Drawing Rectangles in 2D for hitboxes: fighting game

Questions & Answers
1

This is about to drive me insane. My goal is to draw a 2D rectangle with the same dimensions as the hitbox I want to create in Unity. Because my Box Collider 2D isn’t visible, I’m trying to make a visual aid to see where it actually is in the world.

Unfortunately, drawing this rectangle has been a far bigger headache than I would have hoped. I’ve searched for many examples as to how to do this - I’ve looked at GL.DrawTexture and GL.Box, but this will not work because drawing this rectangle is an Animation Event. In short, I am calling a function during a particular frame that is dynamically creating a hitbox, and then I am trying to get rid of it a few frames later. The rectangle I am drawing is only relevant for these frames, and I’m not doing anything in OnGUI.

Right now, I have:

	Texture2D tex = new Texture2D (1, 1);
	tex.SetPixel (0, 0, Color.black);
	tex.Apply ();
	Rect pos = new Rect (transform.position.x, transform.position.y, 10, 10);
	Sprite newSprite = Sprite.Create (tex, pos, new Vector2 (0.5f, 0.5f), 128);
	GameObject obj = new GameObject ();
	obj.name = "Hitbox";
	obj.AddComponent<SpriteRenderer> ();
	SpriteRenderer spr = obj.GetComponent<SpriteRenderer> ();
	spr.sprite = newSprite;

I am trying to draw a little black box in front of the player during a walk animation. Not only does this not work, I can’t get rid of the rectangle when I need to. The rectangle doesn’t even appear where it should - it’s always at 0,0.

Any help would be appreciated; this problem is making me lose my mind.

2

You can use Debug.DrawLine to draw 4 lines at any point from any method. Downside, is that they are only visible in editor.

So based off your existing code, you could do something like this:

//Top Line
Debug.DrawLine(new Vector3(transform.position.x - 0.5f, transform.position.y + 0.5f, 0),
new Vector3(transform.position.x + 0.5f, transform.position.y + 0.5f, 0), Color.black);
//Right Line
Debug.DrawLine(new Vector3(transform.position.x + 0.5f, transform.position.y + 0.5f, 0),
new Vector3(transform.position.x + 0.5f, transform.position.y - 0.5f, 0), Color.black);
//Bottom Line
Debug.DrawLine(new Vector3(transform.position.x + 0.5f, transform.position.y - 0.5f, 0),
new Vector3(transform.position.x - 0.5f, transform.position.y - 0.5f, 0), Color.black);
//Left Line
Debug.DrawLine(new Vector3(transform.position.x - 0.5f, transform.position.y - 0.5f, 0),
new Vector3(transform.position.x - 0.5f, transform.position.y + 0.5f, 0), Color.black);

Another option is you could use a OnDrawGizmos() and do something like (drawBlackBox would be a class variable or something similar):

void OnDrawDizmos()
{
    if (drawBlackBox)
    {
        Gizmos.color = Color.black;
        Gizmos.DrawWireCube(transform.position.x, new Vector3(1f, 1f, 1f));
    }
}

The downside of Gizmos is they’re only visible in the editor as well.

If you want it to work anywhere, and it doesn’t need to be too complex, then you could consider using a Quad Primitive and appropriate texture/material and make it a prefab. Instantiate it when the game starts or character spawns or whatever, store a reference to it and then just turn it on/off/update when necessary.