osg::ref_ptr＜osg::Image＞ image = osgDB::readImageFile(fileName)； image指针为空

前言

使用《OpenSceneGraph Quick Start Guide》中文版及源码，里面的一个例子TextureMapping，在我本机上运行没有问题，但拷贝到公司电脑，发现总是运行异常，无法读取纹理图片，

调试到136行 image创建出来总是为空，纹理文件是有的，

#include "osgDB/ReadFile"
#include "osg/Geode"
#include "osg/Geometry"
#include "osg/StateSet"
#include "osg/StateAttribute"
#include "osg/Texture2D"
#include "osg/BlendColor"
#include "osg/AlphaFunc"
#include "osg/Notify"
#include "osg/BlendFunc"
#include "osgDB/WriteFile"
#include "osgDB/ReadFile"
#include "osgViewer/Viewer"
#include "osg/Texture1D"
#include "osg/Texture2D"
#include "osg/Texture3D"
#include "osg/Texture2DArray"


//Geometry->Drawable->Node->Object->Referenced
//AlphaFunc->StateAttribute->Object->Referenced
//StateAttributeCallback->Callback->Object->Referenced
//ClearNode->Group->Node->Object->Referenced
//CoordinateSystemNode->Group->Node->Object->Referenced
//Billboard->Geode->Group->Node->Object->Referenced
//Image->BufferData->Object->Referenced
//Texture1D/Texture2D/Texture2DArray/Texture3D->Texture->TextureAttribute->StateAttribute->Object->Referenced

osg::ref_ptr<osg::Node> createGeode()
{
	osg::ref_ptr<osg::Vec3Array> v = new osg::Vec3Array;
    v->push_back(osg::Vec3(0.f, 0.f, 0.f)); // 0
    v->push_back(osg::Vec3(0.f, 0.f, 4.f));
    v->push_back(osg::Vec3(-1.f, 0.f, 0.f));
    v->push_back(osg::Vec3(1.f, 0.f, 0.f)); //3
    v->push_back(osg::Vec3(1.f, 0.f, 4.f));
    v->push_back(osg::Vec3(-1.f, 0.f, 4.f));
    v->push_back(osg::Vec3(0.f, -1.f, 0.f)); //6
    v->push_back(osg::Vec3(0.f, 1.f, 0.f));
    v->push_back(osg::Vec3(0.f, 1.f, 4.f));
    v->push_back(osg::Vec3(0.f, -1.f, 4.f)); //9

    osg::ref_ptr<osg::Vec2Array> tc = new osg::Vec2Array;
    tc->push_back(osg::Vec2(.5f, 0.f));
    tc->push_back(osg::Vec2(.5f, 1.f));
    tc->push_back(osg::Vec2(0.f, 0.f));
    tc->push_back(osg::Vec2(1.f, 0.f));
    tc->push_back(osg::Vec2(1.f, 1.f));
    tc->push_back(osg::Vec2(0.f, 1.f));
    tc->push_back(osg::Vec2(0.f, 0.f));
    tc->push_back(osg::Vec2(1.f, 0.f));
    tc->push_back(osg::Vec2(1.f, 1.f));
    tc->push_back(osg::Vec2(0.f, 1.f));

    osg::ref_ptr<osg::Vec4Array> c = new osg::Vec4Array;
    c->push_back(osg::Vec4(1.f, 1.f, 1.f, 1.f));

    osg::ref_ptr<osg::Group> grp = new osg::Group;
    {
        osg::ref_ptr<osg::Geometry> geom = new osg::Geometry;
        geom->setVertexArray(v.get());
        geom->setTexCoordArray(0, tc.get());
        geom->setColorArray(c.get());
        geom->setColorBinding(osg::Geometry::BIND_OVERALL);

        // -X panal
        GLushort indices[] = { 2, 0, 1, 5 };
        geom->addPrimitiveSet(new osg::DrawElementsUShort(osg::PrimitiveSet::QUADS, 4, indices));

        osg::ref_ptr<osg::Geode> geode = new osg::Geode;
        geode->addDrawable(geom.get());
        grp->addChild(geode.get());
    }
    {
        osg::ref_ptr<osg::Geometry> geom = new osg::Geometry;
        geom->setVertexArray(v.get());
        geom->setTexCoordArray(0, tc.get());
        geom->setColorArray(c.get());
        geom->setColorBinding(osg::Geometry::BIND_OVERALL);

        // +X panal
        GLushort indices[] = { 2, 3, 4, 5 };
        geom->addPrimitiveSet(new osg::DrawElementsUShort(osg::PrimitiveSet::QUADS, 4, indices));
        
        osg::ref_ptr<osg::Geode> geode = new osg::Geode;
        geode->addDrawable(geom.get());
        grp->addChild(geode);
        //grp->addChild(geode.get());
    }
    {
        osg::ref_ptr<osg::Geometry> geom = new osg::Geometry;
        geom->setVertexArray(v.get());
        geom->setTexCoordArray(0, tc.get());
        geom->setColorArray(c.get());
        geom->setColorBinding(osg::Geometry::BIND_OVERALL);

        GLushort indices[] = { 6, 0, 1, 9 };
        geom->addPrimitiveSet(new osg::DrawElementsUShort(osg::PrimitiveSet::QUADS, 4, indices));

        osg::ref_ptr<osg::Geode> geode = new osg::Geode;
        geode->addDrawable(geom.get());
        grp->addChild(geode.get());
    }

    {
        osg::ref_ptr<osg::Geometry> geom = new osg::Geometry;
        geom->setVertexArray(v.get());
        geom->setTexCoordArray(0, tc.get());
        geom->setColorArray(c.get());
        geom->setColorBinding(osg::Geometry::BIND_OVERALL);

        GLushort indices[] = { 0, 7, 8, 1 };
        geom->addPrimitiveSet(new osg::DrawElementsUShort(osg::PrimitiveSet::QUADS, 4, indices));

        osg::ref_ptr<osg::Geode> geode = new osg::Geode;
        geode->addDrawable(geom.get());
        grp->addChild(geode.get());
    }

    return grp.release();
}

osg::ref_ptr <osg::Node> createSceneGraph()
{
    //osg::ref_ptr<osg::Node> node = new osg::Node;
    osg::ref_ptr<osg::Node> node = createGeode();

    //osg::ref_ptr<osg::StateSet> state = new osg::StateSet;
    osg::ref_ptr<osg::StateSet> state = node->getOrCreateStateSet();
    state->setMode(GL_LIGHTING, osg::StateAttribute::OFF | osg::StateAttribute::PROTECTED);
    state->setRenderingHint(osg::StateSet::TRANSPARENT_BIN);

    // Load the texture image
    //   Image courtesy Virtual Terrain Project (http://vterrain.org/)
    std::string fileName("Picea_pungens__blue_spruce15_256.png");
    osg::ref_ptr<osg::Image> image = osgDB::readImageFile(fileName);
    if (!image.valid())
    {
        osg::notify(osg::FATAL) << "Unable to load data file. Exiting." << std::endl;
        return (NULL);
    }

    // Set the image in a Texture2D object
    osg::ref_ptr<osg::Texture2D> tex = new osg::Texture2D;
    tex->setImage(image.get());

    // After creating the OpenGL texture object, release the
    //   internal ref_ptr<Image> (to delete the Image).
    tex->setUnRefImageDataAfterApply(true);
    state->setTextureAttributeAndModes(0, tex.get());

    // Turn on blending
    //osg::BlendFunc* bf = new osg::BlendFunc;
    osg::ref_ptr<osg::BlendFunc> bf = new osg::BlendFunc(osg::BlendFunc::SRC_ALPHA, osg::BlendFunc::ONE_MINUS_SRC_ALPHA);   //有参数不需要括号构造函数
    state->setAttributeAndModes(bf);

    // Turn on alpha testing
    osg::ref_ptr<osg::AlphaFunc> af = new osg::AlphaFunc(osg::AlphaFunc::GREATER, 0.05f);
    state->setAttributeAndModes(af);


    return (node.release());
}

int main(int argc, char** argv)
{
    //osg::ref_ptr<osg::Node> root = new osg::Node;
    osg::ref_ptr<osg::Node> root = createSceneGraph();
    if (!root.valid())
    {
        //std::cout << 
        osg::notify(osg::FATAL) << "Failed in createSceneGraph()." << std::endl;
        return (1);
    }

    std::string out("TextureMapping.osg");
    if (!(osgDB::writeNodeFile(*(root.get()), out)))
    {
        osg::notify(osg::FATAL) << "Failed in osgDB::writeNodeFile()." << std::endl;
        return (1);     
    }

    osg::notify(osg::ALWAYS) << "Successfully wrote \"" << out << "\". Execute \"osgviewer " << out << "\" to view." << std::endl;

	
    osgViewer::Viewer viewer;
    viewer.setSceneData(osgDB::readNodeFile("TextureMapping.osg"));
    return viewer.run();
    
    
    return 0;
}

解决

没有配置环境变量，根据自己机器实际路径添加，我的机器路径如下
1.在系统环境变量中加入：
（1）OSG_FILE_PATH
（2）OSG_NOTIFY_LEVEL

2.在path中加入
（1）E:\osg\OpenSceneGraph_build_vs2019_x64\bin
（2）E:\osg\3rdParty\3rdParty_x64\x64\lib
（3）E:\osg\3rdParty\3rdParty_x64\x64\bin

工程源码下载

源码工程下载