assimp/code/AssetLib/STL/STLExporter.cpp

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

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

* Redistributions in binary form must reproduce the above
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  written permission of the assimp team.

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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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*/



#if !defined(ASSIMP_BUILD_NO_EXPORT) && !defined(ASSIMP_BUILD_NO_STL_EXPORTER)

#include "STLExporter.h"
#include <assimp/version.h>
#include <assimp/IOSystem.hpp>
#include <assimp/scene.h>
#include <assimp/Exporter.hpp>
#include <memory>
#include <assimp/Exceptional.h>
#include <assimp/ByteSwapper.h>

using namespace Assimp;

namespace Assimp    {

// ------------------------------------------------------------------------------------------------
// Worker function for exporting a scene to Stereolithograpy. Prototyped and registered in Exporter.cpp
void ExportSceneSTL(const char* pFile,IOSystem* pIOSystem, const aiScene* pScene, const ExportProperties* pProperties )
{
    bool exportPointClouds = pProperties->GetPropertyBool(AI_CONFIG_EXPORT_POINT_CLOUDS);

    // invoke the exporter
    STLExporter exporter(pFile, pScene, exportPointClouds );

    if (exporter.mOutput.fail()) {
        throw DeadlyExportError("output data creation failed. Most likely the file became too large: " + std::string(pFile));
    }
    
    // we're still here - export successfully completed. Write the file.
    std::unique_ptr<IOStream> outfile (pIOSystem->Open(pFile,"wt"));
    if (outfile == nullptr) {
        throw DeadlyExportError("could not open output .stl file: " + std::string(pFile));
    }

    outfile->Write( exporter.mOutput.str().c_str(), static_cast<size_t>(exporter.mOutput.tellp()),1);
}
void ExportSceneSTLBinary(const char* pFile,IOSystem* pIOSystem, const aiScene* pScene, const ExportProperties* pProperties )
{
    bool exportPointClouds = pProperties->GetPropertyBool(AI_CONFIG_EXPORT_POINT_CLOUDS);

    // invoke the exporter
    STLExporter exporter(pFile, pScene, exportPointClouds, true);

    if (exporter.mOutput.fail()) {
        throw DeadlyExportError("output data creation failed. Most likely the file became too large: " + std::string(pFile));
    }
    
    // we're still here - export successfully completed. Write the file.
    std::unique_ptr<IOStream> outfile (pIOSystem->Open(pFile,"wb"));
    if (outfile == nullptr) {
        throw DeadlyExportError("could not open output .stl file: " + std::string(pFile));
    }

    outfile->Write( exporter.mOutput.str().c_str(), static_cast<size_t>(exporter.mOutput.tellp()),1);
}

} // end of namespace Assimp

static const char *SolidToken = "solid";
static const char *EndSolidToken = "endsolid";

// ------------------------------------------------------------------------------------------------
STLExporter::STLExporter(const char* _filename, const aiScene* pScene, bool exportPointClouds, bool binary)
: filename(_filename)
, endl("\n")
{
    // make sure that all formatting happens using the standard, C locale and not the user's current locale
    const std::locale& l = std::locale("C");
    mOutput.imbue(l);
    mOutput.precision(ASSIMP_AI_REAL_TEXT_PRECISION);
    if (binary) {
        char buf[80] = {0} ;
        buf[0] = 'A'; buf[1] = 's'; buf[2] = 's'; buf[3] = 'i'; buf[4] = 'm'; buf[5] = 'p';
        buf[6] = 'S'; buf[7] = 'c'; buf[8] = 'e'; buf[9] = 'n'; buf[10] = 'e';
        mOutput.write(buf, 80);
        unsigned int meshnum = 0;
        for(unsigned int i = 0; i < pScene->mNumMeshes; ++i) {
            for (unsigned int j = 0; j < pScene->mMeshes[i]->mNumFaces; ++j) {
                meshnum++;
            }
        }
        AI_SWAP4(meshnum);
        mOutput.write((char *)&meshnum, 4);

        if (exportPointClouds) {
            throw DeadlyExportError("This functionality is not yet implemented for binary output.");
        }

        for(unsigned int i = 0; i < pScene->mNumMeshes; ++i) {
            WriteMeshBinary(pScene->mMeshes[i]);
        }
    } else {

        // Exporting only point clouds
        if (exportPointClouds) {
            WritePointCloud("Assimp_Pointcloud", pScene );
            return;
        } 

        // Export the assimp mesh 
        const std::string name = "AssimpScene";
        mOutput << SolidToken << " " << name << endl;
        for(unsigned int i = 0; i < pScene->mNumMeshes; ++i) {
            WriteMesh(pScene->mMeshes[ i ]);
        }
        mOutput << EndSolidToken << " " << name << endl;
    }
}

// ------------------------------------------------------------------------------------------------
void STLExporter::WritePointCloud(const std::string &name, const aiScene* pScene) {
    mOutput << " " << SolidToken << " " << name << endl;
    aiVector3D nor;
    mOutput << " facet normal " << nor.x << " " << nor.y << " " << nor.z << endl;
    for (unsigned int i = 0; i < pScene->mNumMeshes; ++i) {
        aiMesh *mesh = pScene->mMeshes[i];
        if (nullptr == mesh) {
            continue;
        }

        for (unsigned int a = 0; a < mesh->mNumVertices; ++a) {
            const aiVector3D& v = mesh->mVertices[a];
            mOutput << "  vertex " << v.x << " " << v.y << " " << v.z << endl;
            mOutput << "  vertex " << v.x << " " << v.y << " " << v.z << endl;
            mOutput << "  vertex " << v.x << " " << v.y << " " << v.z << endl;
        }
    }
    mOutput << EndSolidToken << " " << name << endl;
}

// ------------------------------------------------------------------------------------------------
void STLExporter::WriteMesh(const aiMesh* m)
{
    for (unsigned int i = 0; i < m->mNumFaces; ++i) {
        const aiFace& f = m->mFaces[i];

        // we need per-face normals. We specified aiProcess_GenNormals as pre-requisite for this exporter,
        // but nonetheless we have to expect per-vertex normals.
        aiVector3D nor;
        if (m->mNormals) {
            for(unsigned int a = 0; a < f.mNumIndices; ++a) {
                nor += m->mNormals[f.mIndices[a]];
            }
            nor.NormalizeSafe();
        }
        mOutput << " facet normal " << nor.x << " " << nor.y << " " << nor.z << endl;
        mOutput << "  outer loop" << endl;
        for(unsigned int a = 0; a < f.mNumIndices; ++a) {
            const aiVector3D& v  = m->mVertices[f.mIndices[a]];
            mOutput << "  vertex " << v.x << " " << v.y << " " << v.z << endl;
        }

        mOutput << "  endloop" << endl;
        mOutput << " endfacet" << endl << endl;
    }
}

void STLExporter::WriteMeshBinary(const aiMesh* m)
{
    for (unsigned int i = 0; i < m->mNumFaces; ++i) {
        const aiFace& f = m->mFaces[i];
        // we need per-face normals. We specified aiProcess_GenNormals as pre-requisite for this exporter,
        // but nonetheless we have to expect per-vertex normals.
        aiVector3D nor;
        if (m->mNormals) {
            for(unsigned int a = 0; a < f.mNumIndices; ++a) {
                nor += m->mNormals[f.mIndices[a]];
            }
            nor.Normalize();
        }
        // STL binary files use 4-byte floats. This may possibly cause loss of precision
        // for clients using 8-byte doubles
        float nx = (float) nor.x;
        float ny = (float) nor.y;
        float nz = (float) nor.z;
        AI_SWAP4(nx); AI_SWAP4(ny); AI_SWAP4(nz);
        mOutput.write((char *)&nx, 4); mOutput.write((char *)&ny, 4); mOutput.write((char *)&nz, 4);
        for(unsigned int a = 0; a < f.mNumIndices; ++a) {
            const aiVector3D& v  = m->mVertices[f.mIndices[a]];
            float vx = (float) v.x, vy = (float) v.y, vz = (float) v.z;
            AI_SWAP4(vx); AI_SWAP4(vy); AI_SWAP4(vz);
            mOutput.write((char *)&vx, 4); mOutput.write((char *)&vy, 4); mOutput.write((char *)&vz, 4);
        }
        char dummy[2] = {0};
        mOutput.write(dummy, 2);
    }
}

#endif