u3d_Shader_effects笔记6 第二章 animating sprite

1.前面的心情

上班看shader我也是醉了。写完这篇看代码去了，不过看着看着恐怕就会困....

还有就是上天，我该怎么做，下一步，大懒；

2.参考源头

http://blog.csdn.net/candycat1992/article/details/18662601

http://www.cppblog.com/lai3d/archive/2008/10/23/64889.html

群里问大神

3.实现效果和代码

实现效果：猴子的animation动画；16张小图顺序变化；但由于此图并未对齐，结果不理想，没有人行走的那张效果好

代码：两部分，1.cs部分，实现时间time，获取每张小图的x、y的index下标，并传入shader值， 2.shader中根据index下标，偏移值，来计算一种映射关系，使（0,0）-(1,1,)映射到每个小块上；

(1).cs部分：

public class AnimationTest : MonoBehaviour {

	public float speed = 5.0f;
    public int _CellAmountX = 8; 

	float timeValue = 0.0f;
    float timeOffsetY = 0.0f;

    private bool bIsUp_Bottom = true;
	void Start ()
	{
        transform.renderer.material.SetFloat("_CellAmountX", _CellAmountX);
	}

	// Update is called once per frame
	void FixedUpdate () 
	{
        timeValue = Mathf.Ceil(Time.time * speed % _CellAmountX);

        Debug.Log("timeValue:" + timeValue);//上log图，显示x的index

	    if (timeValue==_CellAmountX)  
	    {
            if (bIsUp_Bottom)
	        {
                timeOffsetY = Mathf.Abs(timeOffsetY - 1.0f);//当达到x最右侧，进行上下Y的index切换
	        }
	        bIsUp_Bottom = false;
	    }
	    else
	    {
	        bIsUp_Bottom = true;
	    }

		transform.renderer.material.SetFloat("_TimeValue", timeValue);
        transform.renderer.material.SetFloat("_TimeOffsetY", timeOffsetY);
	}
}

　　(2).shader部分，进行纹理坐标的映射关系；

Shader "Custom/AnimateSprites" {
	Properties {
		_MainTex ("Base (RGB)", 2D) = "white" {}
		
		// Create the properties below
		_CellAmountX ("Cell Amount", float) = 8
		_TimeValue ("Time Value", float) = 0.0
		_TimeOffsetY("_TimeOffsetY",float ) = 0.0 
	}
	SubShader {
		Tags { "RenderType"="Opaque" }
		LOD 200
		
		CGPROGRAM
		#pragma surface surf Lambert

		sampler2D _MainTex;
		
		//Create the connection to the properties inside of the 
		//CG program
		float _CellAmountX;
		float _TimeValue;
		float _TimeOffsetY;

		struct Input {
			float2 uv_MainTex;
		};

		void surf (Input IN, inout SurfaceOutput o) {
			//Lets store our UVs in a seperate variable
			float2 spriteUV = IN.uv_MainTex;
			
			//Lets calculate the width of a singe cell in our
			//sprite sheet and get a uv percentage that each cel takes up.
			float cellUVPercentage = 1.0/_CellAmountX;
			
			//Animate the uv's forward by the width precentage of 
			//each cell
			float xValue = spriteUV.x;
			xValue += _TimeValue;
			xValue *= cellUVPercentage;
			
			float cellUVPercentage_Y = 1.0/2.0f;
			float yValue = spriteUV.y;
			yValue += _TimeOffsetY;
			yValue*=cellUVPercentage_Y;

			spriteUV = float2(xValue, yValue);
			
			half4 c = tex2D (_MainTex, spriteUV);
			o.Albedo = c.rgb;
			o.Alpha = c.a;
		}
		ENDCG
	} 
	FallBack "Diffuse"
}