Unity入门精要（十一）让画面动起来 - Shader入门精要 - 渲染管线 - 游戏开发

# UnityShader 的内置时间变量

通过使用 Time 实现循环的特效播放。

	Shader "Unlit/Exp2Shader"
	{
	Properties
	{
	_Color ("Color Tint",Color)=(1,1,1,1)
	_MainTex ("Texture", 2D) = "white" {}

	_HorizontalAmount("Horizontal Amount",Float)=4
	_VerticalAmount("Vertical Amount",Float)=4
	_Speed("Speed",Range(1,100))=30
	}
	SubShader
	{
	Tags
	{
	"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"
	}

	Pass
	{
	CGPROGRAM
	#pragma vertex vert
	#pragma fragment frag
	// make fog work
	#pragma multi_compile_fog

	#include "UnityCG.cginc"

	struct appdata
	{
	float4 vertex : POSITION;
	float2 uv : TEXCOORD0;
	};

	struct v2f
	{
	float2 uv : TEXCOORD0;
	float4 vertex : SV_POSITION;
	};

	sampler2D _MainTex;
	float4 _MainTex_ST;

	v2f vert(appdata v)
	{
	v2f o;
	o.vertex = UnityObjectToClipPos(v.vertex);
	o.uv = TRANSFORM_TEX(v.uv, _MainTex);
	return o;
	}

	float _Speed;
	float _HorizontalAmount, _VerticalAmount;
	fixed4 _Color;
	fixed4 frag(v2f i) : SV_Target
	{
	float time = floor(_Time.y * _Speed);
	float row = floor(time / _HorizontalAmount);
	float column = time - row * _VerticalAmount;

	half2 uv = i.uv + half2(column, -row);
	uv.x /= _HorizontalAmount;
	uv.y /= _VerticalAmount;

	fixed4 c = tex2D(_MainTex, uv);
	c.rgb *= _Color;

	return c;
	}
	ENDCG
	}
	} Fallback "Transparent/VertexLit"

	}

很多无限滚动的背景也是使用了纹理动画。纹理资源： OpenGameArt.org

注意： uv 现已经不存在 zw 值。

	Shader "Unlit/BackGroundShader"
	{
	Properties
	{
	_MainTex ("Texture", 2D) = "white" {}
	_DetailTex("2nd Layer (RGB)",2D)="white" {}
	_ScrollX("Base Layer Scrool Speed",Float)=1.0
	_Scroll2X("2nd Layer Scroll Speed",Float)=1.0
	_Multiplier("Layer Multiplier",Float)=1
	}
	SubShader
	{
	Tags
	{
	"RenderType"="Opaque"
	}
	LOD 100

	Pass
	{
	CGPROGRAM
	#pragma vertex vert
	#pragma fragment frag
	// make fog work
	#pragma multi_compile_fog

	#include "UnityCG.cginc"

	struct appdata
	{
	float4 vertex : POSITION;
	float2 uv : TEXCOORD0;
	};

	struct v2f
	{
	float2 uv : TEXCOORD0;
	UNITY_FOG_COORDS(1)
	float4 vertex : SV_POSITION;
	};

	sampler2D _MainTex, _DetailTex;
	float4 _MainTex_ST;
	float _ScrollX, _Scroll2X, _Multiplier;
	float4 _DetailTex_ST;

	v2f vert(appdata v)
	{
	v2f o;
	o.vertex = UnityObjectToClipPos(v.vertex);
	o.uv.xy = TRANSFORM_TEX(v.uv, _MainTex) + frac(float2(_ScrollX, 0.0) * _Time.y);
	o.uv.zw = TRANSFORM_TEX(v.uv, _DetailTex) + frac(float2(_Scroll2X, 0.0) * _Time.y);
	UNITY_TRANSFER_FOG(o, o.vertex);
	return o;
	}

	fixed4 frag(v2f i) : SV_Target
	{
	fixed4 firstLayer = tex2D(_MainTex, i.uv.xy);
	fixed4 secondLayer = tex2D(_DetailTex, i.uv.zw);

	fixed4 c = lerp(firstLayer, secondLayer, secondLayer.a);
	c.rgb *= _Multiplier;

	return c;
	}
	ENDCG
	}
	}
	Fallback "VertexLit"
	}