AxisSwapMesh.hpp

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//
//  CeresEngine - A game development framework
//
//  Created by Rogiel Sulzbach.
//  Copyright (c) 2018-2022 Rogiel Sulzbach. All rights reserved.
//
 
#pragma once
 
#include "Axis.hpp"
#include "TransformMesh.hpp"
#include "Triangle.hpp"
 
namespace CeresEngine::MeshGenerator {
 
    template<typename Mesh> class AxisSwapMesh {
    private:
        using Impl = TransformMesh<Mesh>;
        Impl mTransformMesh;
 
    public:
        class Triangles {
        public:
            [[nodiscard]] Triangle generate() const {
                Triangle triangle = mTriangles.generate();
                if(mMesh->mFlip)
                    std::swap(triangle.vertices[0], triangle.vertices[2]);
                return triangle;
            }
 
            [[nodiscard]] bool done() const noexcept { return mTriangles.done(); }
            void next() { mTriangles.next(); }
 
        private:
            const AxisSwapMesh* mMesh;
 
            typename TriangleGeneratorType<TransformMesh<Mesh>>::Type mTriangles;
 
            Triangles(const AxisSwapMesh& mesh) : mMesh{&mesh}, mTriangles{mesh.mTransformMesh.triangles()} {}
 
            friend class AxisSwapMesh;
        };
 
        AxisSwapMesh(Mesh mesh, Axis x, Axis y, Axis z)
                : mTransformMesh{std::move(mesh),
                      [x, y, z](MeshVertex& vertex) {
                          vertex.position = Vector3{vertex.position[static_cast<int>(x)], vertex.position[static_cast<int>(y)],
                              vertex.position[static_cast<int>(z)]};
                          vertex.normal = Vector3{vertex.normal[static_cast<int>(x)], vertex.normal[static_cast<int>(y)], vertex.normal[static_cast<int>(z)]};
                      }},
                  mFlip{true} {
            if(x != Axis::X) {
                mFlip = !mFlip;
            }
 
            if(y != Axis::Y) {
                mFlip = !mFlip;
            }
 
            if(z != Axis::Z) {
                mFlip = !mFlip;
            }
        }
 
        [[nodiscard]] Triangles triangles() const noexcept { return {*this}; }
 
        using Vertices = typename Impl::Vertices;
        [[nodiscard]] Vertices vertices() const noexcept { return mTransformMesh.vertices(); }
 
    private:
        bool mFlip;
    };
 
    template<typename Mesh> AxisSwapMesh<Mesh> axisSwapMesh(Mesh mesh, Axis x, Axis y, Axis z) { return AxisSwapMesh<Mesh>{std::move(mesh), x, y, z}; }
 
} // namespace CeresEngine::MeshGenerator