3rd person 3D aiming

Questions & Answers
1

Hello.

Currently I’m trying to make an aiming system for a 3D, 3rd person game. My goal is to have the character aim the attack (a projectile, in this case) in a direction corresponding to the mouse position relative to the character’s own position.
Example: if the mouse pointer is above and to the left of the character, I want the attack to be aimed forward, but with an upward and a leftward angle; this angle should increase the further the mouse pointer is relative to the character.

Unfortunately, I can’t quite get this system to work. What am I doing wrong?

public override void Aim(float range, Camera mainCamera, Transform firingPoint, LayerMask terrainMask)
    {
        Ray ray = mainCamera.ViewportPointToRay(Input.mousePosition);
        float targetRayDistance = Vector3.Distance(mainCamera.transform.position, firingPoint.position) / Mathf.Cos(Vector3.Angle(mainCamera.transform.forward, -firingPoint.forward)) + range; //this takes into the account the angle the camera is at relative to the character, and compensates



        if (Physics.Raycast(ray, targetRayDistance, terrainMask, QueryTriggerInteraction.Ignore)) 
        {
            firingPoint.rotation = Quaternion.LookRotation(ray.GetPoint(targetRayDistance), firingPoint.up); //if the Raycast collides with terrain, that means the projectile will too; I don't want that; therefore the projectile will be aimed horizontally instead
        }
        else
        {
            firingPoint.rotation = Quaternion.LookRotation(ray.GetPoint(targetRayDistance));
        }        
    }
2

Alright, figured it out after a bit more searching. The answer is here c# - Mouse based aiming Unity3d - Stack Overflow but I adapted it slightly to fit what I was trying to do.

Vector3 GetMousePositionInPlaneOfLauncher () {
    Plane p = new Plane(mainCamera.transform.forward, firingPoint.position);
    Ray r = mainCamera.ScreenPointToRay(Input.mousePosition);
    float d;
    if(p.Raycast(r, out d)) {
        Vector3 v = r.GetPoint(d);
        return v;
    }

    throw new UnityException("Mouse position ray not intersecting launcher plane");
}

firingPoint.LookAt(GetMousePositionInPlaneOfLauncher());