Cycles: Viewport Rendering Memory Improvement

Small memory reduction change by only storing the pixels of the combined
pass when it is being shown in the viewport. Previously the combined pass
was always calculated and present in the output buffer. The combined pass
will still be calculated.

It is a limitation in Blender that Cycles always had a combined pass.
This patch will remove the limitation from the code base of Cycles.
Blender still has the limitation, but will always request the combined
renderpass when doing final rendering.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D5784

7 files changed, 9 insertions, 24 deletions

diff --git a/intern/cycles/blender/blender_camera.cpp b/intern/cycles/blender/blender_camera.cpp
index 3b19e78894a..c84d6e1572b 100644
--- a/intern/cycles/blender/blender_camera.cpp
+++ b/intern/cycles/blender/blender_camera.cpp
@@ -899,7 +899,7 @@ BufferParams BlenderSync::get_buffer_params(BL::RenderSettings &b_render,
     params.height = height;
   }
 
-  update_viewport_display_passes(b_v3d, params.passes, false);
+  update_viewport_display_passes(b_v3d, params.passes);
 
   return params;
 }
diff --git a/intern/cycles/blender/blender_sync.cpp b/intern/cycles/blender/blender_sync.cpp
index 1a166d171bc..f04455ff75e 100644
--- a/intern/cycles/blender/blender_sync.cpp
+++ b/intern/cycles/blender/blender_sync.cpp
@@ -344,7 +344,7 @@ void BlenderSync::sync_film(BL::SpaceView3D &b_v3d)
   Film prevfilm = *film;
 
   if (b_v3d) {
-    film->display_pass = update_viewport_display_passes(b_v3d, film->passes, true);
+    film->display_pass = update_viewport_display_passes(b_v3d, film->passes);
   }
 
   film->exposure = get_float(cscene, "film_exposure");
@@ -520,7 +520,6 @@ int BlenderSync::get_denoising_pass(BL::RenderPass &b_pass)
 vector<Pass> BlenderSync::sync_render_passes(BL::RenderLayer &b_rlay, BL::ViewLayer &b_view_layer)
 {
   vector<Pass> passes;
-  Pass::add(PASS_COMBINED, passes);
 
   /* loop over passes */
   BL::RenderLayer::passes_iterator b_pass_iter;
diff --git a/intern/cycles/blender/blender_viewport.cpp b/intern/cycles/blender/blender_viewport.cpp
index a74b20f150b..73ef5f94720 100644
--- a/intern/cycles/blender/blender_viewport.cpp
+++ b/intern/cycles/blender/blender_viewport.cpp
@@ -72,23 +72,13 @@ PassType BlenderViewportParameters::get_viewport_display_render_pass(BL::SpaceVi
   return display_pass;
 }
 
-PassType update_viewport_display_passes(BL::SpaceView3D &b_v3d,
-                                        vector<Pass> &passes,
-                                        bool reset_passes)
+PassType update_viewport_display_passes(BL::SpaceView3D &b_v3d, vector<Pass> &passes)
 {
   if (b_v3d) {
     PassType display_pass = BlenderViewportParameters::get_viewport_display_render_pass(b_v3d);
 
-    if (reset_passes) {
-      passes.clear();
-      /* We always need a combined pass for now. It would be a good optimization
-       * to support rendering without combined pass. */
-      Pass::add(PASS_COMBINED, passes);
-    }
-
-    if (display_pass != PASS_COMBINED) {
-      Pass::add(display_pass, passes);
-    }
+    passes.clear();
+    Pass::add(display_pass, passes);
 
     return display_pass;
   }
diff --git a/intern/cycles/blender/blender_viewport.h b/intern/cycles/blender/blender_viewport.h
index 564c4f2b210..f26d0d38115 100644
--- a/intern/cycles/blender/blender_viewport.h
+++ b/intern/cycles/blender/blender_viewport.h
@@ -49,9 +49,7 @@ class BlenderViewportParameters {
   static PassType get_viewport_display_render_pass(BL::SpaceView3D &b_v3d);
 };
 
-PassType update_viewport_display_passes(BL::SpaceView3D &b_v3d,
-                                        vector<Pass> &passes,
-                                        bool reset_passes);
+PassType update_viewport_display_passes(BL::SpaceView3D &b_v3d, vector<Pass> &passes);
 
 CCL_NAMESPACE_END
 
diff --git a/intern/cycles/kernel/kernel_passes.h b/intern/cycles/kernel/kernel_passes.h
index 4a424866efe..c1d74dddc2a 100644
--- a/intern/cycles/kernel/kernel_passes.h
+++ b/intern/cycles/kernel/kernel_passes.h
@@ -397,7 +397,9 @@ ccl_device_inline void kernel_write_result(KernelGlobals *kg,
   float alpha;
   float3 L_sum = path_radiance_clamp_and_sum(kg, L, &alpha);
 
-  kernel_write_pass_float4(buffer, make_float4(L_sum.x, L_sum.y, L_sum.z, alpha));
+  if (kernel_data.film.pass_flag & PASSMASK(COMBINED)) {
+    kernel_write_pass_float4(buffer, make_float4(L_sum.x, L_sum.y, L_sum.z, alpha));
+  }
 
   kernel_write_light_passes(kg, buffer, L);
 
diff --git a/intern/cycles/render/buffers.cpp b/intern/cycles/render/buffers.cpp
index ad3827df7e3..49e15d9eaf1 100644
--- a/intern/cycles/render/buffers.cpp
+++ b/intern/cycles/render/buffers.cpp
@@ -43,8 +43,6 @@ BufferParams::BufferParams()
   denoising_data_pass = false;
   denoising_clean_pass = false;
   denoising_prefiltered_pass = false;
-
-  Pass::add(PASS_COMBINED, passes);
 }
 
 void BufferParams::get_offset_stride(int &offset, int &stride)
diff --git a/intern/cycles/render/film.cpp b/intern/cycles/render/film.cpp
index 5bf7ba97515..7f5bec2a66e 100644
--- a/intern/cycles/render/film.cpp
+++ b/intern/cycles/render/film.cpp
@@ -293,8 +293,6 @@ NODE_DEFINE(Film)
 
 Film::Film() : Node(node_type)
 {
-  Pass::add(PASS_COMBINED, passes);
-
   use_light_visibility = false;
   filter_table_offset = TABLE_OFFSET_INVALID;
   cryptomatte_passes = CRYPT_NONE;