// vertex shader


attribute float cameraPosX;
attribute float cameraPosY;
attribute float cameraPosZ;

varying float sphIndex;

void main()
{
    vec3 cartesian;
    vec3 spherical;

    vec3 v = vec3(gl_Vertex);
    vec3 cameraPos;
    cameraPos.x = cameraPosX;
    cameraPos.y = cameraPosY;
    cameraPos.z = cameraPosZ;

    gl_Position = ftransform();

    vec3 cameraDir = normalize(v - cameraPos);

    spherical.x = 1.0;
    spherical.y = acos(cameraDir.z /
                        sqrt(cameraDir.x*cameraDir.x +
                                cameraDir.y*cameraDir.y +
                                cameraDir.z*cameraDir.z));
    spherical.y = spherical.y * 180.0 / 3.14159265;

    spherical.z = atan(spherical.z, spherical.y);
    spherical.z = spherical.z * 180.0 / 3.14159265;


    sphIndex = (spherical.y*180.0 + spherical.z) / (180.0*180.0);
}


// fragment shader

attribute float cameraPosX;
attribute float cameraPosY;
attribute float cameraPosZ;

varying float sphIndex;

void main()
{
    vec3 cartesian;
    vec3 spherical;

    vec3 v = vec3(gl_Vertex);
    vec3 cameraPos;
    cameraPos.x = cameraPosX;
    cameraPos.y = cameraPosY;
    cameraPos.z = cameraPosZ;

    gl_Position = ftransform();

    vec3 cameraDir = normalize(v - cameraPos);

    spherical.x = 1.0;
    spherical.y = acos(cameraDir.z /
                        sqrt(cameraDir.x*cameraDir.x +
                                cameraDir.y*cameraDir.y +
                                cameraDir.z*cameraDir.z));
    spherical.y = spherical.y * 180.0 / 3.14159265;

    spherical.z = atan(spherical.z, spherical.y);
    spherical.z = spherical.z * 180.0 / 3.14159265;


    sphIndex = (spherical.y*180.0 + spherical.z) / (180.0*180.0);
}