Geometry Nodes: Use separate field context for each geometry type

Using the same `GeometryComponentFieldContext` for all situations,
even when only one geometry type is supported is misleading, and mixes
too many different abstraction levels into code that could be simpler.
With the attribute API moved out of geometry components recently,
the "component" system is just getting in the way here.

This commit adds specific field contexts for geometry types: meshes,
curves, point clouds, and instances. There are also separate field input
helper classes, to help reduce boilerplate for fields that only support
specific geometry types.

Another benefit of this change is that it separates geometry components
from fields, which makes it easier to see the purpose of the two concepts,
and how they relate.

Because we want to be able to evaluate a field on just `CurvesGeometry`
rather than the full `Curves` data-block, the generic "geometry context"
had to be changed to avoid using `GeometryComponent`, since there is
no corresponding geometry component type. The resulting void pointer
is ugly, but only turns up in three places in practice. When Apple clang
supports `std::variant`, that could be used instead.

Differential Revision: https://developer.blender.org/D15519

1 files changed, 20 insertions, 20 deletions

diff --git a/source/blender/nodes/geometry/nodes/node_geo_accumulate_field.cc b/source/blender/nodes/geometry/nodes/node_geo_accumulate_field.cc
index 58fbfb5a000..13a9cdc8600 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_accumulate_field.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_accumulate_field.cc
@@ -192,7 +192,7 @@ static void node_gather_link_searches(GatherLinkSearchOpParams &params)
   }
 }
 
-template<typename T> class AccumulateFieldInput final : public GeometryFieldInput {
+template<typename T> class AccumulateFieldInput final : public bke::GeometryFieldInput {
  private:
   Field<T> input_;
   Field<int> group_index_;
@@ -204,7 +204,7 @@ template<typename T> class AccumulateFieldInput final : public GeometryFieldInpu
                        Field<T> input,
                        Field<int> group_index,
                        AccumulationMode accumulation_mode)
-      : GeometryFieldInput(CPPType::get<T>(), "Accumulation"),
+      : bke::GeometryFieldInput(CPPType::get<T>(), "Accumulation"),
         input_(input),
         group_index_(group_index),
         source_domain_(source_domain),
@@ -212,18 +212,18 @@ template<typename T> class AccumulateFieldInput final : public GeometryFieldInpu
   {
   }
 
-  GVArray get_varray_for_context(const GeometryComponent &component,
-                                 const eAttrDomain domain,
-                                 IndexMask UNUSED(mask)) const final
+  GVArray get_varray_for_context(const bke::GeometryFieldContext &context,
+                                 const IndexMask /*mask*/) const final
   {
-    const GeometryComponentFieldContext field_context{component, source_domain_};
-    const int domain_size = component.attribute_domain_size(field_context.domain());
+    const AttributeAccessor attributes = *context.attributes();
+    const int domain_size = attributes.domain_size(source_domain_);
     if (domain_size == 0) {
       return {};
     }
-    const AttributeAccessor attributes = *component.attributes();
 
-    fn::FieldEvaluator evaluator{field_context, domain_size};
+    const bke::GeometryFieldContext source_context{
+        context.geometry(), context.type(), source_domain_};
+    fn::FieldEvaluator evaluator{source_context, domain_size};
     evaluator.add(input_);
     evaluator.add(group_index_);
     evaluator.evaluate();
@@ -266,7 +266,7 @@ template<typename T> class AccumulateFieldInput final : public GeometryFieldInpu
     }
 
     return attributes.adapt_domain<T>(
-        VArray<T>::ForContainer(std::move(accumulations_out)), source_domain_, domain);
+        VArray<T>::ForContainer(std::move(accumulations_out)), source_domain_, context.domain());
   }
 
   uint64_t hash() const override
@@ -287,7 +287,7 @@ template<typename T> class AccumulateFieldInput final : public GeometryFieldInpu
   }
 };
 
-template<typename T> class TotalFieldInput final : public GeometryFieldInput {
+template<typename T> class TotalFieldInput final : public bke::GeometryFieldInput {
  private:
   Field<T> input_;
   Field<int> group_index_;
@@ -295,25 +295,25 @@ template<typename T> class TotalFieldInput final : public GeometryFieldInput {
 
  public:
   TotalFieldInput(const eAttrDomain source_domain, Field<T> input, Field<int> group_index)
-      : GeometryFieldInput(CPPType::get<T>(), "Total Value"),
+      : bke::GeometryFieldInput(CPPType::get<T>(), "Total Value"),
         input_(input),
         group_index_(group_index),
         source_domain_(source_domain)
   {
   }
 
-  GVArray get_varray_for_context(const GeometryComponent &component,
-                                 const eAttrDomain domain,
-                                 IndexMask UNUSED(mask)) const final
+  GVArray get_varray_for_context(const bke::GeometryFieldContext &context,
+                                 IndexMask /*mask*/) const final
   {
-    const GeometryComponentFieldContext field_context{component, source_domain_};
-    const int domain_size = component.attribute_domain_size(field_context.domain());
+    const AttributeAccessor attributes = *context.attributes();
+    const int domain_size = attributes.domain_size(source_domain_);
     if (domain_size == 0) {
       return {};
     }
-    const AttributeAccessor attributes = *component.attributes();
 
-    fn::FieldEvaluator evaluator{field_context, domain_size};
+    const bke::GeometryFieldContext source_context{
+        context.geometry(), context.type(), source_domain_};
+    fn::FieldEvaluator evaluator{source_context, domain_size};
     evaluator.add(input_);
     evaluator.add(group_index_);
     evaluator.evaluate();
@@ -339,7 +339,7 @@ template<typename T> class TotalFieldInput final : public GeometryFieldInput {
     }
 
     return attributes.adapt_domain<T>(
-        VArray<T>::ForContainer(std::move(accumulations_out)), source_domain_, domain);
+        VArray<T>::ForContainer(std::move(accumulations_out)), source_domain_, context.domain());
   }
 
   uint64_t hash() const override