EEVEE: Add support for view layer overrides

This was a missing features in EEVEE for ages which
was in fact very easy to implement.

EEVEE implements the sample override like the default
`Use` value in Cycles. It always override the sample
count if not 0. Adding a new option for changing this
behavior just like Cycles can be done later while
at the same time making the option more understandable
and its value moved to the blender's DNA.

This PR moves the UI panel to the Blender side to
be shared between Cycles and EEVEE.

Pull Request: https://projects.blender.org/blender/blender/pulls/140219

intern/cycles/blender/addon/ui.py

@@ -978,23 +978,6 @@ class CYCLES_RENDER_PT_filter(CyclesButtonsPanel, Panel):
         sub.active = scene.cycles.use_denoising
 
 
-class CYCLES_RENDER_PT_override(CyclesButtonsPanel, Panel):
-    bl_label = "Override"
-    bl_options = {'DEFAULT_CLOSED'}
-    bl_context = "view_layer"
-
-    def draw(self, context):
-        layout = self.layout
-        layout.use_property_split = True
-        layout.use_property_decorate = False
-
-        view_layer = context.view_layer
-
-        layout.prop(view_layer, "material_override")
-        layout.prop(view_layer, "world_override")
-        layout.prop(view_layer, "samples")
-
-
 class CYCLES_RENDER_PT_passes(CyclesButtonsPanel, Panel):
     bl_label = "Passes"
     bl_context = "view_layer"
@@ -2566,7 +2549,6 @@ classes = (
     CYCLES_RENDER_PT_passes_aov,
     CYCLES_RENDER_PT_passes_lightgroups,
     CYCLES_RENDER_PT_filter,
-    CYCLES_RENDER_PT_override,
     CYCLES_PT_post_processing,
     CYCLES_CAMERA_PT_dof,
     CYCLES_CAMERA_PT_dof_aperture,

scripts/startup/bl_ui/properties_view_layer.py

@@ -271,6 +271,26 @@ class VIEWLAYER_PT_filter(ViewLayerButtonsPanel, Panel):
         sub.active = scene.render.use_motion_blur
 
 
+class VIEWLAYER_PT_override(ViewLayerButtonsPanel, Panel):
+    bl_label = "Override"
+    bl_options = {'DEFAULT_CLOSED'}
+    COMPAT_ENGINES = {
+        'BLENDER_EEVEE_NEXT',
+        'CYCLES',
+    }
+
+    def draw(self, context):
+        layout = self.layout
+        layout.use_property_split = True
+        layout.use_property_decorate = False
+
+        view_layer = context.view_layer
+
+        layout.prop(view_layer, "material_override")
+        layout.prop(view_layer, "world_override")
+        layout.prop(view_layer, "samples")
+
+
 class VIEWLAYER_PT_layer_custom_props(PropertyPanel, Panel):
     bl_space_type = 'PROPERTIES'
     bl_region_type = 'WINDOW'
@@ -290,6 +310,7 @@ classes = (
     VIEWLAYER_PT_layer_passes_aov,
     VIEWLAYER_PT_layer_passes_lightgroups,
     VIEWLAYER_PT_filter,
+    VIEWLAYER_PT_override,
     VIEWLAYER_PT_layer_custom_props,
     VIEWLAYER_UL_aov,
 )

source/blender/draw/engines/eevee/eevee_material.cc

@@ -164,6 +164,8 @@ void MaterialModule::begin_sync()
   queued_textures_count = 0;
   queued_optimize_shaders_count = 0;
 
+  material_override = DEG_get_evaluated(inst_.depsgraph, inst_.view_layer->mat_override);
+
   uint64_t next_update = GPU_pass_global_compilation_count();
   gpu_pass_last_update_ = gpu_pass_next_update_;
   gpu_pass_next_update_ = next_update;
@@ -530,7 +532,7 @@ MaterialArray &MaterialModule::material_array_get(Object *ob, bool has_motion)
   const int materials_len = BKE_object_material_used_with_fallback_eval(*ob);
 
   for (auto i : IndexRange(materials_len)) {
-    ::Material *blender_mat = material_from_slot(ob, i);
+    ::Material *blender_mat = (material_override) ? material_override : material_from_slot(ob, i);
     Material &mat = material_sync(ob, blender_mat, to_material_geometry(ob), has_motion);
     /* \note Perform a whole copy since next material_sync() can move the Material memory location
      * (i.e: because of its container growing) */
@@ -545,7 +547,8 @@ Material &MaterialModule::material_get(Object *ob,
                                        int mat_nr,
                                        eMaterialGeometry geometry_type)
 {
-  ::Material *blender_mat = material_from_slot(ob, mat_nr);
+  ::Material *blender_mat = (material_override) ? material_override :
+                                                  material_from_slot(ob, mat_nr);
   Material &mat = material_sync(ob, blender_mat, geometry_type, has_motion);
   return mat;
 }

source/blender/draw/engines/eevee/eevee_material.hh

@@ -355,6 +355,8 @@ class MaterialModule {
   ::Material *default_surface;
   ::Material *default_volume;
 
+  ::Material *material_override = nullptr;
+
   int64_t queued_shaders_count = 0;
   int64_t queued_textures_count = 0;
   int64_t queued_optimize_shaders_count = 0;

source/blender/draw/engines/eevee/eevee_sampling.cc

@@ -27,7 +27,12 @@ namespace blender::eevee {
 
 void Sampling::init(const Scene *scene)
 {
-  sample_count_ = inst_.is_viewport() ? scene->eevee.taa_samples : scene->eevee.taa_render_samples;
+  /* Note: Cycles have different option for view layers sample overrides. The current behavior
+   * matches the default `Use`, which simply override if non-zero. */
+  uint64_t render_sample_count = (inst_.view_layer->samples > 0) ? inst_.view_layer->samples :
+                                                                   scene->eevee.taa_render_samples;
+
+  sample_count_ = inst_.is_viewport() ? scene->eevee.taa_samples : render_sample_count;
 
   if (inst_.is_image_render) {
     sample_count_ = math::max(uint64_t(1), sample_count_);

source/blender/draw/engines/eevee/eevee_world.cc

@@ -126,6 +126,11 @@ void World::sync()
     bl_world = scene_world_get();
   }
 
+  ::World *world_override = DEG_get_evaluated(inst_.depsgraph, inst_.view_layer->world_override);
+  if (world_override) {
+    bl_world = world_override;
+  }
+
   bNodeTree *ntree = (bl_world->nodetree && bl_world->use_nodes) ?
                          bl_world->nodetree :
                          default_tree.nodetree_get(bl_world);