Circle 0

circle0.c

shader circle0(
    vector UV = vector(0.5, 0.5, 0.0),
    vector Center = vector(0.5, 0.5, 0.0),
    float Radius = 1.0,
    float Blur = 0.0,
    color Outside = color(1.0, 0.0, 0.0),
    color Inside = 1.0,
    
    output color Color = 0.8,
    output float Fac = 0.5) {

    vector diff = Center - UV;
    float lenSq = dot(diff, diff);
    float eval = 0.25 * Radius * Radius - lenSq;
    float halfBlur = 0.5 * clamp(Blur, 0.0, 1.0);
    Fac = smoothstep(-halfBlur, halfBlur, eval);
    Color = mix(Outside, Inside, Fac);
}