Geometry Nodes: Support for dynamic attributes on curve splines

With this patch you will be able to add and remove attributes from curve
data inside of geometry nodes. The following is currently implemented:
* Adding attributes with any data type to splines or spline points.
* Support for working with multiple splines at the same time.
* Interaction with the three builtin point attributes.
* Resampling attributes in the resample node.

The following is not implemented in this patch:
* Joining attributes when joining splines with the join geometry node.
* Domain interpolation between spline and point domains.
* More efficient ways to call attribute operations once per spline.

Differential Revision: https://developer.blender.org/D11251

1 files changed, 100 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/attribute_access.cc b/source/blender/blenkernel/intern/attribute_access.cc
index c24630c5666..62833e10438 100644
--- a/source/blender/blenkernel/intern/attribute_access.cc
+++ b/source/blender/blenkernel/intern/attribute_access.cc
@@ -45,6 +45,7 @@ using blender::Set;
 using blender::StringRef;
 using blender::StringRefNull;
 using blender::fn::GMutableSpan;
+using blender::fn::GSpan;
 
 namespace blender::bke {
 
@@ -590,6 +591,105 @@ void NamedLegacyCustomDataProvider::foreach_domain(
   callback(domain_);
 }
 
+CustomDataAttributes::CustomDataAttributes()
+{
+  CustomData_reset(&data);
+  size_ = 0;
+}
+
+CustomDataAttributes::~CustomDataAttributes()
+{
+  CustomData_free(&data, size_);
+}
+
+CustomDataAttributes::CustomDataAttributes(const CustomDataAttributes &other)
+{
+  size_ = other.size_;
+  CustomData_copy(&other.data, &data, CD_MASK_ALL, CD_DUPLICATE, size_);
+}
+
+CustomDataAttributes::CustomDataAttributes(CustomDataAttributes &&other)
+{
+  size_ = other.size_;
+  data = other.data;
+  CustomData_reset(&other.data);
+}
+
+std::optional<GSpan> CustomDataAttributes::get_for_read(const StringRef name) const
+{
+  BLI_assert(size_ != 0);
+  for (const CustomDataLayer &layer : Span(data.layers, data.totlayer)) {
+    if (layer.name == name) {
+      const CPPType *cpp_type = custom_data_type_to_cpp_type((CustomDataType)layer.type);
+      BLI_assert(cpp_type != nullptr);
+      return GSpan(*cpp_type, layer.data, size_);
+    }
+  }
+  return {};
+}
+
+std::optional<GMutableSpan> CustomDataAttributes::get_for_write(const StringRef name)
+{
+  BLI_assert(size_ != 0);
+  for (CustomDataLayer &layer : MutableSpan(data.layers, data.totlayer)) {
+    if (layer.name == name) {
+      const CPPType *cpp_type = custom_data_type_to_cpp_type((CustomDataType)layer.type);
+      BLI_assert(cpp_type != nullptr);
+      return GMutableSpan(*cpp_type, layer.data, size_);
+    }
+  }
+  return {};
+}
+
+bool CustomDataAttributes::create(const StringRef name, const CustomDataType data_type)
+{
+  char name_c[MAX_NAME];
+  name.copy(name_c);
+  void *result = CustomData_add_layer_named(&data, data_type, CD_DEFAULT, nullptr, size_, name_c);
+  return result != nullptr;
+}
+
+bool CustomDataAttributes::create_by_move(const blender::StringRef name,
+                                          const CustomDataType data_type,
+                                          void *buffer)
+{
+  char name_c[MAX_NAME];
+  name.copy(name_c);
+  void *result = CustomData_add_layer_named(&data, data_type, CD_ASSIGN, buffer, size_, name_c);
+  return result != nullptr;
+}
+
+bool CustomDataAttributes::remove(const blender::StringRef name)
+{
+  bool result = false;
+  for (const int i : IndexRange(data.totlayer)) {
+    const CustomDataLayer &layer = data.layers[i];
+    if (layer.name == name) {
+      CustomData_free_layer(&data, layer.type, size_, i);
+      result = true;
+    }
+  }
+  return result;
+}
+
+void CustomDataAttributes::reallocate(const int size)
+{
+  size_ = size;
+  CustomData_realloc(&data, size);
+}
+
+bool CustomDataAttributes::foreach_attribute(const AttributeForeachCallback callback,
+                                             const AttributeDomain domain) const
+{
+  for (const CustomDataLayer &layer : Span(data.layers, data.totlayer)) {
+    AttributeMetaData meta_data{domain, (CustomDataType)layer.type};
+    if (!callback(layer.name, meta_data)) {
+      return false;
+    }
+  }
+  return true;
+}
+
 }  // namespace blender::bke
 
 /* -------------------------------------------------------------------- */