Stereo issue with shader

[Toan Dinh Nguyen]

Hi Alessandro,

I have simple point shaders:

vert:

#version 120

void main()

{

    gl_Position = ftransform();

    gl_FrontColor = gl_Color;

    gl_PointSize = 20.0;

}

frag:

#version 120

void main() {

    N.xy = gl_PointCoord* 2.0 - vec2(1.0);    

    float mag = dot(N.xy, N.xy);

    if (mag > 1.0) discard;   

    gl_FragColor = gl_Color;

}

and a C program that renders some testing points using the shaders. If I enable the line "if (mag > 1.0) discard;", stereo is disabled and I only see normal 3D points! 

This doesn't happen with python code using cyclops module. I am using Omegalib v13. Any ideas/suggestions?

Thanks,

 

[Alessandro Febretti]

If instead of discarding the fragment  you set its alpha to 0 do you get correct stereo?

[Toan Dinh Nguyen]

I get stereo but black pixels outside the circle. I guess unless they are depth sorted setting alpha won't work.

[Alessandro Febretti]

you should be able to make them fully transparent without issues even if  they are not sorted since you aren't really doing any blending.

If you are writing straight OpenGL code, make sure you have

glEnable(GL_BLEND)

somewhere before your draw code