assimp/code/AssetLib/Obj/ObjExporter.h

/*
Open Asset Import Library (assimp)
----------------------------------------------------------------------

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All rights reserved.

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  copyright notice, this list of conditions and the
  following disclaimer.

* Redistributions in binary form must reproduce the above
  copyright notice, this list of conditions and the
  following disclaimer in the documentation and/or other
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* Neither the name of the assimp team, nor the names of its
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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*/

/** @file ObjExporter.h
 * Declares the exporter class to write a scene to a Collada file
 */
#ifndef AI_OBJEXPORTER_H_INC
#define AI_OBJEXPORTER_H_INC

#include <assimp/types.h>
#include <sstream>
#include <vector>
#include <map>

#include <assimp/Exporter.hpp>

struct aiScene;
struct aiNode;
struct aiMesh;

namespace Assimp {

// ------------------------------------------------------------------------------------------------
/** Helper class to export a given scene to an OBJ file. */
// ------------------------------------------------------------------------------------------------
class ObjExporter {
public:
    /// Constructor for a specific scene to export
    ObjExporter(const char* filename, const aiScene* pScene, bool noMtl=false, const ExportProperties* props = nullptr);
    ~ObjExporter();
    std::string GetMaterialLibName();
    std::string GetMaterialLibFileName();

    /// public string-streams to write all output into
    std::ostringstream mOutput, mOutputMat;

private:
    // intermediate data structures
    struct FaceVertex {
        FaceVertex()
        : vp()
        , vn()
        , vt() {
            // empty
        }

        // one-based, 0 means: 'does not exist'
        unsigned int vp, vn, vt;
    };

    struct Face {
        char kind;
        std::vector<FaceVertex> indices;
    };

    struct MeshInstance {
        std::string name, matname;
        std::vector<Face> faces;
    };

    void WriteHeader(std::ostringstream& out);
    void WriteMaterialFile();
    void WriteGeometryFile(bool noMtl=false, bool merge_identical_vertices = false);
    std::string GetMaterialName(unsigned int index);
    void AddMesh(const aiString& name, const aiMesh* m, const aiMatrix4x4& mat, bool merge_identical_vertices);
    void AddNode(const aiNode* nd, const aiMatrix4x4& mParent, bool merge_identical_vertices);

private:
    std::string filename;
    const aiScene* const pScene;

    struct vertexData {
        aiVector3D vp;
        aiColor3D vc; // OBJ does not support 4D color
        uint32_t index = 0;
    };

    std::vector<aiVector3D> vn, vt;
    std::vector<aiColor4D> vc;
    std::vector<vertexData> vp;
    bool useVc;

    struct vertexDataCompare {
        bool operator() ( const vertexData& a, const vertexData& b ) const {
            // position
            if (a.vp.x < b.vp.x) return true;
            if (a.vp.x > b.vp.x) return false;
            if (a.vp.y < b.vp.y) return true;
            if (a.vp.y > b.vp.y) return false;
            if (a.vp.z < b.vp.z) return true;
            if (a.vp.z > b.vp.z) return false;

            // color
            if (a.vc.r < b.vc.r) return true;
            if (a.vc.r > b.vc.r) return false;
            if (a.vc.g < b.vc.g) return true;
            if (a.vc.g > b.vc.g) return false;
            if (a.vc.b < b.vc.b) return true;
            if (a.vc.b > b.vc.b) return false;
            return a.index < b.index;
        }
    };

    struct aiVectorCompare {
        bool operator() (const aiVector3D& a, const aiVector3D& b) const {
            if(a.x < b.x) return true;
            if(a.x > b.x) return false;
            if(a.y < b.y) return true;
            if(a.y > b.y) return false;
            if(a.z < b.z) return true;
            return false;
        }
    };

    template <class T, class Compare = std::less<T>>
    class indexMap {
        int mNextIndex;
        typedef std::map<T, int, Compare> dataType;
        dataType vecMap;

    public:
        indexMap()
        : mNextIndex(1) {
            // empty
        }

        int getIndex(const T& key) {
            typename dataType::iterator vertIt = vecMap.find(key);
            // vertex already exists, so reference it
            if(vertIt != vecMap.end()){
                return vertIt->second;
            }
            return vecMap[key] = mNextIndex++;
        };

        void getKeys( std::vector<T>& keys ) {
            keys.resize(vecMap.size());
            for(typename dataType::iterator it = vecMap.begin(); it != vecMap.end(); ++it){
                keys[it->second-1] = it->first;
            }
        };
    };

    indexMap<aiVector3D, aiVectorCompare> mVnMap, mVtMap;
    indexMap<vertexData, vertexDataCompare> mVpMap;
    std::vector<MeshInstance> mMeshes;

    // this endl() doesn't flush() the stream
    const std::string endl;
};

}

#endif