基础图元 Box

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创建一个长方体（Box）

效果图：

步骤：

  1. 申请一个精度

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    osg::ref_ptr<osg::TessellationHints> hints = new osg::TessellationHints;

    hints->setDetailRatio(0.5);

  2. 申请一个Shape（需要赋值精细度）

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    osg::ref_ptr<osg::ShapeDrawable> shape = new osg::ShapeDrawable(new osg::Box(osg::Vec3(0.0, 0.0, 0.0), 1.0, 10.0, 10.0), hints.get());

    //赋值为灰色，半透明
    shape->setColor(osg::Vec4(0.5, 0.5, 0.5, 0.5));

  3. 申请一个材质

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    osg::ref_ptr<osg::Material> material = new osg::Material;

    material->setAmbient(osg::Material::FRONT_AND_BACK, osg::Vec4f(1.0, 1.0, 1.0, 0.5));
    material->setDiffuse(osg::Material::FRONT_AND_BACK, osg::Vec4f(1.0, 1.0, 1.0, 0.5));
    material->setSpecular(osg::Material::FRONT_AND_BACK, osg::Vec4f(1.0, 1.0, 1.0, 0.5));
    material->setShininess(osg::Material::FRONT_AND_BACK, 6.0);

  4. 申请一个纹理和Image

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    osg::ref_ptr<osg::Texture2D> texture2D = new osg::Texture2D;
    osg::ref_ptr<osg::Image> image = new osg::Image;

    image = osgDB::readImageFile("Images/whitemetal_diffuse.jpg");

    if (image.valid()) {
    	texture2D->setImage(image.get());
    }

  5. 申请一个Geode作为函数返回值

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    osg::ref_ptr<osg::Geode> geode = new osg::Geode;

    geode->getOrCreateStateSet()->setAssociatedModes(material.get(), osg::StateAttribute::ON);
    geode->getOrCreateStateSet()->setMode(GL_BLEND, osg::StateAttribute::ON);
    geode->getOrCreateStateSet()->setMode(GL_DEPTH_TEST, osg::StateAttribute::ON);
    geode->getOrCreateStateSet()->setTextureAttributeAndModes(0, texture2D.get(), osg::StateAttribute::ON);

  6. 在geode中绘制shape

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    geode->addDrawable(shape.get());

  7. 将返回的Geode添加到group中

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    group->addChild(CreateBox());

  8. 完整代码

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    #include <osgViewer/Viewer>
    #include <osgDB/ReadFile>
    #include <osgGA/GUIEventAdapter>
    #include <osgViewer/ViewerEventHandlers>
    #include <osg/Geode>
    #include <osg/ShapeDrawable>
    #include <osg/Material>
    #include <osg/StateSet>
    #include <osg/Image>
    #include <osg/Texture2D>
    #include <iostream>
    using namespace std;

    osg::ref_ptr<osg::Geode> CreateBox() {

    	osg::ref_ptr<osg::Geode> geode = new osg::Geode;
    	osg::ref_ptr<osg::TessellationHints> hints = new osg::TessellationHints;
    	osg::ref_ptr<osg::ShapeDrawable> shape = new osg::ShapeDrawable(new osg::Box(osg::Vec3(0.0, 0.0, 0.0), 1.0, 10.0, 10.0), hints.get());
    	osg::ref_ptr<osg::Material> material = new osg::Material;
    	osg::ref_ptr<osg::Texture2D> texture2D = new osg::Texture2D;
    	osg::ref_ptr<osg::Image> image = new osg::Image;

    	hints->setDetailRatio(0.5);

    	shape->setColor(osg::Vec4(0.5, 0.5, 0.5, 0.5));

    	material->setAmbient(osg::Material::FRONT_AND_BACK, osg::Vec4f(1.0, 1.0, 1.0, 0.5));
    	material->setDiffuse(osg::Material::FRONT_AND_BACK, osg::Vec4f(1.0, 1.0, 1.0, 0.5));
    	material->setSpecular(osg::Material::FRONT_AND_BACK, osg::Vec4f(1.0, 1.0, 1.0, 0.5));
    	material->setShininess(osg::Material::FRONT_AND_BACK, 6.0);

    	image = osgDB::readImageFile("Images/whitemetal_diffuse.jpg");
    	if (image.valid()) {
    		texture2D->setImage(image.get());
    	}

    	//set state
    	geode->getOrCreateStateSet()->setAssociatedModes(material.get(), osg::StateAttribute::ON);
    	geode->getOrCreateStateSet()->setMode(GL_BLEND, osg::StateAttribute::ON);
    	geode->getOrCreateStateSet()->setMode(GL_DEPTH_TEST, osg::StateAttribute::ON);
    	geode->getOrCreateStateSet()->setTextureAttributeAndModes(0, texture2D.get(), osg::StateAttribute::ON);
    	geode->addDrawable(shape.get());

    	return geode;
    }

    int main() {

    	osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer;
    	osg::ref_ptr<osg::Group> group = new osg::Group;
    	
    	group->addChild(CreateBox());
    	viewer->setSceneData(group.get());

    	return viewer->run();
    }