Shader "TextureChange" {
Properties {
	_Blend ("Blend", Range (0, 1) ) = 0.5 
	_Color ("Main Color", Color) = (1,1,1,1)
	_MainTex ("Texture 1", 2D) = "white" {}
	_Texture2 ("Texture 2", 2D) = ""
	_BumpMap ("Normalmap", 2D) = "bump" {}
}

SubShader {
	Tags { "RenderType"="Opaque" }
	LOD 300
	Pass {
		SetTexture[_MainTex]
		SetTexture[_Texture2] { 
			ConstantColor (0,0,0, [_Blend]) 
			Combine texture Lerp(constant) previous
		}		
	}

	CGPROGRAM
	#pragma surface surf Lambert
	
	sampler2D _MainTex;
	sampler2D _BumpMap;
	fixed4 _Color;
	sampler2D _Texture2;
	float _Blend;
	
	struct Input {
		float2 uv_MainTex;
		float2 uv_BumpMap;
		float2 uv_Texture2;
		
	};
	
	void surf (Input IN, inout SurfaceOutput o) {
		fixed4 t1 = tex2D(_MainTex, IN.uv_MainTex) * _Color;
		fixed4 t2 = tex2D (_Texture2, IN.uv_MainTex) * _Color;
		
		o.Albedo = lerp(t1, t2, _Blend);
		o.Normal = UnpackNormal(tex2D(_BumpMap, IN.uv_BumpMap));
	}
	ENDCG  
	}
	
	FallBack "Diffuse"
}

using UnityEngine;
using System.Collections;

public class Sh1 : MonoBehaviour {

	Texture tx1;
	Texture tx2;
	Texture newTx;
	bool triggerChange = false;
	float blendRange = 1.0f;
	
	void Start () {
		
		
		//texture load
		tx1 = Resources.Load("img") as Texture;
		print(tx1);
		
		tx2 = Resources.Load("backHD") as Texture;
		print(tx2);
		
		
		gameObject.renderer.material.SetFloat("_Blend" , blendRange);//initialize shader
	}
	
	public void changeTexture(int arg)
	{
		
		if(arg == 0)
			newTx = tx1;
		else if(arg ==1)
			newTx = tx2;
		
		gameObject.renderer.material.mainTexture = newTx;
		triggerChange = true;
	}

	
	private int testC = 0;
	void Update () {
		
		
		if(triggerChange == true)
		{
			blendRange = blendRange - 0.01f; //change speed
			
			gameObject.renderer.material.SetFloat("_Blend" , blendRange);
			
			if(blendRange <= 0)
			{
				triggerChange = false;
				blendRange = 1.0f;
				gameObject.renderer.material.SetTexture("_Texture2" , newTx);
				gameObject.renderer.material.SetFloat("_Blend" , 1);
				
				print("changeComplete");
			}
		}
		
		
		if(Input.GetKeyDown(KeyCode.A))
		{
			print("change!");
			changeTexture(testC % 2);
			
			++testC;
		}
		gameObject.transform.Rotate(Vector3.up , 1f);
	}
}