line vertex is too thick (no matter what the width is)

Question

I am drawing 3 lines with a function I made (simplified, working example):

template<class... Args> inline void DrawPoly(float width , int color, Args... args)
{
    glLineWidth(width); 
    ofSetHexColor(color);
    glBegin(GL_LINES);
    std::array<ofPoint, sizeof...(args)> list = {args...};
    for(size_t i = 1, j = list.size(); i < j; ++i)
    {
        glVertex3f(list[i-1].x, list[i-1].y, list[i-1].z);
        glVertex3f(list[i].x, list[i].y, list[i].z);
    }
    glEnd();
}

It does it's job nicely, but I can't get good 1 pixel sized lines. No matter what I set the width too.

This is how I call the function:

DrawPoly(0.001,0x77777777,ofPoint(150,150),ofPoint(200,150),ofPoint(200,200),ofPoint(150,200));

and this is the result (and no matter how low I set the width!):

I don't understand why this happens, I'm trying to switch from directX and the equivalent code gives the result I need:

How can I fix this? This happens to all my line/poly shape code! :(

Answer 1

Most likely you're rendering on a fullscreen antialiasing capable framebuffer (multisampling) and not hitting the exact pixel centers. So your line actually covers into two rows/columns of pixels giving that effect. Try what happens if you forcefully disable antialiasing (using the GPU driver control panel).