Geometry Nodes: support viewing field values in spreadsheet

The viewer node has been expanded to have a field input next to the
geometry input. When both are connected (by ctrl+shift clicking on a node)
the spreadsheet will show the evaluated field on the geometry.

The operator to link to the viewer has become a bit smarter. It automatically
detects if it should link to the geometry or field input. In the future some more
smartness could be added, such as automatically relinking the "right" geometry
when viewing a field.

Internally, there are two major changes:
* Refactor of what happens when ctrl+shift clicking on a node to link to
  a viewer. The behavior of the geometry nodes viewer is a bit more complex
  than that of the compositor viewers. The behavior in compositing nodes
  should not have changed. Any change should be reported as a bug (and then
  we can decide if it's worse than before or if it needs fixing).
*  Evaluation, display and caching of fields in the spreadsheet editor.

Differential Revision: https://developer.blender.org/D12938

1 files changed, 79 insertions, 0 deletions

diff --git a/source/blender/editors/space_spreadsheet/spreadsheet_cache.cc b/source/blender/editors/space_spreadsheet/spreadsheet_cache.cc
new file mode 100644
index 00000000000..2a399e018b6
--- /dev/null
+++ b/source/blender/editors/space_spreadsheet/spreadsheet_cache.cc
@@ -0,0 +1,79 @@
+/*
+ * 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.
+ */
+
+#include "spreadsheet_cache.hh"
+
+namespace blender::ed::spreadsheet {
+
+void SpreadsheetCache::add(std::unique_ptr<Key> key, std::unique_ptr<Value> value)
+{
+  key->is_used = true;
+  cache_map_.add_overwrite(*key, std::move(value));
+  keys_.append(std::move(key));
+}
+
+SpreadsheetCache::Value *SpreadsheetCache::lookup(const Key &key)
+{
+  std::unique_ptr<Value> *value = cache_map_.lookup_ptr(key);
+  if (value == nullptr) {
+    return nullptr;
+  }
+  const Key &stored_cache_key = cache_map_.lookup_key(key);
+  stored_cache_key.is_used = true;
+  return value->get();
+}
+
+SpreadsheetCache::Value &SpreadsheetCache::lookup_or_add(
+    std::unique_ptr<Key> key, FunctionRef<std::unique_ptr<Value>()> create_value)
+{
+  Value *value = this->lookup(*key);
+  if (value != nullptr) {
+    return *value;
+  }
+  std::unique_ptr<Value> new_value = create_value();
+  value = new_value.get();
+  this->add(std::move(key), std::move(new_value));
+  return *value;
+}
+
+void SpreadsheetCache::set_all_unused()
+{
+  for (std::unique_ptr<Key> &key : keys_) {
+    key->is_used = false;
+  }
+}
+
+void SpreadsheetCache::remove_all_unused()
+{
+  /* First remove the keys from the map and free the values. */
+  for (auto it = cache_map_.keys().begin(); it != cache_map_.keys().end(); ++it) {
+    const Key &key = *it;
+    if (!key.is_used) {
+      cache_map_.remove(it);
+    }
+  }
+  /* Then free the keys. */
+  for (int i = 0; i < keys_.size();) {
+    if (keys_[i]->is_used) {
+      i++;
+    }
+    else {
+      keys_.remove_and_reorder(i);
+    }
+  }
+}
+
+}  // namespace blender::ed::spreadsheet