From 9d3452bea402af5964a26658b2a20d73479f50eb Mon Sep 17 00:00:00 2001
From: Plamen Dragiyski <plamen@dragiyski.org>
Date: Wed, 12 Nov 2025 02:11:15 +0200
Subject: [PATCH] feature: compile index-based coordinate storage

The storage contains coordinates based on their ndims: 1D, 2D or 3D.
---
 src/compile.hpp | 31 +++++++++++++++++++++++++
 src/main.cpp    | 62 +++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 89 insertions(+), 4 deletions(-)
 create mode 100644 src/compile.hpp

diff --git a/src/compile.hpp b/src/compile.hpp
new file mode 100644
index 0000000..1682311
--- /dev/null
+++ b/src/compile.hpp
@@ -0,0 +1,31 @@
+#include <array>
+#include <map>
+#include <set>
+#include <tuple>
+#include <utility>
+#include <vector>
+
+#include "parse.hpp"
+
+namespace wavefront {
+    template<typename IndexType, template<typename, typename...> typename ContainerType, typename ... Args>
+    using coordinate_index_storage_t = std::tuple<
+        std::monostate,
+        ContainerType<IndexType, Args...>,
+        ContainerType<std::array<IndexType, 2>, Args...>,
+        ContainerType<std::array<IndexType, 3>, Args...>
+    >;
+
+    template<typename IndexType, std::size_t NumDims>
+    void append_coordinate_map_to_storage(
+        coordinate_index_storage_t<IndexType, std::set> &target,
+        const std::map<
+            file_line_t,
+            typename std::tuple_element_t<NumDims, std::decay_t<decltype(target)>>::value_type
+        > &source
+    ) {
+        for (const auto &[line_number, coordinates] : source) {
+            std::get<NumDims>(target).emplace(coordinates);
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/main.cpp b/src/main.cpp
index f3531a9..e89bc8d 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -12,8 +12,9 @@
 #include <stdexcept>
 #include <variant>
 
-#include "parse.hpp"
 #include "scan.hpp"
+#include "parse.hpp"
+#include "compile.hpp"
 #include "settings.hpp"
 
 static void usage(const char* prog) {
@@ -37,6 +38,17 @@ static void usage(const char* prog) {
         return return_value; \
     }
 
+template<typename TargetType, typename SourceType, typename Function, std::size_t... Index>
+inline void foreach_tuple_element(TargetType &target_tuple, const SourceType &source_tuple, Function function, std::index_sequence<Index...>) {
+    static_assert(std::tuple_size_v<TargetType> == std::tuple_size_v<SourceType>);
+    ((
+        function(
+            std::get<Index>(target_tuple),
+            std::get<Index>(source_tuple)
+        )
+    ), ...);
+}
+
 int main(int argc, char** argv) {
     using namespace wavefront;
 
@@ -118,6 +130,9 @@ int main(int argc, char** argv) {
 
     Settings settings = settings_builder.build();
 
+    using FloatType = float;
+    using IndexType = std::size_t;
+
     CATCH_AND_RETURN(scan_data, wavefront::scan_error, 1, wavefront::scan(
         settings.input(),
         settings.selected_objects(),
@@ -137,13 +152,52 @@ int main(int argc, char** argv) {
     std::cerr << "Selected " << face_data.index_normal_set.size() << " vertex normals" << std::endl;
     std::cerr << "Selected " << face_data.index_texcoord_set.size() << " vertex texture coordinates" << std::endl;
 
-    CATCH_AND_RETURN(coordinate_data, wavefront::parse_error, 1, wavefront::parse_coordinate_data<float>(scan_data, face_data));
+    CATCH_AND_RETURN(coordinate_data, wavefront::parse_error, 1, wavefront::parse_coordinate_data<FloatType>(scan_data, face_data));
 
-    auto number_list = create_number_list<float>(coordinate_data);
+    auto number_list = create_number_list<FloatType>(coordinate_data);
 
     std::cerr << "Generated number list with " << number_list.size() << " values" << std::endl;
 
-    auto coordinate_index_data = create_coordinate_index<float, std::size_t>(coordinate_data, number_list);
+    auto coordinate_index_data = create_coordinate_index<FloatType, IndexType>(coordinate_data, number_list);
+
+    coordinate_index_storage_t<IndexType, std::set> ndim_coordinate_storage_set;
+    append_coordinate_map_to_storage<IndexType, 3>(ndim_coordinate_storage_set, coordinate_index_data.position_coordinates);
+    append_coordinate_map_to_storage<IndexType, 3>(ndim_coordinate_storage_set, coordinate_index_data.normal_coordinates);
+
+    std::visit([&](const auto &texture_coordinates) {
+        if constexpr (std::ranges::range<std::decay_t<decltype(texture_coordinates)>>) {
+            if constexpr (std::ranges::range<typename std::decay_t<decltype(texture_coordinates)>::mapped_type>) {
+                append_coordinate_map_to_storage<
+                    IndexType,
+                    std::tuple_size_v<typename std::decay_t<decltype(texture_coordinates)>::mapped_type>
+                >(ndim_coordinate_storage_set, texture_coordinates);
+            } else {
+                append_coordinate_map_to_storage<
+                    IndexType,
+                    1
+                >(ndim_coordinate_storage_set, texture_coordinates);
+            }
+        }
+    }, coordinate_index_data.texture_coordinates);
+
+    coordinate_index_storage_t<IndexType, std::vector> ndim_coordinate_storage;
+
+    foreach_tuple_element(
+        ndim_coordinate_storage,
+        ndim_coordinate_storage_set,
+        [&](
+            auto &target,
+            const auto &source
+        ) {
+            target.reserve(source.size());
+            std::copy(
+                source.begin(),
+                source.end(),
+                std::back_inserter(target)
+            );
+        },
+        std::index_sequence<1, 2, 3>{}
+    );
 
     // Form coordinate_list_data : std::vector variant of coordinate_index_data. Internally, it creates std::set initially, stores everything in the set and then convert to vector.
     // Then we can form coordinate_line_mapping : std::map<file_line_t, std::size_t> pointing for each entry to entry in coordinate_list_data.