u3d_Shader_effects笔记5 第二章 通过UV，进行纹理移动

1.前面心情

公司最近打包，像我等小弟闲着，看代码容易困，没事偷着学shader，不过还是要多交流才行。

2.本文参考

这次参考比较多；由texture uv延伸问题多，主要是不明白变量定义；

http://blog.csdn.net/candycat1992/article/details/17754427  纹理移动，以及一个新shader，更改水纹理的效果

http://www.jianshu.com/p/7b9498e58659  介绍shaderLab比较详细了

u3d manual 必备

3.代码

本文做的事情，其实就是解释代码了。。主要是读http://blog.csdn.net/candycat1992/article/details/17754427的代码；顺便查UnityManual

首先是书中例子代码：

Shader "Custom/ScrollingUVs" {
	Properties {
		_MainTex ("Base (RGB)", 2D) = "white" {}
		// Add two properties
		_ScrollXSpeed ("X Scroll Speed", Range(0, 10)) = 2
		_ScrollYSpeed ("Y Scroll Speed", Range(0, 10)) = 2
	}
	SubShader {
		Tags { "RenderType"="Opaque" }
		LOD 200
		
		CGPROGRAM
		#pragma surface surf Lambert

		sampler2D _MainTex;
		fixed _ScrollXSpeed;
		fixed _ScrollYSpeed;

		struct Input {
			float2 uv_MainTex;
		};

		void surf (Input IN, inout SurfaceOutput o) {
			fixed2 scrolledUV = IN.uv_MainTex;
			
			fixed xScrollValue = _ScrollXSpeed * _Time.y;
			fixed yScrollValue = _ScrollYSpeed * _Time.y;
			
			scrolledUV += fixed2(xScrollValue, yScrollValue);
			
			half4 c = tex2D (_MainTex, scrolledUV);
			o.Albedo = c.rgb;
			o.Alpha = c.a;
		}
		ENDCG
	} 
	FallBack "Diffuse"
}

　　

其次是http://blog.csdn.net/candycat1992/article/details/17754427后面处理水的代码：

Shader "Mobile/Transparent/Vertex Color" {
	Properties {
		_Color ("Main Color", Color) = (1,1,1,1)
		_SpecColor ("Spec Color", Color) = (1,1,1,0)
		_Emission ("Emmisive Color", Color) = (0,0,0,0)
		_Shininess ("Shininess", Range (0.1, 1)) = 0.7
		_MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}
	}
	
	Category {
		Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}
		ZWrite Off
		Alphatest Greater 0
		Blend SrcAlpha OneMinusSrcAlpha 
		SubShader {
			Material {
				Diffuse [_Color]
				Ambient [_Color]
				Shininess [_Shininess]
				Specular [_SpecColor]
				Emission [_Emission]	
			}
			Pass {
				ColorMaterial AmbientAndDiffuse
				Fog { Mode Off }
				Lighting Off
				SeparateSpecular On
	        	SetTexture [_MainTex] {
	            Combine texture * primary, texture * primary
	        }
	        SetTexture [_MainTex] {
	            constantColor [_Color]
	            Combine previous * constant DOUBLE, previous * constant
	        }  
			}
		} 
	}
}

　　

4.我学到什么：

(1).内置变量的查看  

http://docs.unity3d.com/Manual/SL-UnityShaderVariables.html

C:Program Files (x86)UnityEditorDataUnityShaderVariables.cginc 

CBUFFER_START(UnityPerCamera)
	// Time values from Unity
	uniform float4 _Time;
	uniform float4 _SinTime;
	uniform float4 _CosTime;
	uniform float4 unity_DeltaTime; // dt, 1/dt, smoothdt, 1/smoothdt

　　

fixed xScrollValue = _ScrollXSpeed * _Time.y; 

Name	Type	Value
_Time	float4	Time since level load (t/20, t, t*2, t*3), use to animate things inside the shaders.
_SinTime	float4	Sine of time: (t/8, t/4, t/2, t).
_CosTime	float4	Cosine of time: (t/8, t/4, t/2, t).
unity_DeltaTime	float4	Delta time: (dt, 1/dt, smoothDt, 1/smoothDt).

_Time.y 也就是float4中第二个值，t,即游戏开始到现在的时间； 如果用t/20的话，_ScrollXSpeed * _Time.y;每帧的差值会小一些；

不过smoothDt是什么？应该是dt每帧差值，更平滑的处理？

（2）.材质属性的设置，Shininess：

 _Shininess ("Shininess", Range (0.1, 1)) = 0.7  

　　上上一章说明了光源的三种属性：ambientdiffusespecular；

材质也有对应属性：

		Material
		{
			Diffuse [_Color]
			Ambient [_Color]
			Shininess [_Shininess]
			Specular [_SpecColor]
			Emission [_Emission] 
		}

　　Shininess  　　　　　　　　http://docs.unity3d.com/Manual/SL-Material.html

Shininess number: The sharpness of the highlight, between 0 and 1. At 0 you get a huge highlight that looks a lot like diffuse lighting, at 1 you get a tiny speck.

 　　　　　　　　　　　　　　http://my.oschina.net/u/1469992/blog/273307

即和Specular相关的镜面指数，指定了镜面反射加亮的大小和集中性，0表示不聚焦，整个表面均匀加亮；1表示聚焦，光斑小，最亮。

（3）. Alphatest Greater 0 

http://docs.unity3d.com/Manual/SL-AlphaTest.html

Greater 0 即大于0的都通过，对于本此实验，没用

http://blog.sina.com.cn/s/blog_471132920101d8z1.html 讲了alphaTest实际使用，不过最后一个应该错了；

使用alphaTest，可以使场景更加柔和，同时有实体感；

（4）. Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}

内容有些多；http://docs.unity3d.com/Manual/SL-SubShaderTags.html
"Queue"="Transparent"

There are four pre-defined render queues, but there can be more queues in between the predefined ones. The predefined queues are:
一共四个预定义队列临界值，不过可以在此之间设置新预定义值
Background - this render queue is rendered before any others. You’d typically use this for things that really need to be in the background.
Geometry (default) - this is used for most objects. Opaque geometry uses this queue.
非透明几何数据使用此

AlphaTest - alpha tested geometry uses this queue. It’s a separate queue from Geometry one since it’s more efficient to render alpha-tested objects after all solid ones are drawn.
从geometry中分出来的，在所有solid绘制后，AlphaTest，更有效的操作
Transparent - this render queue is rendered after Geometry and AlphaTest, in back-to-front order. Anything alpha-blended (i.e. shaders that don’t write to depth buffer) should go here (glass, particle effects).
透明，alpha混合操作；不进行z-write写入深度buffer;glass,particle效果
Overlay - this render queue is meant for overlay effects. Anything rendered last should go here (e.g. lens flares).
最上层效果，如镜头光晕

For special uses in-between queues can be used. Internally each queue is represented by integer index; Background is 1000, Geometry is 2000, AlphaTest is 2450,Transparent is 3000 and Overlay is 4000. If a shader uses a queue like this:
Tags { "Queue" = "Geometry+1" }
This will make the object be rendered after all opaque objects, but before transparent objects, as render queue index will be 2001 (geometry plus one). This is useful in situations where you want some objects be always drawn between other sets of objects. For example, in most cases transparent water should be drawn after opaque objects but before transparent objects.

+1，累加操作，会让此object绘制在所有opaque绘制后进行；同时在transparent之前； 当你想此object绘制顺序between其他object之间时，此很有用。比如，water在opaque和其他transparent之间绘制的；
Queues up to 2500 (“Geometry+500”) are consided “opaque” and optimize the drawing order of the objects for best performance. Higher rendering queues are considered for “transparent objects” and sort objects by distance, starting rendering from the furthest ones and ending with the closest ones. Skyboxes are drawn in between all opaque and all transparent objects.

天空盒在opaque和transparent之间？？？不应该在background吗？即opaque之前吗？

 

RenderType tag categorizes shaders into several predefined groups, e.g. is is an opaque shader, or an alpha-tested shader etc. This is used by Shader Replacement and in some cases used to produce camera’s depth texture.

If IgnoreProjector tag is given and has a value of “True”, then an object that uses this shader will not be affected by Projectors. This is mostly useful on semitransparent objects, because there is no good way for Projectors to affect them.

以上两句不懂；1.RenderType的作用？是为了分类方便，调用不同类型的shader吗

　　　　　　　　   2.Projector控件的使用。上句英文意思 应该是半透明物体不适合投影效果，如果渲染半透明object，IgnoreProjector设置true；可我对Projector是啥不熟悉，类似渲染到纹理效果吗？

（5） Blend SrcAlpha OneMinusSrcAlpha 

分清楚source和des哦。。。 Source refers to the calculated color, Destination is the color already on the screen. The blend factors are ignored if BlendOp is using logical operations.

http://docs.unity3d.com/Manual/SL-Blend.html

（6）Combine previous * constant DOUBLE, previous * constant

http://docs.unity3d.com/Manual/SL-SetTexture.html

SetTexture [_MainTex] {  
                constantColor [_Color]  
                Combine previous * constant DOUBLE, previous * constant  //rgb，a值；第二个参数为alpha
            }    

和ogl里setTexture类似；具体看文档吧

小Tips：我一直以为这段代码，去掉DOUBLE后，由于_Color是(1,1,1,1)，得到的场景A，和删除此段代码得到场景B是一样的；但结果是A要浅一些；

一直有疑问，后来发现：是我在u3d编辑器把alpha值设置成0.5了；

（7）http://www.jianshu.com/p/7b9498e58659

上博客介绍u3d  shaderLab的比较详细了

5.待解决的疑问；

即黄色的部分；

1.smoothDr是啥？

2.Skyboxes are drawn in between all opaque and all transparent objects.

3.1.RenderType的作用？

4.Projector控件的使用

几个问题都需要实验，估计时间比较久。

Tips，今天看到fog， fog在PS颜色合成之前，操作是：修改片元的颜色，达到雾化效果；是在PS管线内，即所有Test之前进行的

        昨晚mipMap和滤波filter方式又看了下，概念不清晰。