Rotating and positioning a row of gameobjects without gaps

Question

I have a prefab of a house with a bit of road attached, like so:

I want to arrange these side-by-side to create a street, but I also want to have them at a slight angle so that the road seems to head off into the distance. Something more like this:

I've been able to place them and rotate them, but I'm having a lot of trouble figuring out the positioning. I'm guessing there's some maths trick I'm not applying or something.

This is my code so far:

        int houseCount = 0;
        float offsetX = 0;
        float offsetZ = 0;
        while (houseCount < 30)
        {
            GameObject house = GameObject.Instantiate(housePrefab);
            house.transform.Rotate(new Vector3(0,-20f,0), Space.Self);
            house.transform.position = new Vector3(offsetX, 0, offsetZ);

            // Calculate offset for next house
            HouseUnit unit = house.GetComponent<HouseUnit>();
            MeshRenderer renderer = unit.GetHouseBase().GetComponent<MeshRenderer>();
            Vector3 size = renderer.bounds.size;
            offsetX += size.x;
            offsetZ += size.z / 2f;

            Debug.Log(size);
            houseCount++;
        }

unit.GetHouseBase() returns the road segment, which is a simple plane. I figured that was the most logical bit to base the positioning on since it's a) the widest part, and b) the bit I need to connect up.

Running this gives the following result:

They're not lining up too badly, but I can't figure out how to close that gap. Has anyone got any suggestions, or resources they can point me at? Thanks in advance.

Answer 1

See MeshRenderer has wrong bounds when rotated

As a short summary:

• Unity takes Mesh.bounds which are in local space (unscaled, unrotated, untranslated)
• Unity then wraps this bounds within the Renderer.bounds
• Since Bounce are always world axis aligned the Renderer.bounds grows when rotating the object in order to fit the now rotated mesh bounds within

Just re-posting the image for better illustration

---

So what I would do is

1. Have a common parent object
2. Do all house placements while parent object is not rotated
   => Can rely on Renderer.bounds to be accurate
3. Then in the end rotate the parent according to your needs
   => and all children (houses) automatically along with it
4. [optional] If you then really really do not want that parent object there for whatever reason, simply once you are done un-parent all the houses maintaining their current positions and rotations and destroy the parent

something like e.g.

// either already have that common parent or create one now
var parent = new GameObject().transform;

// if using previously existing parent store original position and rotation
var position = parent.position;
var rotation = parent.rotation;

// ensure not rotated
parent.position = Vector3.zero;
parent.rotation = Quaternion.identity;

// span houses into parent
var offsetX = 0f;
for(var houseCount = 0; houseCount < 30; houseCount++)
{
    var house = Instantiate(housePrefab, parent, Vector3.right * offsetX, Quaternion.identity);

    // Calculate offset for next house
    var size = house.GetComponentInChildren<Renderer>().bounds.size;
    offsetX += size.x;
}

parent.position = position;
// either reapply previous rotation (if already was rotated)
parent.rotation = rotation;
// or rotate now to your desired 20°
parent.rotation = Quaternion.Euler(0, -20f, 0);


// [optional] as said if you then d not want the parent anymore you could also add
while(parent.childCount > 0)
{
    var child = parent.GetChild(0);
    child.SetParent(parent.parent, true);
}
Destroy(parent.gameObject);