Cycles/BI: Add a pixel size option for speeding up viewport rendering

This patch adds "Pixel Size" to the performance options, which allows to render
in a smaller resolution, which is especially useful for displays with high DPI.

Reviewers: Severin, dingto, sergey, brecht

Reviewed By: brecht

Subscribers: Severin, venomgfx, eyecandy, brecht

Differential Revision: https://developer.blender.org/D1619

2 files changed, 10 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_scene.h b/source/blender/blenkernel/BKE_scene.h
index f1680b6ccbf..b7ecb85819e 100644
--- a/source/blender/blenkernel/BKE_scene.h
+++ b/source/blender/blenkernel/BKE_scene.h
@@ -152,6 +152,8 @@ bool BKE_scene_check_rigidbody_active(const struct Scene *scene);
 int BKE_scene_num_threads(const struct Scene *scene);
 int BKE_render_num_threads(const struct RenderData *r);
 
+int BKE_render_preview_pixel_size(const struct RenderData *r);
+
 double BKE_scene_unit_scale(const struct UnitSettings *unit, const int unit_type, double value);
 
 /* multiview */
diff --git a/source/blender/blenkernel/intern/scene.c b/source/blender/blenkernel/intern/scene.c
index b7fc6e70e65..b8ad54dc533 100644
--- a/source/blender/blenkernel/intern/scene.c
+++ b/source/blender/blenkernel/intern/scene.c
@@ -2411,6 +2411,14 @@ int BKE_scene_num_threads(const Scene *scene)
 	return BKE_render_num_threads(&scene->r);
 }
 
+int BKE_render_preview_pixel_size(const RenderData *r)
+{
+	if (r->preview_pixel_size == 0) {
+		return (U.pixelsize > 1.5f)? 2 : 1;
+	}
+	return r->preview_pixel_size;
+}
+
 /* Apply the needed correction factor to value, based on unit_type (only length-related are affected currently)
  * and unit->scale_length.
  */