Unity Shader之模板測試

Unity Shader之模板測試

一沙一世界，一花一天堂

一、Stencil testing

 

渲染管線

    當片段着色器處理完一個片段之後，模板測試(Stencil Test)會開始執行，和深度測試一樣，它也可能會丟棄片段。接下來，被保留的片段會進入深度測試，它可能會丟棄更多的片段。模板測試是根據又一個緩衝來進行的，它叫做模板緩衝(Stencil Buffer)，我們可以在渲染的時候更新它來獲得一些很有意思的效果。
    一個模板緩衝中，（通常）每個模板值(Stencil Value)是8位的。所以每個像素/片段一共能有256種不同的模板值。我們可以將這些模板值設置爲我們想要的值，然後當某一個片段有某一個模板值的時候，我們就可以選擇丟棄或是保留這個片段了。

 

二、模板函數

2.1 調用函數

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 參數說明

Ref :就是參考值，當參數允許賦值時，會把參考值賦給當前像素
ReadMask: 對當前參考值和已有值進行mask操作，默認值255，一般不用
WriteMask: 寫入Mask操作，默認值255，一般不用

Comp: 比較方法。是拿Ref參考值和當前像素緩存上的值進行比較。默認值always，即一直通過。
-- Greater - 大於

• GEqual - 大於等於
• Less - 小於
• LEqual - 小於等於
• Equal - 等於
• NotEqual - 不等於
• Always - 永遠通過
• Never - 永遠通不過

Pass: 當模版測試和深度測試都通過時，進行處理

Fail :當模版測試和深度測試都失敗時，進行處理

ZFail: 當模版測試通過而深度測試失敗時，進行處理

pass，Fail，ZFail都屬於Stencil操作，他們參數統一如下：

• Keep 保持(即不把參考值賦上去，直接不管)
• Zero 歸零
• Replace 替換(拿參考值替代原有值)
• IncrSat 值增加1，但不溢出，如果到255，就不再加
• DecrSat 值減少1，但不溢出，值到0就不再減
• Invert 反轉所有位，如果1就會變成254
• IncrWrap 值增加1，會溢出，所以255變成0
• DecrWrap 值減少1，會溢出，所以0變成255

三、案例

3.1 描邊

 

渲染管線

 

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 百寶箱

 

渲染管線

 

遮罩層：

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. } 

    ---

顯示層：

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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