Untitled

#version 330

uniform mat4 projectionMatrix;
uniform float sphereRadius;

in vec3 fPosition;

void main()
{
    vec3 Normal;
    // Get the coordinates of the fragment
    Normal.xy = gl_PointCoord * 2.0 - vec2(1.0);
    // Is the fragment inside the unit circle?
    float r2 = dot(Normal.xy,Normal.xy);
    if(r2 > 1.0) discard;
    // Compute the depth on a unit sphere
    Normal.z = -sqrt(1.0 - r2);

    // View-space depth
    vec4 fPos = vec4(fPosition - sphereRadius*Normal, 1.0);
    vec4 clipPos = projectionMatrix * fPos;
    gl_FragDepth = clipPos.z / clipPos.w;

    //far * near / (far * -ndc.z + far + near * ndc.z)
}