opengl-psystem/source/shader/fragment.glsl

#version 330 core

in vec4 vColor;
out vec4 FragColor;

void main() {
    // Soft circular point — discard corners to make round dots
    vec2 coord = gl_PointCoord - vec2(0.5);
    if (dot(coord, coord) > 0.25)
        discard;

    FragColor = vColor;
}