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, 36 insertions, 0 deletions

diff --git a/intern/cycles/blender/blender_viewport.cpp b/intern/cycles/blender/blender_viewport.cpp
index 93dd8faa450..a74b20f150b 100644
--- a/intern/cycles/blender/blender_viewport.cpp
+++ b/intern/cycles/blender/blender_viewport.cpp
@@ -15,6 +15,8 @@
  */
 #include "blender_viewport.h"
 
+#include "blender_util.h"
+
 CCL_NAMESPACE_BEGIN
 
 BlenderViewportParameters::BlenderViewportParameters()
@@ -59,4 +61,38 @@ const bool BlenderViewportParameters::custom_viewport_parameters() const
   return !(use_scene_world && use_scene_lights);
 }
 
+PassType BlenderViewportParameters::get_viewport_display_render_pass(BL::SpaceView3D &b_v3d)
+{
+  PassType display_pass = PASS_NONE;
+  if (b_v3d) {
+    BL::View3DShading b_view3dshading = b_v3d.shading();
+    PointerRNA cshading = RNA_pointer_get(&b_view3dshading.ptr, "cycles");
+    display_pass = (PassType)get_enum(cshading, "render_pass", -1, -1);
+  }
+  return display_pass;
+}
+
+PassType update_viewport_display_passes(BL::SpaceView3D &b_v3d,
+                                        vector<Pass> &passes,
+                                        bool reset_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);
+    }
+
+    return display_pass;
+  }
+  return PASS_NONE;
+}
+
 CCL_NAMESPACE_END