osg 顶点属性

class MVPCallback : public osg::Uniform::Callback
{
 public:
	MVPCallback(osg::Camera* camera) : mCamera(camera)
	{
	}
	virtual void operator()(osg::Uniform* uniform, osg::NodeVisitor* nv)
	{
		osg::Matrix modelView = mCamera->getViewMatrix();
		osg::Matrix projectM  = mCamera->getProjectionMatrix();
		uniform->set(modelView * projectM);
	}

 private:
	osg::Camera* mCamera;
};

osg::Geometry* createLine2(const std::vector<osg::Vec3d>& allPTs, const std::vector<osg::Vec3d>& colors, osg::Camera* camera)
{
	cout << "osg::getGLVersionNumber" << osg::getGLVersionNumber() << endl;

	//传递给shader
	osg::ref_ptr<osg::Vec3Array> a_color = new osg::Vec3Array;

	int nCount = allPTs.size();

	osg::ref_ptr<osg::Geometry> pGeometry = new osg::Geometry();

	osg::ref_ptr<osg::Vec3Array> a_pos = new osg::Vec3Array;

	for (int i = 0; i < allPTs.size(); i++)
	{
		a_pos->push_back(allPTs[i]);
	}

	const int							   kLastIndex = allPTs.size() - 1;
	osg::ref_ptr<osg::ElementBufferObject> ebo		  = new osg::ElementBufferObject;
	osg::ref_ptr<osg::DrawElementsUInt>	indices	= new osg::DrawElementsUInt(osg::PrimitiveSet::LINE_STRIP);

	std::default_random_engine			  eng(time(NULL));
	std::uniform_real_distribution<float> rand(.3, 1.);

	int count = 0;
	for (unsigned int i = 0; i < allPTs.size(); i++)
	{
		if (allPTs[i].x() == -1 && allPTs[i].y() == -1)
		{
			indices->push_back(kLastIndex);
		}
		else
		{
			indices->push_back(i);
		}
		count++;

		a_color->push_back(colors[i]);
	}

	indices->setElementBufferObject(ebo);
	pGeometry->addPrimitiveSet(indices.get());
	pGeometry->setUseVertexBufferObjects(true); 
	osg::StateSet* ss = pGeometry->getOrCreateStateSet();
	ss->setAttributeAndModes(new osg::LineWidth(2), osg::StateAttribute::ON);
	ss->setMode(GL_LIGHTING, osg::StateAttribute::OFF | osg::StateAttribute::PROTECTED);
	ss->setMode(GL_PRIMITIVE_RESTART, osg::StateAttribute::ON);
	ss->setAttributeAndModes(new osg::PrimitiveRestartIndex(kLastIndex), osg::StateAttribute::ON);

	//------------------------osg::Program-----------------------------
	osg::Program* program = new osg::Program;
	program->setName("LINESTRIPE");
	program->addShader(osgDB::readShaderFile(osg::Shader::VERTEX, shader_dir() + "/line_stripe2.vert"));
	program->addShader(osgDB::readShaderFile(osg::Shader::FRAGMENT, shader_dir() + "/line_stripe2.frag"));

	ss->setAttributeAndModes(program, osg::StateAttribute::ON);

	//-----------attribute  addBindAttribLocation
	pGeometry->setVertexArray(a_pos);
	pGeometry->setVertexAttribArray(0, a_pos, osg::Array::BIND_PER_VERTEX);
	pGeometry->setVertexAttribBinding(0, osg::Geometry::BIND_PER_VERTEX);
	program->addBindAttribLocation("a_pos", 0);

	pGeometry->setVertexAttribArray(1, a_color, osg::Array::BIND_PER_VERTEX);
	pGeometry->setVertexAttribBinding(1, osg::Geometry::BIND_PER_VERTEX);
	program->addBindAttribLocation("a_color", 1);

	//-----------------------------------------------uniform
	osg::Uniform* u_MVP(new osg::Uniform(osg::Uniform::FLOAT_MAT4, "u_MVP"));
	u_MVP->setUpdateCallback(new MVPCallback(camera));
	ss->addUniform(u_MVP);

	return pGeometry.release();
}