scripts/startup/bl_ui/node_add_menu_geometry.py

@@ -507,6 +507,7 @@ class NODE_MT_category_GEO_TEXT(Menu):
 
     def draw(self, _context):
         layout = self.layout
+        node_add_menu.add_node_type(layout, "FunctionNodeCharacterAtIndex")
         node_add_menu.add_node_type(layout, "GeometryNodeStringJoin")
         node_add_menu.add_node_type(layout, "FunctionNodeReplaceString")
         node_add_menu.add_node_type(layout, "FunctionNodeSliceString")

source/blender/blenkernel/BKE_node.hh

@@ -1319,6 +1319,7 @@ void BKE_nodetree_remove_layer_n(bNodeTree *ntree, Scene *scene, int layer_index
 #define FN_NODE_SEPARATE_TRANSFORM 1236
 #define FN_NODE_INVERT_MATRIX 1237
 #define FN_NODE_TRANSPOSE_MATRIX 1238
+#define FN_NODE_CHARACTER_AT_INDEX 1239
 
 /** \} */
 

source/blender/nodes/NOD_static_types.h

@@ -265,6 +265,7 @@ DefNode(TextureNode,    TEX_NODE_PROC+TEX_DISTNOISE, 0,                  "TEX_DI
 DefNode(FunctionNode, FN_NODE_ALIGN_EULER_TO_VECTOR, 0, "ALIGN_EULER_TO_VECTOR", AlignEulerToVector, "Align Euler to Vector", "")
 DefNode(FunctionNode, FN_NODE_AXIS_ANGLE_TO_ROTATION, 0, "AXIS_ANGLE_TO_ROTATION", AxisAngleToRotation, "Axis Angle to Rotation", "")
 DefNode(FunctionNode, FN_NODE_BOOLEAN_MATH, 0, "BOOLEAN_MATH", BooleanMath, "Boolean Math", "")
+DefNode(FunctionNode, FN_NODE_CHARACTER_AT_INDEX, 0, "CHARACTER_AT_INDEX", CharacterAtIndex, "Character at Index", "Retrieve a specific Unicode character from a string")
 DefNode(FunctionNode, FN_NODE_COMBINE_COLOR, 0, "COMBINE_COLOR", CombineColor, "Combine Color", "")
 DefNode(FunctionNode, FN_NODE_QUATERNION_TO_ROTATION, 0, "QUATERNION_TO_ROTATION", QuaternionToRotation, "Quaternion to Rotation", "")
 DefNode(FunctionNode, FN_NODE_COMBINE_TRANSFORM, 0, "COMBINE_TRANSFORM", CombineTransform, "Combine Transform", "")

source/blender/nodes/function/CMakeLists.txt

@@ -21,6 +21,7 @@ set(SRC
   nodes/node_fn_align_euler_to_vector.cc
   nodes/node_fn_axis_angle_to_rotation.cc
   nodes/node_fn_boolean_math.cc
+  nodes/node_fn_character_at_index.cc
   nodes/node_fn_combine_color.cc
   nodes/node_fn_combine_transform.cc
   nodes/node_fn_compare.cc

source/blender/nodes/function/nodes/node_fn_character_at_index.cc

@@ -0,0 +1,85 @@
+/* SPDX-FileCopyrightText: 2024 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "BLI_string_utf8.h"
+
+#include "node_function_util.hh"
+
+namespace blender::nodes::node_fn_character_at_index_cc {
+
+static void node_declare(NodeDeclarationBuilder &b)
+{
+  b.is_function_node();
+  b.add_input<decl::String>("String");
+  b.add_input<decl::Int>("Index");
+  b.add_output<decl::String>("Character");
+  b.add_output<decl::Int>("Unicode");
+}
+
+class CharacterAtIndexFunction : public mf::MultiFunction {
+ public:
+  CharacterAtIndexFunction()
+  {
+    static mf::Signature signature_;
+    mf::SignatureBuilder builder{"Character at Index", signature_};
+    builder.single_input<std::string>("String");
+    builder.single_input<int>("Index");
+    builder.single_output<std::string>("Character");
+    builder.single_output<int>("Unicode");
+    this->set_signature(&signature_);
+  }
+
+  void call(const IndexMask &mask, mf::Params params, mf::Context /*context*/) const override
+  {
+    const VArray<std::string> strings = params.readonly_single_input<std::string>(0, "String");
+    const VArray<int> indices = params.readonly_single_input<int>(1, "Index");
+    MutableSpan<std::string> characters = params.uninitialized_single_output<std::string>(
+        2, "Character");
+    MutableSpan<int> unicodes = params.uninitialized_single_output<int>(3, "Unicode");
+
+    Vector<char32_t> char_codes;
+    mask.foreach_index([&](const int64_t i) {
+      const std::string string = strings[i];
+      const int index = indices[i];
+
+      size_t len_bytes;
+      const size_t len_chars = BLI_strlen_utf8_ex(string.c_str(), &len_bytes);
+
+      char_codes.resize(len_chars + 1);
+      BLI_str_utf8_as_utf32(char_codes.data(), string.c_str(), char_codes.size());
+
+      if (!char_codes.index_range().contains(index)) {
+        unicodes[i] = -1;
+        new (&characters[i]) std::string();
+        return;
+      }
+
+      char ch_utf8[BLI_UTF8_MAX + 1];
+      const size_t ch_utf8_len = BLI_str_utf8_from_unicode(
+          char_codes[index], ch_utf8, sizeof(ch_utf8) - 1);
+
+      unicodes[i] = char_codes[index];
+      new (&characters[i]) std::string(ch_utf8, ch_utf8_len);
+    });
+  }
+};
+
+static void node_build_multi_function(NodeMultiFunctionBuilder &builder)
+{
+  static CharacterAtIndexFunction slice_fn;
+  builder.set_matching_fn(&slice_fn);
+}
+
+static void node_register()
+{
+  static bNodeType ntype;
+  fn_node_type_base(
+      &ntype, FN_NODE_CHARACTER_AT_INDEX, "Character at Index", NODE_CLASS_CONVERTER);
+  ntype.declare = node_declare;
+  ntype.build_multi_function = node_build_multi_function;
+  nodeRegisterType(&ntype);
+}
+NOD_REGISTER_NODE(node_register)
+
+}  // namespace blender::nodes::node_fn_character_at_index_cc