Bullet-Hell Tool (C#) - Rotate Half-Circle of Objects / Projectiles Towards Directional Vector2.

Questions & Answers
1

_Greetings
Greetings. I am working on c# script for a ‘bullet-hell’ tool and I have gotten stuck trying to produce a crescent / half-circle of objects - that turns toward the traveling direction. The scripts spawn a perfect half-circle every time and keep them there, no matter object-amount. No problem there.

_Question
What I am trying to achieve is for the half-circle to point towards the travel-direction of the centerObject. This travel direction is described via a Vector2 between (1,1) and (-1,-1). How can I use this vector to turn the half-circle in the direction of travel?

164217-example.png
There are multiple instances of InitializeOrbit, each responsible for its own half-circle and with a corresponding move direction Vector2.

_Code
In the first script, the ‘theta’ is first calculated, whereafter the objects are spawned.

public void InitializeOrbit()
{
    for (int i = 0; i < numberOfOrbits; i++)
    {
         float theta = (1 * Mathf.PI / numberOfOrbits) * i;
         Instantiate(OrbitPrefab, orbitLocation, transform.rotation);
    }
}

And in the second, the theta is used to calculate the position of the individual objects.

public void OrbitSource ()
{
    Vector2 offset = new Vector2(Mathf.Sin(theta) * orbitRadius, Mathf.Cos(theta) * orbitRadius);
    transform.position = (Vector2)centerTransform.position + offset;
}

I hope I have provided proper information, thanks in advance.

2

I managed to write a solution myself. I lot of information has been found in this stackoverflow which was a great help. Here’s the script:

public void InitializeOrbitProjectiles()
{
    Vector3 posA = new Vector3(projectile.direction.y, -projectile.direction.x) + transform.position;
    Vector3 posB = new Vector3(-projectile.direction.y, projectile.direction.x) + transform.position;

    var centerDirection = Quaternion.LookRotation((posB - posA).normalized);
    float directionAngle = Angle(projectile.direction);

    for (int i = 0; i < projectile.numberOfOrbits; i++)
    {
        float angle = (projectile.orbitCircle * Mathf.PI / projectile.numberOfOrbits) * i;

        float x = Mathf.Sin(angle) * projectile.orbitRadius;
        float z = Mathf.Cos(angle) * projectile.orbitRadius;
        Vector3 pos = new Vector3(0, 0, 0);

        if ((directionAngle >= 0 && directionAngle < 90) || (directionAngle >= 271 && directionAngle < 360))
            pos = new Vector3(0, x, z);
        else if (directionAngle < 91)
            pos = new Vector3(x, 0, z);
        else if (directionAngle < 270)
            pos = new Vector3(0, -x, z);
        else
            pos = new Vector3(-x, 0, z);

        pos = centerDirection * pos;

        Instantiate(projectileOrbitPrefab, transform.position + pos, transform.rotation);

    }
}

And the orbitSource Script:

public void OrbitSource()
{
    transform.position = centerTransform.position + pos;
}