Instantiating objects at runtime in Unity - Step-by-Step Execution

Concept Flow - Instantiating objects at runtime

Start

↓

Load Prefab

↓

Call Instantiate()

↓

New Object Created

↓

Set Position/Rotation

↓

Object Active in Scene

↓

End

The program loads a prefab, calls Instantiate to create a new object, sets its position and rotation, then the object appears active in the scene.

Execution Sample

Unity

public GameObject prefab;

void Start() {
  GameObject obj = Instantiate(prefab, new Vector3(0,0,0), Quaternion.identity);
}

This code creates a new instance of the prefab at position (0,0,0) with no rotation when the game starts.

Execution Table

Step	Action	Prefab State	New Object State	Output
1	Start method called	Prefab loaded	No new object	No output
2	Instantiate called	Prefab loaded	New object created (active immediately)	No output
3	Set position to (0,0,0)	Prefab loaded	New object position set	No output
4	Set rotation to identity	Prefab loaded	New object rotation set	No output
5	New object active in scene	Prefab loaded	New object active and visible	No output

💡 Instantiation complete, new object is active in the scene.

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
prefab	Loaded prefab object	Loaded prefab object	Loaded prefab object	Loaded prefab object	Loaded prefab object
obj	null	New GameObject instance	Position set to (0,0,0)	Rotation set to identity	Active in scene

Key Moments - 2 Insights

Why does the new object appear only after setting position and rotation?

Because Instantiate creates the object and it is active immediately, but the object appears correctly placed only after position and rotation are assigned, as shown in steps 2-5 in the execution_table.

Is the prefab itself changed when we instantiate a new object?

No, the prefab remains unchanged as seen in the prefab state column in the execution_table; only a new copy is created.

Visual Quiz - 3 Questions

Look at the execution_table, what is the state of 'obj' after step 3?

A New object active and visible

B No new object created yet

C New GameObject instance with position set to (0,0,0)

D Prefab is modified

💡 Hint

Check the 'New Object State' column at step 3 in the execution_table.

At which step does the new object become active in the scene?

A Step 2

B Step 3

C Step 5

D Step 1

💡 Hint

Look for 'active' in the 'New Object State' column in the execution_table.

If we skip setting rotation, what changes in the execution_table?

A Prefab would be modified

B Step 4 row would be missing or show no rotation set

C New object would not be created

D Object would be active earlier

💡 Hint

Refer to the 'Action' column in the execution_table for step 4.

Concept Snapshot

Instantiate(prefab, position, rotation) creates a new object copy at runtime.
Prefab stays unchanged.
Set position and rotation to place the object.
New object becomes active and visible after setup.
Use in Start() or any method to spawn objects dynamically.

Full Transcript

This visual trace shows how Unity creates a new object from a prefab during runtime. First, the prefab is loaded. Then, Instantiate is called to make a new copy. The new object is active immediately. Next, its position and rotation are set to place it correctly in the scene. Finally, the object appears correctly placed and visible. The prefab itself does not change. Variables track the prefab and new object states step-by-step. Key moments clarify why the object appears only after setup and that the prefab remains unchanged. Quiz questions test understanding of object state at each step and effects of skipping steps.