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1 files changed, 78 insertions, 0 deletions

diff --git a/src/wireframe-mesh.hpp b/src/wireframe-mesh.hpp
new file mode 100644
index 00000000..c31ee1d0
--- /dev/null
+++ b/src/wireframe-mesh.hpp
@@ -0,0 +1,78 @@
+#pragma once
+
+#include "tile-atlas.hpp"
+#include "tile-defs.hpp"
+#include <array>
+#include <utility>
+#include <Corrade/Containers/ArrayViewStl.h>
+#include <Magnum/Math/Vector2.h>
+#include <Magnum/GL/Buffer.h>
+#include <Magnum/GL/Mesh.h>
+#include "Magnum/GL/RectangleTexture.h"
+
+namespace Magnum::Examples {
+
+struct tile_shader;
+
+namespace wireframe_traits {
+
+template<typename T>
+concept traits = requires (const T& x) {
+    {T::num_vertices} -> std::convertible_to<std::size_t>;
+    {T::num_indices} -> std::convertible_to<std::size_t>;
+    {x.primitive} -> std::convertible_to<GL::MeshPrimitive>;
+    {x.make_vertex_positions_array() } -> std::same_as<std::array<Vector3, T::num_vertices>>;
+    {x.make_index_array() } -> std::same_as<std::array<UnsignedShort, T::num_indices>>;
+};
+
+
+struct null final
+{
+    static constexpr auto primitive = GL::MeshPrimitive::Triangles;
+    static constexpr std::size_t num_vertices = 0, num_indices = 0;
+    static GL::RectangleTexture make_constant_texture();
+    static std::array<Vector3, 0> make_vertex_positions_array() { return {}; }
+    static std::array<UnsignedShort, 0> make_index_array() { return {}; }
+};
+
+struct quad final
+{
+    quad(Vector3 center, Vector2 size = {TILE_SIZE[0], TILE_SIZE[1]});
+    constexpr quad() = default;
+
+    static constexpr std::size_t num_vertices = 4;
+    static constexpr std::size_t num_indices = 0;
+    static constexpr GL::MeshPrimitive primitive = GL::MeshPrimitive::LineLoop;
+
+    using vertex_array = std::array<Vector3, num_vertices>;
+    using index_array = std::array<UnsignedShort, num_indices>;
+
+    vertex_array make_vertex_positions_array() const;
+    static index_array make_index_array() { return {}; }
+
+private:
+    Vector3 center = {};
+    Vector2 size = { TILE_SIZE[0], TILE_SIZE[1] };
+};
+
+} // namespace wireframe_traits
+
+
+template<wireframe_traits::traits T>
+struct wireframe_mesh final
+{
+    wireframe_mesh();
+    void draw(tile_shader& shader, T traits);
+
+private:
+    GL::Buffer _positions_buffer{},
+               _texcoords_buffer{std::array<Vector2, T::num_vertices>{}},
+               _index_buffer{T::num_indices == 0 ? GL::Buffer{NoCreate} : GL::Buffer{}};
+    GL::RectangleTexture _texture = wireframe_traits::null::make_constant_texture();
+    GL::Mesh _mesh;
+};
+
+extern template struct wireframe_mesh<wireframe_traits::null>;
+extern template struct wireframe_mesh<wireframe_traits::quad>;
+
+} // namespace Magnum::Examples