Geometry Nodes: Node error messages

This patch adds icons to the right side of nodes when they encounter a
a problem. When hovered, a tooltip displays describing the encountered
while evaluating the node.

Some examples are: attribute doesn't exist, mesh has no faces,
incorrect attribute type, etc. Exposing more messages to the system
will be an ongoing process. Multiple warnings per node are supported.

The system is implemented somewhat generically so that the basic
structure can also be used to store more information from evaluation
for the interface, like a list of available attributes.

Currently the messages are just button tooltips. They could be styled
differently in the future. Another limitation is that every instance of
a node group in a parent node tree will have the same error messages,
the "evaluation context" used to decide when to display the tooltips
must be extended to support node tree paths.

Differential Revision: https://developer.blender.org/D10290

1 files changed, 95 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_node_ui_storage.hh b/source/blender/blenkernel/BKE_node_ui_storage.hh
new file mode 100644
index 00000000000..0b8ef60a603
--- /dev/null
+++ b/source/blender/blenkernel/BKE_node_ui_storage.hh
@@ -0,0 +1,95 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#pragma once
+
+#include "BLI_hash.hh"
+#include "BLI_map.hh"
+#include "BLI_session_uuid.h"
+
+#include "DNA_ID.h"
+#include "DNA_modifier_types.h"
+#include "DNA_session_uuid_types.h"
+
+struct bNode;
+struct bNodeTree;
+struct Object;
+struct ModifierData;
+
+using blender::Map;
+
+/**
+ * Contains the context necessary to determine when to display settings for a certain node tree
+ * that may be used for multiple modifiers and objects. The object name and modifier session UUID
+ * are used instead of pointers because they are re-allocated between evaluations.
+ *
+ * \note This does not yet handle the context of nested node trees.
+ */
+class NodeTreeEvaluationContext {
+ private:
+  std::string object_name_;
+  SessionUUID modifier_session_uuid_;
+
+ public:
+  NodeTreeEvaluationContext(const Object &object, const ModifierData &modifier)
+  {
+    object_name_ = reinterpret_cast<const ID &>(object).name;
+    modifier_session_uuid_ = modifier.session_uuid;
+  }
+
+  uint64_t hash() const
+  {
+    const uint64_t hash1 = blender::DefaultHash<std::string>{}(object_name_);
+    const uint64_t hash2 = BLI_session_uuid_hash_uint64(&modifier_session_uuid_);
+    return hash1 ^ (hash2 * 33); /* Copied from DefaultHash for std::pair. */
+  }
+
+  bool operator==(const NodeTreeEvaluationContext &other) const
+  {
+    return other.object_name_ == object_name_ &&
+           BLI_session_uuid_is_equal(&other.modifier_session_uuid_, &modifier_session_uuid_);
+  }
+};
+
+enum class NodeWarningType {
+  Error,
+  Warning,
+  Info,
+};
+
+struct NodeWarning {
+  NodeWarningType type;
+  std::string message;
+};
+
+struct NodeUIStorage {
+  blender::Vector<NodeWarning> warnings;
+};
+
+struct NodeTreeUIStorage {
+  Map<NodeTreeEvaluationContext, Map<std::string, NodeUIStorage>> context_map;
+};
+
+void BKE_nodetree_ui_storage_free_for_context(bNodeTree &ntree,
+                                              const NodeTreeEvaluationContext &context);
+
+void BKE_nodetree_ui_storage_ensure(bNodeTree &ntree);
+
+void BKE_nodetree_error_message_add(bNodeTree &ntree,
+                                    const NodeTreeEvaluationContext &context,
+                                    const bNode &node,
+                                    const NodeWarningType type,
+                                    std::string message);