Stencil buffer problem

OpenGL OpenGL: Basic Coding
1

Just trying to use the stencil buffer for the first and and my first test worked straight away. To write to the stencil I used


     // Clear the stencil to 0
    glEnable(GL_STENCIL_TEST);
    glClearStencil(0);
    glClear(GL_STENCIL_BUFFER_BIT);
    // INCRease stencil to non-zero when draw
    glStencilOp(GL_INCR, GL_INCR, GL_INCR);
    // NEVER pass so nothing appears on screen
    glStencilFunc(GL_NEVER, 0x0, 0x0);

    // Single glDrawArrays call to draw the stencil shape I want.

    glDisable(GL_STENCIL_TEST);
    glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);

Then to render my image


        glEnable(GL_STENCIL_TEST);
        // Only show parts which where stencil is ZERO
        glStencilFunc(GL_EQUAL, 0, 0xffffffff);
        glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);

and I got no image for the parts where I drew to the stencil.

However, I then changed the GL_EQUAL to GL_NOTEQUAL and my entire image was visible. I thought it would invert the result i.e. I’d only see the image for where I drew to the stencil.

I’m obviously not unstanding something fundemental about the stencil test.

2

Solved. Like an idiot I’d put the call to turn off the stencil test in the wrong place. What I don’t understand though is why it worked at all.