OSG世界坐标转屏幕坐标

#define M(row,col) m[col * 4 + row]

void Transform_Point(double out[4], const double m[16], const double in[4]){
out[0] = M(0, 0) * in[0] + M(0, 1) * in[1] + M(0, 2) * in[2] + M(0, 3) * in[3];
out[1] = M(1, 0) * in[0] + M(1, 1) * in[1] + M(1, 2) * in[2] + M(1, 3) * in[3];
out[2] = M(2, 0) * in[0] + M(2, 1) * in[1] + M(2, 2) * in[2] + M(2, 3) * in[3];
out[3] = M(3, 0) * in[0] + M(3, 1) * in[1] + M(3, 2) * in[2] + M(3, 3) * in[3];
}

osg::Vec3d WorldToScreen(osgViewer::View* view,osg::Vec3 worldpoint){
double in[4], out[4];

in[0] = worldpoint._v[0];
in[1] = worldpoint._v[1];
in[2] = worldpoint._v[2];
in[3] = 1.0;
//获得当前的投影矩阵和模型视图矩阵

osg::Matrix projectMatrix= view->getCamera()->getProjectionMatrix();
osg::Matrix viewprojectMatrix = view->getCamera()->getViewMatrix();
//下面计算 模型视图矩阵 * 投影矩阵 * 视口窗口变换矩阵
double modelViewMatrix[16];
memcpy(modelViewMatrix,viewprojectMatrix.ptr(),sizeof(GLdouble) * 16);
Transform_Point(out, modelViewMatrix, in);

double myprojectMatrix[16];
memcpy(myprojectMatrix,projectMatrix.ptr(),sizeof(GLdouble) * 16);

Transform_Point(in, myprojectMatrix, out);

if(int(in[3] * 100000) == 0){
return osg::Vec3d(0,0,0);
}

in[0] /= in[3];
in[1] /= in[3];
in[2] /= in[3];

int viewPort[4];
osg::Viewport* myviewPort = view->getCamera()->getViewport();
viewPort[0] = 0;
viewPort[1] = 0;
viewPort[2] = mConfigure->GetScreenWidthPixel(); //横向象素点
viewPort[3] = mConfigure->GetScreenHeightPixel();//纵向象素点
//计算 三维点在屏幕上的二维投影点
osg::Vec3d sceenPoint;
sceenPoint._v[0] = (int)(viewPort[0] + (1 + in[0]) * viewPort[2] / 2 + 0.5);
sceenPoint._v[1] = (int)(viewPort[1] + (1 + in[1]) * viewPort[3] / 2 + 0.5);
sceenPoint._v[2] = 0;
return sceenPoint;
}