Unity3d之流光效果

using System;
using UnityEngine;

public class WalkLightEffect : MonoBehaviour
{
public Texture MainTex;
public Texture LightTex;
public float Duration;
public float LightULen;
public Vector2 Size;

bool m_play;
float m_timer;
float m_t1;

void Awake()
{
if (MainTex == null)
throw new ArgumentNullException("MainTex");
if (LightTex == null)
throw new ArgumentNullException("LightTex");
if (Duration <= 0)
throw new ArgumentException("Duration");
if (LightULen <= 0 || LightULen >= 1)
throw new ArgumentException("LightULen <= 0 || LightULen >= 1");
if (Size.x <= 0 || Size.y <= 0)
throw new ArgumentException("Size.x <= 0 || Size.y <= 0");

GenerateRenderer();

m_t1 = (1 - LightULen) * Duration;
}

void GenerateRenderer()
{
// Mesh
Mesh mesh = new Mesh();
mesh.vertices = new Vector3[4]
{
new Vector2(-Size.x/2,Size.y/2),
new Vector2(Size.x/2,Size.y/2),
new Vector2(-Size.x/2,-Size.y/2),
new Vector2(Size.x/2,-Size.y/2),
};
mesh.triangles = new int[6] { 0, 1, 2, 2, 1, 3 };
mesh.uv = new Vector2[4]
{
new Vector2(0,1),
new Vector2(1,1),
new Vector2(0,0),
new Vector2(1,0),
};

mesh.Optimize();

var mf = gameObject.AddComponent<MeshFilter>();
mf.mesh = mesh;

// Material
var mat = new Material(Shader.Find("Bleach/WalkLight"));
mat.SetTexture("_MainTex", MainTex);
mat.SetFloat("_LightLen", LightULen);

var mr = gameObject.AddComponent<MeshRenderer>();
mr.sharedMaterial = mat;
}

void Update()
{
if (m_play)
{
renderer.material.SetFloat("_TimeRate", m_timer / Duration);

m_timer += Time.deltaTime;

if (m_timer > Duration)
m_timer = 0;
else if (m_timer > m_t1)
renderer.material.SetFloat("_ReachBoundary", 1);
else
renderer.material.SetFloat("_ReachBoundary", -1);
}
}

public bool Play
{
set
{
renderer.material.SetTexture("_LightTex", value ? LightTex : null);
m_timer = 0;
m_play = value;
}
}
}

Shader "Bleach/WalkLight"
{
Properties
{
_MainTex ("Main", 2D) = "white" {}
_LightTex("Light", 2D) = "black" {}
_LightLen("Light Length", float) = 0
}

SubShader
{
Pass
{
Tags { "RenderType"="Opaque" }
LOD 200

Cull Off

CGPROGRAM
#pragma vertex vert
#pragma fragment frag

uniform sampler2D _MainTex;
uniform sampler2D _LightTex;
uniform    fixed _LightLen;

uniform fixed _ReachBoundary;     // 小于0表示未到边界，大于0表示到达边界
uniform fixed _TimeRate;        // 时间/周期

struct Data
{
fixed4 vertex:POSITION;
fixed2 texcoord:TEXCOORD0;
};

struct V2F
{
fixed4 pos:SV_POSITION;
fixed2 uv:TEXCOORD0;
};

V2F vert(Data v)
{
V2F o;
o.pos=mul(UNITY_MATRIX_MVP,v.vertex);
o.uv=v.texcoord;
return o;
}

fixed4 frag(V2F i):COLOR
{
fixed4 main = tex2D(_MainTex,i.uv);
fixed x = _ReachBoundary>0 && i.uv.x<_LightLen? i.uv.x+1 : i.uv.x;
fixed lightU = (x - _TimeRate)/_LightLen;            // u=(x-timer/Duration)/_LightLen;
fixed4 light = tex2D(_LightTex,float2(lightU,i.uv.y));

return lerp(main,light,light.a);
}

ENDCG
}
}

FallBack "Diffuse"
}