I need to draw contour around 2d objects in 3d space. I tried drawing lines around object(+points to fill the gap), but due to line width, some part of it(~50%) was covering object. I tried to use stencil buffer, to eliminate this problem, but I got sth like this(contour is green):

http://goo.gl/OI5uc (sorry I can't post images, due to my reputation)

You can see(where arrow points), that some parts of line are behind object, and some are above. This changes when I move camera, but always there is some part, that is covering it. Here is code, that I use for drawing object:

    glColorMask(1,1,1,1);
    std::list<CObjectOnScene*>::iterator objIter=ptr->objects.begin(),objEnd=ptr->objects.end();
    int countStencilBit=1;
    while(objIter!=objEnd)
    {
        glColorMask(1,1,1,1);
        glStencilFunc(GL_ALWAYS,countStencilBit,countStencilBit);
        glStencilOp(GL_REPLACE,GL_KEEP,GL_REPLACE );
        (*objIter)->DrawYourVertices();

        glStencilFunc(GL_NOTEQUAL,countStencilBit,countStencilBit);
        glStencilOp(GL_KEEP,GL_KEEP,GL_REPLACE);
        (*objIter)->DrawYourBorder();

        ++objIter;
        ++countStencilBit;
    }

I've tried different settings of stencil buffer, but always I was getting sth like that. Here is question: 1.Am I setting stencil buffer wrong?

2. Are there any other simple ways to create contour on such objects?

Thanks in advance.

EDIT:

1. I don't have normals of objects.

2. Object can be concave.

3. I can't use shaders(see below why).