Cycles: Display RenderPass in Viewport

This change allows the user to select a renderpass in the 3d viewport.

Added support for external renderers to extend the `View3DShading` struct.
This way Blender doesn't need to know the features an external render engine wants to support.
Note that the View3DShading is also available in the scene->display.shading; although this is
supported, it does not make sense for render engines to put something here as it is really
scene/workbench related.

Currently cycles assumes that it always needs to calculate the combined pass; it ignores the
`pass_flag` in KernelFilm. We could optimize this but that was not in scope of this change

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D5689

1 files changed, 39 insertions, 5 deletions

diff --git a/intern/cycles/render/film.cpp b/intern/cycles/render/film.cpp
index d6c44b66117..5bf7ba97515 100644
--- a/intern/cycles/render/film.cpp
+++ b/intern/cycles/render/film.cpp
@@ -267,7 +267,7 @@ NODE_DEFINE(Film)
   NodeType *type = NodeType::add("film", create);
 
   SOCKET_FLOAT(exposure, "Exposure", 0.8f);
-  SOCKET_FLOAT(pass_alpha_threshold, "Pass Alpha Threshold", 0.5f);
+  SOCKET_FLOAT(pass_alpha_threshold, "Pass Alpha Threshold", 0.0f);
 
   static NodeEnum filter_enum;
   filter_enum.insert("box", FILTER_BOX);
@@ -318,6 +318,13 @@ void Film::device_update(Device *device, DeviceScene *dscene, Scene *scene)
   /* update __data */
   kfilm->exposure = exposure;
   kfilm->pass_flag = 0;
+
+  kfilm->display_pass_stride = -1;
+  kfilm->display_pass_components = 0;
+  kfilm->display_divide_pass_stride = -1;
+  kfilm->use_display_exposure = false;
+  kfilm->use_display_pass_alpha = (display_pass == PASS_COMBINED);
+
   kfilm->light_pass_flag = 0;
   kfilm->pass_stride = 0;
   kfilm->use_light_pass = use_light_visibility || use_sample_clamp;
@@ -464,6 +471,16 @@ void Film::device_update(Device *device, DeviceScene *dscene, Scene *scene)
         break;
     }
 
+    if (pass.type == display_pass) {
+      kfilm->display_pass_stride = kfilm->pass_stride;
+      kfilm->display_pass_components = pass.components;
+      kfilm->use_display_exposure = pass.exposure && (kfilm->exposure != 1.0f);
+    }
+    else if (pass.type == PASS_DIFFUSE_COLOR || pass.type == PASS_TRANSMISSION_COLOR ||
+             pass.type == PASS_GLOSSY_COLOR || pass.type == PASS_SUBSURFACE_COLOR) {
+      kfilm->display_divide_pass_stride = kfilm->pass_stride;
+    }
+
     kfilm->pass_stride += pass.components;
   }
 
@@ -485,7 +502,18 @@ void Film::device_update(Device *device, DeviceScene *dscene, Scene *scene)
   }
 
   kfilm->pass_stride = align_up(kfilm->pass_stride, 4);
-  kfilm->pass_alpha_threshold = pass_alpha_threshold;
+
+  /* When displaying the normal/uv pass in the viewport we need to disable
+   * transparency.
+   *
+   * We also don't need to perform light accumulations. Later we want to optimize this to suppress
+   * light calculations. */
+  if (display_pass == PASS_NORMAL || display_pass == PASS_UV) {
+    kfilm->use_light_pass = 0;
+  }
+  else {
+    kfilm->pass_alpha_threshold = pass_alpha_threshold;
+  }
 
   /* update filter table */
   vector<float> table = filter_table(filter_type, filter_width);
@@ -518,7 +546,7 @@ bool Film::modified(const Film &film)
   return !Node::equals(film) || !Pass::equals(passes, film.passes);
 }
 
-void Film::tag_passes_update(Scene *scene, const vector<Pass> &passes_)
+void Film::tag_passes_update(Scene *scene, const vector<Pass> &passes_, bool update_passes)
 {
   if (Pass::contains(passes, PASS_UV) != Pass::contains(passes_, PASS_UV)) {
     scene->mesh_manager->tag_update(scene);
@@ -526,10 +554,16 @@ void Film::tag_passes_update(Scene *scene, const vector<Pass> &passes_)
     foreach (Shader *shader, scene->shaders)
       shader->need_update_mesh = true;
   }
-  else if (Pass::contains(passes, PASS_MOTION) != Pass::contains(passes_, PASS_MOTION))
+  else if (Pass::contains(passes, PASS_MOTION) != Pass::contains(passes_, PASS_MOTION)) {
     scene->mesh_manager->tag_update(scene);
+  }
+  else if (Pass::contains(passes, PASS_AO) != Pass::contains(passes_, PASS_AO)) {
+    scene->integrator->tag_update(scene);
+  }
 
-  passes = passes_;
+  if (update_passes) {
+    passes = passes_;
+  }
 }
 
 void Film::tag_update(Scene * /*scene*/)