Geometry Nodes: String manipulation nodes

This patch adds four new nodes to a new "Text" category:
 - String Length: Outputs length of a string
 - String Substring: Outputs part of a string
 - Value to String: Converts a value to a string
 - String Join: Concatenates multiple strings with a delimiter

The initial use case of these nodes is the upcoming string to curve
node. However, they could also be used to calculate dynamic attribute
names, or with string attributes in the future.

Differential Revision: https://developer.blender.org/D12532

3 files changed, 154 insertions, 0 deletions

diff --git a/source/blender/nodes/function/nodes/node_fn_string_length.cc b/source/blender/nodes/function/nodes/node_fn_string_length.cc
new file mode 100644
index 00000000000..a0f85dfd2bf
--- /dev/null
+++ b/source/blender/nodes/function/nodes/node_fn_string_length.cc
@@ -0,0 +1,49 @@
+/*
+ * 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 "BLI_string_utf8.h"
+
+#include <iomanip>
+
+#include "node_function_util.hh"
+
+namespace blender::nodes {
+
+static void fn_node_string_length_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::String>("String");
+  b.add_output<decl::Int>("Length");
+};
+
+}  // namespace blender::nodes
+
+static void fn_node_string_length_build_multi_function(
+    blender::nodes::NodeMultiFunctionBuilder &builder)
+{
+  static blender::fn::CustomMF_SI_SO<std::string, int> str_len_fn{
+      "String Length", [](const std::string &a) { return BLI_strlen_utf8(a.c_str()); }};
+  builder.set_matching_fn(&str_len_fn);
+}
+
+void register_node_type_fn_string_length()
+{
+  static bNodeType ntype;
+
+  fn_node_type_base(&ntype, FN_NODE_STRING_LENGTH, "String Length", NODE_CLASS_CONVERTER, 0);
+  ntype.declare = blender::nodes::fn_node_string_length_declare;
+  ntype.build_multi_function = fn_node_string_length_build_multi_function;
+  nodeRegisterType(&ntype);
+}
diff --git a/source/blender/nodes/function/nodes/node_fn_string_substring.cc b/source/blender/nodes/function/nodes/node_fn_string_substring.cc
new file mode 100644
index 00000000000..55a01093ae9
--- /dev/null
+++ b/source/blender/nodes/function/nodes/node_fn_string_substring.cc
@@ -0,0 +1,54 @@
+/*
+ * 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 "BLI_string_utf8.h"
+
+#include "node_function_util.hh"
+
+namespace blender::nodes {
+
+static void fn_node_string_substring_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::String>("String");
+  b.add_input<decl::Int>("Position");
+  b.add_input<decl::Int>("Length").min(0);
+  b.add_output<decl::String>("String");
+};
+
+}  // namespace blender::nodes
+
+static void fn_node_string_substring_build_multi_function(
+    blender::nodes::NodeMultiFunctionBuilder &builder)
+{
+  static blender::fn::CustomMF_SI_SI_SI_SO<std::string, int, int, std::string> substring_fn{
+      "Substring", [](const std::string &str, int a, int b) {
+        const int len = BLI_strlen_utf8(str.c_str());
+        const int start = BLI_str_utf8_offset_from_index(str.c_str(), std::clamp(a, 0, len));
+        const int end = BLI_str_utf8_offset_from_index(str.c_str(), std::clamp(a + b, 0, len));
+        return str.substr(start, std::max<int>(end - start, 0));
+      }};
+  builder.set_matching_fn(&substring_fn);
+}
+
+void register_node_type_fn_string_substring()
+{
+  static bNodeType ntype;
+
+  fn_node_type_base(&ntype, FN_NODE_STRING_SUBSTRING, "String Substring", NODE_CLASS_CONVERTER, 0);
+  ntype.declare = blender::nodes::fn_node_string_substring_declare;
+  ntype.build_multi_function = fn_node_string_substring_build_multi_function;
+  nodeRegisterType(&ntype);
+}
diff --git a/source/blender/nodes/function/nodes/node_fn_value_to_string.cc b/source/blender/nodes/function/nodes/node_fn_value_to_string.cc
new file mode 100644
index 00000000000..c1e6373cb6d
--- /dev/null
+++ b/source/blender/nodes/function/nodes/node_fn_value_to_string.cc
@@ -0,0 +1,51 @@
+/*
+ * 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 "node_function_util.hh"
+#include <iomanip>
+
+namespace blender::nodes {
+
+static void fn_node_value_to_string_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::Float>("Value");
+  b.add_input<decl::Int>("Decimals").min(0);
+  b.add_output<decl::String>("String");
+};
+
+}  // namespace blender::nodes
+
+static void fn_node_value_to_string_build_multi_function(
+    blender::nodes::NodeMultiFunctionBuilder &builder)
+{
+  static blender::fn::CustomMF_SI_SI_SO<float, int, std::string> to_str_fn{
+      "Value To String", [](float a, int b) {
+        std::stringstream stream;
+        stream << std::fixed << std::setprecision(std::max(0, b)) << a;
+        return stream.str();
+      }};
+  builder.set_matching_fn(&to_str_fn);
+}
+
+void register_node_type_fn_value_to_string()
+{
+  static bNodeType ntype;
+
+  fn_node_type_base(&ntype, FN_NODE_VALUE_TO_STRING, "Value to String", NODE_CLASS_CONVERTER, 0);
+  ntype.declare = blender::nodes::fn_node_value_to_string_declare;
+  ntype.build_multi_function = fn_node_value_to_string_build_multi_function;
+  nodeRegisterType(&ntype);
+}