instantiate objects between two mouseclicks

I am a newby to c# and unity!! I would appreciate a little help with my problem which is that I want to instantiate objects as I drag my mouse across the screen.

This is my script so far;

	if (Input.GetMouseButton (0)) 



		ghoststartspot = Input.mousePosition;

		Debug.Log (ghoststartspot);


			Vector3 difference = blockmousescript.currentmousepoint - ghoststartspot;

			for (int change = 0; change < difference.magnitude; change++)

				Vector3 spawnblock = ghoststartspot + difference.normalized * change;

				Vector3 blockspawn = new Vector3 (Mathf.RoundToInt (spawnblock.x), Mathf.RoundToInt (blockmousescript.currentmousepoint.y + height), Mathf.RoundToInt (spawnblock.z));

			GameObject blockspawnerx = Instantiate (ghostplenty, blockspawn, Quaternion.identity); 

		As you can see I use a for loop and try to use a normalized vector to represent the direction I want to instantiate in. Then the i++ in the for loop would allow me to instantiate "i" further along the vector each time the loop iterates through.

However while this mostly works it spawns hundreds of different objects at each point along the loop.

I have no idea why this is happening and would appreciate help to improve my understanding here. Ty

Instead of GetMouseButton, you should be using GetMouseButtonDown. On the first click, save the mouse position to a variable. On the second click, subtract that position from the new current position and add half of it to the old position. That will give you the position in between last and current mouse position. Also instantiate your object and place it on second click. If it’s the first or second click you could just use a boolean and toggle it true and false on each click.