EU7 scenery format and models streaming

scene/eu7/eu7_section.cpp

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+/*
+This Source Code Form is subject to the
+terms of the Mozilla Public License, v.
+2.0. If a copy of the MPL was not
+distributed with this file, You can
+obtain one at
+http://mozilla.org/MPL/2.0/.
+*/
+
+#include "stdafx.h"
+#include "scene/eu7/eu7_section.h"
+
+#include <algorithm>
+#include <cmath>
+
+namespace scene::eu7 {
+
+std::pair<int, int>
+section_row_column( glm::dvec3 const &world_location ) {
+    auto const column {
+        static_cast<int>( std::floor(
+            world_location.x / static_cast<double>( kSectionSizeM ) +
+            kRegionSideSectionCount / 2 ) ) };
+    auto const row {
+        static_cast<int>( std::floor(
+            world_location.z / static_cast<double>( kSectionSizeM ) +
+            kRegionSideSectionCount / 2 ) ) };
+
+    return {
+        std::clamp( row, 0, kRegionSideSectionCount - 1 ),
+        std::clamp( column, 0, kRegionSideSectionCount - 1 ) };
+}
+
+std::size_t
+section_index( glm::dvec3 const &world_location ) {
+    auto const [row, column] { section_row_column( world_location ) };
+    return section_index( row, column );
+}
+
+std::size_t
+section_index( int const row, int const column ) {
+    return (
+        static_cast<std::size_t>( row ) * static_cast<std::size_t>( kRegionSideSectionCount ) +
+        static_cast<std::size_t>( column ) );
+}
+
+} // namespace scene::eu7