Unity3D 实现雪花飘飞效果[Shader]（三）

Cici_coach

     今天为大家分享一下，如何写一个雪花效果的Shader，因为操作过程比较简单，我直接上代码啦！
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    1.新建一个unity3d 项目，新建一个CameraFilterPack_Atmosphere_Snow_8bits.shader文件。

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1. Shader "CameraFilterPack/Atmosphere_Snow_8bits" {
   
2. Properties
   
3. {
   
4. _MainTex ("Base (RGB)", 2D) = "white" {}
   
5. _TimeX ("Time", Range(0.0, 1.0)) = 1.0
   
6. _ScreenResolution ("_ScreenResolution", Vector) = (0.,0.,0.,0.)
   
7. }
   
8. SubShader
   
9. {
   
10. Pass
    
11. {
    
12. ZTest Always
    
13. CGPROGRAM
    
14. #pragma vertex vert
    
15. #pragma fragment frag
    
16. #pragma fragmentoption ARB_precision_hint_fastest
    
17. #pragma target 3.0
    
18. #pragma glsl
    
19. #include "UnityCG.cginc"
    
20. uniform sampler2D _MainTex;
    
21. uniform float _TimeX;
    
22. uniform float _Value;
    
23. uniform float _Value2;
    
24. uniform float4 _ScreenResolution;
    
25. uniform float2 _MainTex_TexelSize;
    
26. struct appdata_t
    
27. {
    
28. float4 vertex   : POSITION;
    
29. float4 color    : COLOR;
    
30. float2 texcoord : TEXCOORD0;
    
31. };
    
32. struct v2f
    
33. {
    
34. half2 texcoord  : TEXCOORD0;
    
35. float4 vertex   : SV_POSITION;
    
36. fixed4 color    : COLOR;
    
37. };
    
38. v2f vert(appdata_t IN)
    
39. {
    
40. v2f OUT;
    
41. OUT.vertex = mul(UNITY_MATRIX_MVP, IN.vertex);
    
42. OUT.texcoord = IN.texcoord;
    
43. OUT.color = IN.color;
    
44. return OUT;
    
45. }
    
46. 
    
47. inline float2 mod(float2 x,float2 modu) {
    
48.   return x - floor(x * (1.0 / modu)) * modu;
    
49. }
    
50. 
    
51. 
    
52. inline float rand(float2 co)
    
53. {
    
54.         float r;
    
55.         co = floor(co*_Value2);
    
56.         r = frac(sin(dot(co.xy,float2(12.9898,78.233))) * 43758.5453);
    
57.    return r;
    
58. }
    
59. 
    
60. float4 frag (v2f i) : COLOR
    
61. {
    
62.         float2 uv = i.texcoord.xy;
    
63.        
    
64.     float3 col=tex2D(_MainTex,uv).rgb;
    
65.         #if UNITY_UV_STARTS_AT_TOP
    
66. if (_MainTex_TexelSize.y < 0)
    
67. uv.y = 1-uv.y;
    
68. #endif
    
69.    float ts=uv.y-.2+sin(uv.x*4.0+7.4*cos(uv.x*10.0))*0.005;
    
70. 
    
71.     uv*=2.0;
    
72.    
    
73.     float c=cos(8*0.01),si=sin(8*0.01);
    
74.         uv=(uv-0.5)*float2(c+si,-si+c);       
    
75.    
    
76.     float s=rand(mod(uv * 1.01 +float2(_TimeX,_TimeX)*float2(0.02,0.501),1.0)).r;
    
77.     col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.9,1.0, s * .9 * _Value));
    
78.    
    
79.         s=rand(mod(uv * 1.07 +float2(_TimeX,_TimeX)*float2(0.02,0.501),1.0)).r;
    
80.         col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.9,1.0, s * 1. * _Value));
    
81.    
    
82.         s=rand(mod(uv+float2(_TimeX,_TimeX)*float2(0.05,0.5),1.0)).r;
    
83.     col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.9,1.0, s * .98 * _Value));
    
84.        
    
85.         s=rand(mod(uv * .9 +float2(_TimeX,_TimeX)*float2(0.02,0.51),1.0)).r;
    
86.     col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.9,1.0, s * .99 * _Value));
    
87.        
    
88.         s=rand(mod(uv * .75 +float2(_TimeX,_TimeX)*float2(0.07,0.493),1.0)).r;
    
89.     col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.9,1.0, s * 1. * _Value));
    
90.        
    
91.         s=rand(mod(uv * .5 +float2(_TimeX,_TimeX)*float2(0.03,0.504),1.0)).r;
    
92.     col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.94,1.0, s * 1. * _Value));
    
93.        
    
94.         s=rand(mod(uv * .3 +float2(_TimeX,_TimeX)*float2(0.02,0.497),1.0)).r;
    
95.     col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.95,1.0, s * 1. * _Value));
    
96.        
    
97.         s=rand(mod(uv * .1 +float2(_TimeX,_TimeX)*float2(0.0,0.51),1.0)).r;
    
98.         col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.96,1.0, s * 1. * _Value));
    
99.        
    
100.         s=rand(mod(uv * .03 +float2(_TimeX,_TimeX)*float2(0.0,0.523),1.0)).r;
     
101.         col=lerp(col,float3(1.0,1.0,1.0),smoothstep(0.99,1.0, s * 1. * _Value));
     
102.    
     
103.         return  float4(col,1.0);
     
104. }
     
105. ENDCG
     
106. }
     
107. }
     
108. }

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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。

1. using UnityEngine;
   
2. using System.Collections;
   
3. [ExecuteInEditMode]
   
4. [AddComponentMenu ("Camera Filter Pack/Pixel/Snow_8bits")]
   
5. public class CameraFilterPack_Atmosphere_Snow_8bits : MonoBehaviour {
   
6. #region Variables
   
7. public Shader SCShader;
   
8. private float TimeX = 1.0f;
   
9. private Vector4 ScreenResolution;
   
10. private Material SCMaterial;
    
11. [Range(0.9f, 2f)]
    
12. public float Threshold = 1f;
    
13. [Range(8f, 256f)]
    
14. public float Size = 64f;
    
15. [Range(0f, 10f)]
    
16. private float Value3 = 1f;
    
17. [Range(0f, 10f)]
    
18. private float Value4 = 1f;
    
19. public static float ChangeValue;
    
20. public static float ChangeValue2;
    
21. public static float ChangeValue3;
    
22. public static float ChangeValue4;
    
23. #endregion
    
24. #region Properties
    
25. Material material
    
26. {
    
27. get
    
28. {
    
29. if(SCMaterial == null)
    
30. {
    
31. SCMaterial = new Material(SCShader);
    
32. SCMaterial.hideFlags = HideFlags.HideAndDontSave;
    
33. }
    
34. return SCMaterial;
    
35. }
    
36. }
    
37. #endregion
    
38. void Start ()
    
39. {
    
40. ChangeValue = Threshold;
    
41. ChangeValue2 = Size;
    
42. ChangeValue3 = Value3;
    
43. ChangeValue4 = Value4;
    
44. SCShader = Shader.Find("CameraFilterPack/Atmosphere_Snow_8bits");
    
45. if(!SystemInfo.supportsImageEffects)
    
46. {
    
47. enabled = false;
    
48. return;
    
49. }
    
50. }
    
51. 
    
52. void OnRenderImage (RenderTexture sourceTexture, RenderTexture destTexture)
    
53. {
    
54. if(SCShader != null)
    
55. {
    
56. TimeX+=Time.deltaTime;
    
57. if (TimeX>100)  TimeX=0;
    
58. material.SetFloat("_TimeX", TimeX);
    
59. material.SetFloat("_Value", Threshold);
    
60. material.SetFloat("_Value2", Size);
    
61. material.SetFloat("_Value3", Value3);
    
62. material.SetFloat("_Value4", Value4);
    
63. material.SetVector("_ScreenResolution",new Vector4(sourceTexture.width,sourceTexture.height,0.0f,0.0f));
    
64. Graphics.Blit(sourceTexture, destTexture, material);
    
65. }
    
66. else
    
67. {
    
68. Graphics.Blit(sourceTexture, destTexture);
    
69. }
    
70. }
    
71. void OnValidate()
    
72. {
    
73.                 ChangeValue=Threshold;
    
74.                 ChangeValue2=Size;
    
75.                 ChangeValue3=Value3;
    
76.                 ChangeValue4=Value4;
    
77. }
    
78. void Update ()
    
79. {
    
80. if (Application.isPlaying)
    
81. {
    
82. Threshold = ChangeValue;
    
83. Size = ChangeValue2;
    
84. Value3 = ChangeValue3;
    
85. Value4 = ChangeValue4;
    
86. }
    
87. #if UNITY_EDITOR
    
88. if (Application.isPlaying!=true)
    
89. {
    
90. SCShader = Shader.Find("CameraFilterPack/Atmosphere_Snow_8bits");
    
91. }
    
92. #endif
    
93. }
    
94. void OnDisable ()
    
95. {
    
96. if(SCMaterial)
    
97. {
    
98. DestroyImmediate(SCMaterial);
    
99. }
    
100. }
     
101. }
     

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

1. using UnityEngine;
   
2. 
   
3. public class AddCameraFilter : MonoBehaviour {
   
4. 
   
5.     private CameraFilterPack_Atmosphere_Snow_8bits _cameraFilterPack;
   
6.     // Use this for initialization
   
7.     void Start()
   
8.     {
   
9.         _cameraFilterPack = GetComponent<CameraFilterPack_Atmosphere_Snow_8bits>();
   
10.     }
    
11. 
    
12.     // Update is called once per frame
    
13.     void OnGUI()
    
14.     {
    
15. 
    
16.         if (GUI.Button(new Rect(50, 200, 200, 30), "添加雪花效果"))
    
17.         {
    
18.             if (_cameraFilterPack == null)
    
19.                 _cameraFilterPack = gameObject.AddComponent<CameraFilterPack_Atmosphere_Snow_8bits>();
    
20.             if (_cameraFilterPack != null)
    
21.                 _cameraFilterPack.enabled = true;
    
22.         }
    
23.         if (GUI.Button(new Rect(50, 250, 200, 30), "移除雪花效果"))
    
24.         {
    
25.             if (_cameraFilterPack != null)
    
26.                 _cameraFilterPack.enabled = false;
    
27.         }
    
28.     }
    
29. }
    

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4.好吧！最后我们直接运行项目看效果噢！



   
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