Unity3D 实现雪花飘飞效果[Shader]

2017-01-06

为大家分享一下，如何写一个雪花效果的Shader，因为操作过程比较简单，直接上代码！

1.新建一个unity3d 项目，新建一个CameraFilterPack_Atmosphere_Snow_8bits.shader文件。

Shader "CameraFilterPack/Atmosphere_Snow_8bits" {
Properties
{
_MainTex ("Base (RGB)", 2D) = "white" {}
_TimeX ("Time", Range(0.0, 1.0)) = 1.0
_ScreenResolution ("_ScreenResolution", Vector) = (0.,0.,0.,0.)
}
SubShader
{
Pass
{
ZTest Always
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest
#pragma target 3.0
#pragma glsl
#include "UnityCG.cginc"
uniform sampler2D _MainTex;
uniform float _TimeX;
uniform float _Value;
uniform float _Value2;
uniform float4 _ScreenResolution;
uniform float2 _MainTex_TexelSize;
struct appdata_t
{
float4 vertex : POSITION;
float4 color : COLOR;
float2 texcoord : TEXCOORD0;
};
struct v2f
{
half2 texcoord : TEXCOORD0;
float4 vertex : SV_POSITION;
fixed4 color : COLOR;
};
v2f vert(appdata_t IN)
{
v2f OUT;
OUT.vertex = mul(UNITY_MATRIX_MVP, IN.vertex);
OUT.texcoord = IN.texcoord;
OUT.color = IN.color;
return OUT;
}
inline float2 mod(float2 x,float2 modu) {
return x - floor(x * (1.0 / modu)) * modu;
}
inline float rand(float2 co)
{
float r;
co = floor(co*_Value2);
r = frac(sin(dot(co.xy,float2(12.9898,78.233))) * 43758.5453);
return r;
}
float4 frag (v2f i) : COLOR
{
float2 uv = i.texcoord.xy;
float3 col=tex2D(_MainTex,uv).rgb;
#if UNITY_UV_STARTS_AT_TOP
if (_MainTex_TexelSize.y < 0)
uv.y = 1-uv.y;
#endif
float ts=uv.y-.2+sin(uv.x*4.0+7.4*cos(uv.x*10.0))*0.005;
uv*=2.0;
float c=cos(8*0.01),si=sin(8*0.01);
uv=(uv-0.5)*float2(c+si,-si+c);
float s=rand(mod(uv * 1.01 +float2(_TimeX,_TimeX)*float2(0.02,0.501),1.0)).r;
col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.9,1.0, s * .9 * _Value));
s=rand(mod(uv * 1.07 +float2(_TimeX,_TimeX)*float2(0.02,0.501),1.0)).r;
col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.9,1.0, s * 1. * _Value));
s=rand(mod(uv+float2(_TimeX,_TimeX)*float2(0.05,0.5),1.0)).r;
col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.9,1.0, s * .98 * _Value));
s=rand(mod(uv * .9 +float2(_TimeX,_TimeX)*float2(0.02,0.51),1.0)).r;
col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.9,1.0, s * .99 * _Value));
s=rand(mod(uv * .75 +float2(_TimeX,_TimeX)*float2(0.07,0.493),1.0)).r;
col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.9,1.0, s * 1. * _Value));
s=rand(mod(uv * .5 +float2(_TimeX,_TimeX)*float2(0.03,0.504),1.0)).r;
col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.94,1.0, s * 1. * _Value));
s=rand(mod(uv * .3 +float2(_TimeX,_TimeX)*float2(0.02,0.497),1.0)).r;
col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.95,1.0, s * 1. * _Value));
s=rand(mod(uv * .1 +float2(_TimeX,_TimeX)*float2(0.0,0.51),1.0)).r;
col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.96,1.0, s * 1. * _Value));
s=rand(mod(uv * .03 +float2(_TimeX,_TimeX)*float2(0.0,0.523),1.0)).r;
col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.99,1.0, s * 1. * _Value));
return float4(col,1.0);
}
ENDCG
}
}
}

复制代码

2.为了方便更改shader的一些参数，所以我们新建一个CameraFilterPack_Atmosphere_Snow_8bits.cs 组件类。

using UnityEngine;
using System.Collections;
[ExecuteInEditMode]
[AddComponentMenu ("Camera Filter Pack/Pixel/Snow_8bits")]
public class CameraFilterPack_Atmosphere_Snow_8bits : MonoBehaviour {
#region Variables
public Shader SCShader;
private float TimeX = 1.0f;
private Vector4 ScreenResolution;
private Material SCMaterial;
[Range(0.9f, 2f)]
public float Threshold = 1f;
[Range(8f, 256f)]
public float Size = 64f;
[Range(0f, 10f)]
private float Value3 = 1f;
[Range(0f, 10f)]
private float Value4 = 1f;
public static float ChangeValue;
public static float ChangeValue2;
public static float ChangeValue3;
public static float ChangeValue4;
#endregion
#region Properties
Material material
{
get
{
if(SCMaterial == null)
{
SCMaterial = new Material(SCShader);
SCMaterial.hideFlags = HideFlags.HideAndDontSave;
}
return SCMaterial;
}
}
#endregion
void Start ()
{
ChangeValue = Threshold;
ChangeValue2 = Size;
ChangeValue3 = Value3;
ChangeValue4 = Value4;
SCShader = Shader.Find("CameraFilterPack/Atmosphere_Snow_8bits");
if(!SystemInfo.supportsImageEffects)
{
enabled = false;
return;
}
}
void OnRenderImage (RenderTexture sourceTexture, RenderTexture destTexture)
{
if(SCShader != null)
{
TimeX+=Time.deltaTime;
if (TimeX>100) TimeX=0;
material.SetFloat("_TimeX", TimeX);
material.SetFloat("_Value", Threshold);
material.SetFloat("_Value2", Size);
material.SetFloat("_Value3", Value3);
material.SetFloat("_Value4", Value4);
material.SetVector("_ScreenResolution",new Vector4(sourceTexture.width,sourceTexture.height,0.0f,0.0f));
Graphics.Blit(sourceTexture, destTexture, material);
}
else
{
Graphics.Blit(sourceTexture, destTexture);
}
}
void OnValidate()
{
ChangeValue=Threshold;
ChangeValue2=Size;
ChangeValue3=Value3;
ChangeValue4=Value4;
}
void Update ()
{
if (Application.isPlaying)
{
Threshold = ChangeValue;
Size = ChangeValue2;
Value3 = ChangeValue3;
Value4 = ChangeValue4;
}
#if UNITY_EDITOR
if (Application.isPlaying!=true)
{
SCShader = Shader.Find("CameraFilterPack/Atmosphere_Snow_8bits");
}
#endif
}
void OnDisable ()
{
if(SCMaterial)
{
DestroyImmediate(SCMaterial);
}
}
}

复制代码

3.在摄像机上附加AddCameraFilter.cs组件，为了方便控制看出效果。

using UnityEngine;
public class AddCameraFilter : MonoBehaviour {
private CameraFilterPack_Atmosphere_Snow_8bits _cameraFilterPack;
// Use this for initialization
void Start()
{
_cameraFilterPack = GetComponent<CameraFilterPack_Atmosphere_Snow_8bits>();
}
// Update is called once per frame
void OnGUI()
{
if (GUI.Button(new Rect(50, 200, 200, 30), "添加雪花效果"))
{
if (_cameraFilterPack == null)
_cameraFilterPack = gameObject.AddComponent<CameraFilterPack_Atmosphere_Snow_8bits>();
if (_cameraFilterPack != null)
_cameraFilterPack.enabled = true;
}
if (GUI.Button(new Rect(50, 250, 200, 30), "移除雪花效果"))
{
if (_cameraFilterPack != null)
_cameraFilterPack.enabled = false;
}
}
}