Circle.java

@RequiredArgsConstructor
public class Circle {

    @Getter
    private final double radius;
    @Getter
    private final Vector3d center;
    @Getter
    private final int shardCount;
    @Getter
    private final double degreeIncrease;
    @Getter
    private Set<CircleShard> shards;

    public Set<CircleShard> tick() {
        if (shards.isEmpty()) {
            this.shards = Sets.newHashSetWithExpectedSize(shardCount);

            double delta = 360.0 / shardCount;
            for (int i = 0; i < shardCount; i++) {
                shards.add(new CircleShard(this, delta * i));
            }
            return shards;
        }

        shards.forEach(CircleShard::tick);

        return shards;
    }

    public static class CircleShard {

        private Circle circle;
        private double index;
        @Getter
        private MuVector3d location;

        public CircleShard(Circle circle, double index) {
            this.circle = circle;
            this.index = index;
            this.location = MuVector3d.of(circle.center);
        }

        public void tick() {
            index += circle.getDegreeIncrease();
            if (index > 360) {
                index -= 360;
            }

            double theta = Math.toRadians(index);
            double x = circle.radius * Math.cos(theta) + circle.center.x();
            double z = circle.radius * Math.sin(theta) + circle.center.z();

            location.set(x, location.y(), z);
        }
    }
}