Unity Shader之模板测试

Unity Shader之模板测试

一沙一世界，一花一天堂

一、Stencil testing

 

渲染管线

    当片段着色器处理完一个片段之后，模板测试(Stencil Test)会开始执行，和深度测试一样，它也可能会丢弃片段。接下来，被保留的片段会进入深度测试，它可能会丢弃更多的片段。模板测试是根据又一个缓冲来进行的，它叫做模板缓冲(Stencil Buffer)，我们可以在渲染的时候更新它来获得一些很有意思的效果。
    一个模板缓冲中，（通常）每个模板值(Stencil Value)是8位的。所以每个像素/片段一共能有256种不同的模板值。我们可以将这些模板值设置为我们想要的值，然后当某一个片段有某一个模板值的时候，我们就可以选择丢弃或是保留这个片段了。

 

二、模板函数

2.1 调用函数

1. Stencil 

   ---

2. ｛ 

   ---

3. Ref 1//Reference Value ReadMask 255 WriteMask 255 Comp Always //Comparison Function Pass Replace 

   ---

4. Fail Keep 

   ---

5. ZFail Replace 

   ---

6. ｝ 

   ---

2.2 参数说明

Ref :就是参考值，当参数允许赋值时，会把参考值赋给当前像素
ReadMask: 对当前参考值和已有值进行mask操作，默认值255，一般不用
WriteMask: 写入Mask操作，默认值255，一般不用

Comp: 比较方法。是拿Ref参考值和当前像素缓存上的值进行比较。默认值always，即一直通过。
-- Greater - 大于

• GEqual - 大于等于
• Less - 小于
• LEqual - 小于等于
• Equal - 等于
• NotEqual - 不等于
• Always - 永远通过
• Never - 永远通不过

Pass: 当模版测试和深度测试都通过时，进行处理

Fail :当模版测试和深度测试都失败时，进行处理

ZFail: 当模版测试通过而深度测试失败时，进行处理

pass，Fail，ZFail都属于Stencil操作，他们参数统一如下：

• Keep 保持(即不把参考值赋上去，直接不管)
• Zero 归零
• Replace 替换(拿参考值替代原有值)
• IncrSat 值增加1，但不溢出，如果到255，就不再加
• DecrSat 值减少1，但不溢出，值到0就不再减
• Invert 反转所有位，如果1就会变成254
• IncrWrap 值增加1，会溢出，所以255变成0
• DecrWrap 值减少1，会溢出，所以0变成255

三、案例

3.1 描边

 

渲染管线

 

1. Shader "ShaderCookbook/stencil_outline" { 

   ---

2. Properties { 

   ---

3. _MainTex("Texture", 2D) = "white" {} 

   ---

4. _OutLineWidth("Width", float) = 0.01  

   ---

5. _OutLineColor("Color", color) = (1, 1, 1, 1) 

   ---

6. } 

   ---

7. SubShader { 

   ---

8. Tags { 

   ---

9. "RenderType" = "Opaque" 

   ---

10. } 

    ---

11. LOD 100 

    ---

12.  

    ---

13. Stencil { 

    ---

14. Ref 0 Comp Equal Pass IncrSat 

    ---

15. } 

    ---

16.  

    ---

17. Pass { 

    ---

18. CGPROGRAM 

    ---

19. #pragma vertex vert 

    ---

20. #pragma fragment frag 

    ---

21. #include "UnityCG.cginc" 

    ---

22.  

    ---

23. struct appdata { 

    ---

24. float4 vertex: POSITION; 

    ---

25. float2 uv: TEXCOORD0; 

    ---

26. }; 

    ---

27.  

    ---

28. struct v2f { 

    ---

29. float2 uv: TEXCOORD0; 

    ---

30. float4 vertex: SV_POSITION; 

    ---

31. }; 

    ---

32.  

    ---

33. sampler2D _MainTex; 

    ---

34. float4 _MainTex_ST; 

    ---

35. v2f vert(appdata v) { 

    ---

36. v2f o; 

    ---

37. o.vertex = UnityObjectToClipPos(v.vertex); 

    ---

38. o.uv = TRANSFORM_TEX(v.uv, _MainTex); 

    ---

39. return o; 

    ---

40. } 

    ---

41. fixed4 frag(v2f i) : SV_Target { 

    ---

42. // sample the texture 

    ---

43. fixed4 col = tex2D(_MainTex, i.uv); 

    ---

44. return col; 

    ---

45. } 

    ---

46. ENDCG 

    ---

47. } 

    ---

48.  

    ---

49. Pass { 

    ---

50. CGPROGRAM 

    ---

51. #pragma vertex vert 

    ---

52. #pragma fragment frag 

    ---

53.  

    ---

54. struct appdata { 

    ---

55. float4 vertex: POSITION; 

    ---

56. float4 normal: NORMAL; 

    ---

57. }; 

    ---

58.  

    ---

59. struct v2f { 

    ---

60. float4 vertex: SV_POSITION; 

    ---

61. }; 

    ---

62.  

    ---

63. fixed4 _OutLineColor; 

    ---

64. float _OutLineWidth; 

    ---

65. v2f vert(appdata v) { 

    ---

66. v2f o; 

    ---

67. v.vertex = v.vertex + normalize(v.normal) * _OutLineWidth; 

    ---

68. o.vertex = UnityObjectToClipPos(v.vertex); 

    ---

69. return o; 

    ---

70. } 

    ---

71. fixed4 frag(v2f i) : SV_Target { 

    ---

72. // sample the texture 

    ---

73. fixed4 col = _OutLineColor; 

    ---

74. return col; 

    ---

75. } 

    ---

76. ENDCG 

    ---

77. } 

    ---

78. } 

    ---

79. } 

    ---

3.2 百宝箱

 

渲染管线

 

遮罩层：

1. Shader "ShaderCookbook/StencilEnumMask" 

   ---

2. { 

   ---

3. Properties 

   ---

4. { 

   ---

5. _MainTex ("Texture", 2D) = "white" {} 

   ---

6. [ForceInt] 

   ---

7. _StencilRef("StencilRef",float) = 0 

   ---

8. [Enum(UnityEngine.Rendering.CompareFunction)] 

   ---

9. _StencilComp("StencilComp",int) =0 

   ---

10. [Enum(UnityEngine.Rendering.StencilOp)] 

    ---

11. _StencilOp("StencilOp",int)=0 

    ---

12.  

    ---

13. [ForceInt] 

    ---

14. _StencilReadMask("ReadMask",int)=255 

    ---

15. [ForceInt] 

    ---

16. _StencilWriteMask("WriteMask",int)=255 

    ---

17. [MaterialToggle] 

    ---

18. _ZWrite("zWrite",float)=0 

    ---

19. } 

    ---

20. SubShader 

    ---

21. { 

    ---

22. Tags { "RenderType"="StencilMaskOpaque" 

    ---

23. "Queue" = "Geometry-100" 

    ---

24. "IgnoreProjector" = "True" } 

    ---

25. LOD 100 

    ---

26.  

    ---

27.  

    ---

28. Pass 

    ---

29. { 

    ---

30. ColorMask 0 

    ---

31. ZWrite [_ZWrite] 

    ---

32.  

    ---

33. Stencil{ 

    ---

34. Ref [_StencilRef] 

    ---

35. Comp[_StencilComp] 

    ---

36. Pass[_StencilOp] 

    ---

37. ReadMask[_StencilReadMask] 

    ---

38. WriteMask[_StencilWriteMask] 

    ---

39. } 

    ---

40.  

    ---

41. CGPROGRAM 

    ---

42. #pragma vertex vert 

    ---

43. #pragma fragment frag 

    ---

44. // make fog work 

    ---

45. #pragma multi_compile_fog 

    ---

46. #include "UnityCG.cginc" 

    ---

47.  

    ---

48.  

    ---

49. struct appdata 

    ---

50. { 

    ---

51. float4 vertex : POSITION; 

    ---

52. float2 uv : TEXCOORD0; 

    ---

53. }; 

    ---

54.  

    ---

55. struct v2f 

    ---

56. { 

    ---

57. float2 uv : TEXCOORD0; 

    ---

58. UNITY_FOG_COORDS(1) 

    ---

59. float4 vertex : SV_POSITION; 

    ---

60. }; 

    ---

61.  

    ---

62. sampler2D _MainTex; 

    ---

63. float4 _MainTex_ST; 

    ---

64. v2f vert (appdata v) 

    ---

65. { 

    ---

66. v2f o; 

    ---

67. o.vertex = UnityObjectToClipPos(v.vertex); 

    ---

68. o.uv = TRANSFORM_TEX(v.uv, _MainTex); 

    ---

69. UNITY_TRANSFER_FOG(o,o.vertex); 

    ---

70. return o; 

    ---

71. } 

    ---

72. fixed4 frag (v2f i) : SV_Target 

    ---

73. { 

    ---

74. // sample the texture 

    ---

75. fixed4 col = tex2D(_MainTex, i.uv); 

    ---

76. // apply fog 

    ---

77. UNITY_APPLY_FOG(i.fogCoord, col); 

    ---

78. return col; 

    ---

79. } 

    ---

80. ENDCG 

    ---

81. } 

    ---

82. } 

    ---

83. } 

    ---

显示层：

1.  

   ---

2.  

   ---

3. Shader "ShaderCookbook/StencilEnum" 

   ---

4. { 

   ---

5. Properties 

   ---

6. { 

   ---

7. _MainTex ("Texture", 2D) = "white" {} 

   ---

8. [ForceInt] 

   ---

9. _StencilRef("StencilRef",float) = 0 

   ---

10. [Enum(UnityEngine.Rendering.CompareFunction)] 

    ---

11. _StencilComp("StencilComp",int) =0 

    ---

12. [Enum(UnityEngine.Rendering.StencilOp)] 

    ---

13. _StencilOp("StencilOp",int)=0 

    ---

14.  

    ---

15. [ForceInt] 

    ---

16. _StencilReadMask("ReadMask",int)=255 

    ---

17. [ForceInt] 

    ---

18. _StencilWriteMask("WriteMask",int)=255 

    ---

19. } 

    ---

20. SubShader 

    ---

21. { 

    ---

22. Tags { "RenderType"="opaque" } 

    ---

23. LOD 100 

    ---

24.  

    ---

25.  

    ---

26. Pass 

    ---

27. { 

    ---

28.  

    ---

29. Stencil{ 

    ---

30. Ref [_StencilRef] 

    ---

31. Comp[_StencilComp] 

    ---

32. Pass[_StencilOp] 

    ---

33. ReadMask[_StencilReadMask] 

    ---

34. WriteMask[_StencilWriteMask] 

    ---

35. } 

    ---

36.  

    ---

37. CGPROGRAM 

    ---

38. #pragma vertex vert 

    ---

39. #pragma fragment frag 

    ---

40. // make fog work 

    ---

41. #pragma multi_compile_fog 

    ---

42. #include "UnityCG.cginc" 

    ---

43.  

    ---

44.  

    ---

45. struct appdata 

    ---

46. { 

    ---

47. float4 vertex : POSITION; 

    ---

48. float2 uv : TEXCOORD0; 

    ---

49. }; 

    ---

50.  

    ---

51. struct v2f 

    ---

52. { 

    ---

53. float2 uv : TEXCOORD0; 

    ---

54. UNITY_FOG_COORDS(1) 

    ---

55. float4 vertex : SV_POSITION; 

    ---

56. }; 

    ---

57.  

    ---

58. sampler2D _MainTex; 

    ---

59. float4 _MainTex_ST; 

    ---

60. v2f vert (appdata v) 

    ---

61. { 

    ---

62. v2f o; 

    ---

63. o.vertex = UnityObjectToClipPos(v.vertex); 

    ---

64. o.uv = TRANSFORM_TEX(v.uv, _MainTex); 

    ---

65. UNITY_TRANSFER_FOG(o,o.vertex); 

    ---

66. return o; 

    ---

67. } 

    ---

68. fixed4 frag (v2f i) : SV_Target 

    ---

69. { 

    ---

70. // sample the texture 

    ---

71. fixed4 col = tex2D(_MainTex, i.uv); 

    ---

72. // apply fog 

    ---

73. UNITY_APPLY_FOG(i.fogCoord, col); 

    ---

74. return col; 

    ---

75. } 

    ---

76. ENDCG 

    ---

77. } 

    ---

78. } 

    ---

79. } 

    ---

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