The Cube / Triangle shown have alpha values on their color of 0.51
The lines have an alpha value of 1.0
You should be able to see the lines behind the cube / triangle.
All planes in the cube are facing outwards so they can get culled properly.
glfwWindowHint(GLFW_SAMPLES, 4); glEnable(GL_MULTISAMPLE); glEnable(GL_DEPTH_TEST); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glAlphaFunc(GL_GREATER, 0.5); glEnable(GL_ALPHA_TEST); glEnable(GL_CULL_FACE);
Source: Windows Questions C++