instantiating elements in UI/Canvas

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Hey guys. Basically all i need to do is randomly spawn sprites that fall across the screen on the screen space overlay canvas. Instantiate needs a vector 3 as a position, but the canvas does not have a vector3 position just a rect transform. So either need to instantiate using rect transform (which doesnt seem like it woul dbe possible) or get the equivelent postion in the UI using a vector. Hope that makes sense.

Something like this

 GameObject randomGerm = germs[Random.Range(0, germs.Length)];
 
 Vector3 spawnPosition = new Vector3(Random.Range(-spawnValues.x, spawnValues.x) ,spawnValues.y,spawnValues.z);
 
                 Quaternion spawnRotation = Quaternion.identity; //new Quaternion ();
 
                 GameObject germSpawned = Instantiate (randomGerm, spawnPosition, spawnRotation) as GameObject;

But this will only spawn in world space not the UI/Canvas.. hope you know what im aiming at

thanks guys

Answer 1

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Answer by pfreese · Mar 18, 2015 at 05:28 AM

The important thing is to parent the newly instantiated object to the canvas.

You can also instantiate the object using the single parameter version of Object.Instantiate():

 public static Object Instantiate(Object original);

and then modify the transform of the returned object:

 GameObject germSpawned = Instantiate(randomGerm) as GameObject;
 germSpawned.transform.SetParent(canvas.transform);
 germSpawned.transform.localPosition = spawnPosition;
 germSpawned.transform.localRotation = spawnRotation;

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p_unity · Mar 18, 2015 at 09:25 AM 1

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Hey there.. Well germs is an array of gameObjects (the images have empty gameobjects as parents for animation purposes). Where do i set the parent? before setting the rectTransform components? Also that is still using Vector 3s, as spawnPostiin is a Vector3 and i cant use a vector3 to place a UI image in screen space.

pfreese · Mar 18, 2015 at 11:06 PM 0

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Does the GameObject you are cloning have a plain old Transform or a RectTransform? Either can be used to set the position in the Canvas, but the interface will be slightly different for each. However, you will set the parent the same way:

germSpawned.transform.SetParent(canvasObject.transform);

Using the Transform component, you can set the X,Y values of the position; they should be relative to the center of the canvas. If the game object has a RectTransform (or you replace the transform with a RectTransform using AddComponent), then you can set the anchoredPosition and it will use the behavior as determined by the anchorMin/anchorMax/pivot values.

zedsmith52 · Jun 01, 2018 at 09:32 AM 0

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You could rewrite those 4 lines as:

 GameObject germSpawned = Instantiate(randomGerm, spawnPosition, spawnRotation) as GameObject;
  germSpawned.transform.SetParent(canvas.transform);

but either way works just as well ;)

instantiating elements in UI/Canvas

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