I need help with a Block Spawner

Question

I am trying to make a block which can spawn different blocks..I am not very good at coding unfortunately..can anyone help? this is what i managed till now (its in java script):

 #pragma strict
 
 function Start () {
 
 }
 
 static function Instantiate( original : Object, position : Vector3, rotation : Quaternion ) : Object {
     transform.position = Random.insideUnitSphere * 10;
 }
 
 function Update () {
 
 }

Answer 1

You need to break it down ....

1

Let's first look at Instantiate : http://docs.unity3d.com/Documentation/ScriptReference/Object.Instantiate.html

From the Unity Script Reference above we get an example script, and can make a simple script :

 var prefabBlock : Transform;
 
 function Start()
 {
     // Instantiates 10 copies of prefabBlock each 2 units apart from each other
     for ( var i : int = 0; i < 10; i ++ ) 
     {
         Instantiate( prefabBlock, Vector3(i * 2.0, 0, 0), Quaternion.identity );
     }
 }

2

Great, so at start 10 blocks are spawned, 2 units apart from each other though! Let's make them spawn at a specific place. You want to use a 'Spawn Block', so add that to the script, then use its position in the Instantiate. Make sure you have a 'SpawnBlock' on the stage, then drag it into the script's inspector :

 var spawnBlock : Transform;
 
 var prefabBlock : Transform;
 
 function Start()
 {
     // Instantiates 10 copies of prefabBlock each 2 units apart from each other
     for ( var i : int = 0; i < 10; i ++ ) 
     {
         Instantiate( prefabBlock, spawnBlock.position, Quaternion.identity );
     }
 }

Now all 10 cubes should spawn at the same position as the spawnBlock object.

3

Next to look at making it more complex, let's change it so that it spawns a block every time the SpaceBar is pressed. We can put the instantiate in a function, and then just call that function when we want a block. Then we need to check every update for if the SpaceBar has been pressed :

 var spawnBlock : Transform;
 var prefabBlock : Transform;
 
 var spawnTime : float = 3.0;
 
 function Update()
 {
     if ( Input.GetKeyDown(Keycode.Space) )
     {
         SpawnTheBlock();
     }
 }
 
 function SpawnTheBlock()
 {
     Instantiate( prefabBlock, spawnBlock.position, Quaternion.identity );
 }

4

Now we can spawn enemies, but how to make it so the enemys are spawned by themselves, and at random intervals? For this, there is a handy command called InvokeRepeating : http://docs.unity3d.com/Documentation/ScriptReference/MonoBehaviour.InvokeRepeating.html

 var spawnBlock : Transform;
 var prefabBlock : Transform;
 
 var spawnTime : float = 3.0;
 
 function Start()
 {
     InvokeRepeating( "SpawnTheBlock", 0.1, spawnTime );
 }
 
 function SpawnTheBlock()
 {
     Instantiate( prefabBlock, spawnBlock.position, Quaternion.identity );
 }

5

Hey, it's nearly working, but how many Blocks have been spawned? Let's add a counter :

 var spawnBlock : Transform;
 var prefabBlock : Transform;
 var spawnTime : float = 3.0;
 
 var spawnCount : int = 3.0;
 
 function Start()
 {
     InvokeRepeating( "SpawnTheBlock", 0.1, spawnTime );
 }
 
 function SpawnTheBlock()
 {
     Instantiate( prefabBlock, spawnBlock.position, Quaternion.identity );
     spawnCount += 1; // Note : this can be written as spawnCount ++;
 }
 
 function OnGUI()
 {
     GUI.Box( Rect( (Screen.width * 0.5) - 50, 10, 100, 25 ), "Blocks : " + spawnCount.ToString() );
 }

6

Nice, ..... hey wait! there are too many Blocks! Lets cap the amount of blocks that can be spawned. We need to stop the InvokeRepeating : http://docs.unity3d.com/Documentation/ScriptReference/MonoBehaviour.CancelInvoke.html

 var spawnBlock : Transform;
 var prefabBlock : Transform;
 var spawnTime : float = 3.0;
 var spawnCount : int = 3.0;
 
 var maximumSpawnCount : int = 10;
 
 function Start()
 {
     InvokeRepeating( "SpawnTheBlock", 0.1, spawnTime );
 }
 
 function SpawnTheBlock()
 {
     Instantiate( prefabBlock, spawnBlock.position, Quaternion.identity );
     spawnCount += 1; // Note : this can be written as spawnCount ++;
     
     if ( spawnCount >= maximumSpawnCount )
     {
         CancelInvoke( "SpawnTheBlock" );
     }
 }
 
 function OnGUI()
 {
     GUI.Box( Rect( (Screen.width * 0.5) - 50, 10, 100, 25 ), "Blocks : " + spawnCount.ToString() );
 }

7

Phew, now only 10 blocks spawn. Wow, this is all pretty good. But I forgot something, you want to spawn a different random block each time. For this we need places to put the blocks, and a Random number to choose a block, then if that : http://docs.unity3d.com/Documentation/ScriptReference/Random.Range.html

 var spawnBlock : Transform;
 
 var prefabBlock1 : Transform;
 var prefabBlock2 : Transform;
 var prefabBlock3 : Transform;
 
 var spawnTime : float = 3.0;
 var spawnCount : int = 3.0;
 var maximumSpawnCount : int = 10;
 
 function Start()
 {
     InvokeRepeating( "SpawnTheBlock", 0.1, spawnTime );
 }
 
 function SpawnTheBlock()
 {
     var rnd : int = Random.Range( 1, 4 ); // 1 to 3 is written 1,4 as the 4 is never returned, see the docs
     
     if ( rnd == 1 )
     {
         Instantiate( prefabBlock1, spawnBlock.position, Quaternion.identity );
     }
     else if ( rnd == 2 )
     {
         Instantiate( prefabBlock2, spawnBlock.position, Quaternion.identity );
     }
     else if ( rnd == 3 )
     {
         Instantiate( prefabBlock3, spawnBlock.position, Quaternion.identity );
     }
     
     spawnCount ++;
     
     if ( spawnCount >= maximumSpawnCount )
     {
         CancelInvoke( "SpawnTheBlock" );
     }
 }
 
 function OnGUI()
 {
     GUI.Box( Rect( (Screen.width * 0.5) - 50, 10, 100, 25 ), "Blocks : " + spawnCount.ToString() );
 }

And there we have it, one multi-random-block spawning script, to spawn at BigBlocks position =]

Answer 2

To spawn different blocks (prefabs) you are going to need a way to provide your spawn method a list or some form of set to choose from.

Example in C#:

 //Somewhere in your setup you would need to define the prefabs for each block type...in this case all would be subclassed from CustomBlockThing.
 Public List<CustomBlockThing> BlockTypesList = new List<CustomBlockThing>();
 
 //...assume we have populated the list. Since the list is set to Public, you could do so by dragging objects into it in the editor.
 
 //Here is our method to spawn new blocks. It selects 1 randomly from the types of blocks available in the previously declared BlocksList
 GameObject SpawnBlocks(int blockType = -1){
 
     //This allows us to specify the type if we do not want random...
     if (blockType == -1){
 
         CustomBlockThing randomBlock;
 
         //Generate a random number in the range of 1 to the number of block types we have defined.
         int randomBlockType = Random.Range(1, BlockTypes.length);
         
         
         //Here we use that random number to select a block type to spawn
         randomBlock = Instantiate(BlockTypes[randomBlockType], transform.position, transform.rotation) as CustomBlockThing;
 
         //Pass a reference to the newly created random typed CustomBlockThing to the caller
         return randomBlock;
     }
     else{
         
         //should probably generate an error of some type if the blockType is out of range, but I will instead assume we ALWAYS return a block of some type...
         if (blockType > BlockTypes.length || blockType < 1){
             CustomBlockThing randomBlock;
 
             //Generate a random number in the range of 1 to the number of block types we have defined.
             int randomBlockType = Random.Range(1, BlockTypes.length);
 
             //Here we use that random number to select a block type to spawn
             randomBlock = Instantiate(BlockTypes[randomBlockType], transform.position, transform.rotation) as CustomBlockThing;
             
             //Pass a reference to the newly created random typed CustomBlockThing to the caller
             return randomBlock;
         }
         
         CustomBlockThing specificBlock;
         
         //note that we still use the list, but ask for a specific item/index based on the blockType variable.
         randomBlock = Instantiate(BlockTypes[randomBlockType] transform.position, transform.rotation) as CustomBlockThing;
 
         //Pass a reference to the newly created, specific type of, CustomBlockThing to the caller
         return specificBlock;
     }
 }

If you are simply randomizing the values for each block as it is spawned, you may not need to do the above, but instead something like (psueudo-code)

 newBlock = instantiate a new block object at position and heading
 
 newBlock.height = some random value in a limited range
 newBlock.position = some random offset
 newBlock.velocity = ...
 newBlock.otherProperty = some other random value
 
 done.

Answer 3

Answer by nicktheuma · Sep 18, 2012 at 06:53 PM

thanks!, actually i managed abit further..the biggest problem I have now is rendering all the objects I have..it takes forever..and im planning to add many more..

 #pragma strict
 
 function Start () {
 
 }
 
 
 // Instantiates 100 copies of prefab each 2 units apart from each other
 
 var prefab : Transform;
 var prefab1 : Transform;
 var prefab2 : Transform;
 
 for (var i : int = 0;i < 100000000; i++) {
     Instantiate (prefab, (Random.insideUnitSphere * 5), Quaternion.identity);
 }
 
 for (var j : int = 0;j < 100000000; j++) {
     Instantiate (prefab1, (Random.insideUnitSphere * 5), Quaternion.identity);
 }
 
 for (var k : int = 0;k < 100000000; k++) {
     Instantiate (prefab2, (Random.insideUnitSphere * 5), Quaternion.identity);
 }
 
 
 
 
 function Update () {
 
 }

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