add mesh class

include/omath/3d_primitives/mesh.hpp

@@ -0,0 +1,97 @@
+//
+// Created by Vladislav on 09.11.2025.
+//
+#pragma once
+#include "omath/linear_algebra/triangle.hpp"
+#include <omath/linear_algebra/mat.hpp>
+#include <omath/linear_algebra/vector3.hpp>
+#include <utility>
+#include <vector>
+
+namespace omath::primitives
+{
+    template<class Mat4X4, class RotationAngles, class MeshTypeTrait, class NumericType = float>
+    class Mesh final
+    {
+        using Vbo = std::vector<Vector3<NumericType>>;
+        using Vao = std::vector<Vector3<std::size_t>>;
+
+    public:
+        Vbo m_vertex_buffer;
+        Vao m_vertex_array_object;
+
+        Mesh(Vbo vbo, Vao vao): m_vertex_buffer(std::move(vbo)), m_vertex_array_object(std::move(vao))
+        {
+
+        }
+        void set_origin(const Vector3<NumericType>& new_origin)
+        {
+            m_origin = new_origin;
+            m_to_world_matrix = std::nullopt;
+        }
+
+        void set_scale(const Vector3<NumericType>& new_scale)
+        {
+            m_scale = new_scale;
+            m_to_world_matrix = std::nullopt;
+        }
+
+        void set_rotation(const RotationAngles& new_rotation_angles)
+        {
+            m_rotation_angles = new_rotation_angles;
+            m_to_world_matrix = std::nullopt;
+        }
+
+        [[nodiscard]]
+        const Vector3<NumericType>& get_origin() const
+        {
+            return m_origin;
+        }
+
+        [[nodiscard]]
+        const Vector3<NumericType>& get_scale() const
+        {
+            return m_scale;
+        }
+
+        [[nodiscard]]
+        const RotationAngles& get_rotation_angles() const
+        {
+            return m_rotation_angles;
+        }
+
+        [[nodiscard]]
+        const Mat4X4& get_to_world_matrix() const
+        {
+            if (m_to_world_matrix)
+                return m_to_world_matrix.value();
+            m_to_world_matrix =
+                    mat_translation(m_origin) * mat_scale(m_scale) * MeshTypeTrait::rotation_matrix(m_rotation_angles);
+
+            return m_to_world_matrix.value();
+        }
+
+        [[nodiscard]]
+        Vector3<float> vertex_to_world_space(const Vector3<float>& vertex) const
+        {
+            auto abs_vec = get_to_world_matrix() * mat_column_from_vector(vertex);
+
+            return {abs_vec.at(0, 0), abs_vec.at(1, 0), abs_vec.at(2, 0)};
+        }
+        [[nodiscard]]
+        Triangle<Vector3<float>> make_face_in_world_space(const Vao::const_iterator index) const
+        {
+            return {vertex_to_world_space(m_vertex_buffer.at(index->x)),
+                    vertex_to_world_space(m_vertex_buffer.at(index->y)),
+                    vertex_to_world_space(m_vertex_buffer.at(index->z))};
+        }
+
+    private:
+        Vector3<NumericType> m_origin;
+        Vector3<NumericType> m_scale;
+
+        RotationAngles m_rotation_angles;
+
+        mutable std::optional<Mat4X4> m_to_world_matrix;
+    };
+} // namespace omath::primitives