	short *stop;
+	short *do_update;
+	float *progress;
+	ReportList *reports;
+	int orig_layer;
+	int last_layer;
+	ScrArea *sa;
+	ColorManagedViewSettings view_settings;
+	ColorManagedDisplaySettings display_settings;
+} RenderJob;
+
 /* called inside thread! */
-static void image_buffer_rect_update(Scene *scene, RenderResult *rr, ImBuf *ibuf, ImageUser *iuser, volatile rcti *renrect)
+static void image_buffer_rect_update(RenderJob *rj, RenderResult *rr, ImBuf *ibuf, ImageUser *iuser, volatile rcti *renrect)
 {
+	Scene *scene = rj->scene;
 	float *rectf = NULL;
 	int ymin, ymax, xmin, xmax;
 	int rymin, rxmin;
 	int linear_stride, linear_offset_x, linear_offset_y;
+	ColorManagedViewSettings *view_settings;
+	ColorManagedDisplaySettings *display_settings;
 
 	if (ibuf->userflags & IB_DISPLAY_BUFFER_INVALID) {
 		/* The whole image buffer it so be color managed again anyway. */
@@ -189,10 +216,23 @@ static void image_buffer_rect_update(Scene *scene, RenderResult *rr, ImBuf *ibuf
 		linear_offset_y = 0;
 	}
 
+	if (rr->do_exr_tile) {
+		/* We don't support changing color management settings during rendering
+		 * when using Save Buffers option.
+		 */
+		view_settings = &rj->view_settings;
+		display_settings = &rj->display_settings;
+	}
+	else {
+		view_settings = &scene->view_settings;
+		display_settings = &scene->display_settings;
+	}
+
 	IMB_partial_display_buffer_update(ibuf, rectf, NULL,
 	                                  linear_stride, linear_offset_x, linear_offset_y,
-	                                  &scene->view_settings, &scene->display_settings,
-	                                  rxmin, rymin, rxmin + xmax, rymin + ymax);
+	                                  view_settings, display_settings,
+	                                  rxmin, rymin, rxmin + xmax, rymin + ymax,
+	                                  rr->do_exr_tile);
 }
 
 /* ****************************** render invoking ***************** */
@@ -286,31 +326,11 @@ static int screen_render_exec(bContext *C, wmOperator *op)
 	return OPERATOR_FINISHED;
 }
 
-typedef struct RenderJob {
-	Main *main;
-	Scene *scene;
-	Render *re;
-	SceneRenderLayer *srl;
-	struct Object *camera_override;
-	int lay_override;
-	bool v3d_override;
-	short anim, write_still;
-	Image *image;
-	ImageUser iuser;
-	bool image_outdated;
-	short *stop;
-	short *do_update;
-	float *progress;
-	ReportList *reports;
-	int orig_layer;
-	int last_layer;
-	ScrArea *sa;
-} RenderJob;
-
 static void render_freejob(void *rjv)
 {
 	RenderJob *rj = rjv;
 
+	BKE_color_managed_view_settings_free(&rj->view_settings);
 	MEM_freeN(rj);
 }
 
@@ -516,11 +536,16 @@ static void image_rect_update(void *rjv, RenderResult *rr, volatile rcti *renrec
 	if (ibuf) {
 		/* Don't waste time on CPU side color management if
 		 * image will be displayed using GLSL.
+		 *
+		 * Need to update rect if Save Buffers enabled because in
+		 * this case GLSL doesn't have original float buffer to
+		 * operate with.
 		 */
-		if (ibuf->channels == 1 ||
+		if (rr->do_exr_tile ||
+		    ibuf->channels == 1 ||
 		    U.image_draw_method != IMAGE_DRAW_METHOD_GLSL)
 		{
-			image_buffer_rect_update(rj->scene, rr, ibuf, &rj->iuser, renrect);
+			image_buffer_rect_update(rj, rr, ibuf, &rj->iuser, renrect);
 		}
 
 		/* make jobs timer to send notifier */
@@ -793,6 +818,9 @@ static int screen_render_invoke(bContext *C, wmOperator *op, const wmEvent *even
 	rj->last_layer = 0;
 	rj->sa = sa;
 
+	BKE_color_managed_display_settings_copy(&rj->display_settings, &scene->display_settings);
+	BKE_color_managed_view_settings_copy(&rj->view_settings, &scene->view_settings);
+
 	if (sa) {
 		SpaceImage *sima = sa->spacedata.first;
 		rj->orig_layer = sima->iuser.layer;