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SnowTessellation.hlsl

Jul 8th, 2022
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  1. //#ifndef TESSELLATION_CGINC_INCLUDED
  2. //#define TESSELLATION_CGINC_INCLUDED
  3. #if defined(SHADER_API_D3D11) || defined(SHADER_API_GLES3) || defined(SHADER_API_GLCORE) || defined(SHADER_API_VULKAN) || defined(SHADER_API_METAL) || defined(SHADER_API_PSSL)
  4.     #define UNITY_CAN_COMPILE_TESSELLATION 1
  5.     #   define UNITY_domain                 domain
  6.     #   define UNITY_partitioning           partitioning
  7.     #   define UNITY_outputtopology         outputtopology
  8.     #   define UNITY_patchconstantfunc      patchconstantfunc
  9.     #   define UNITY_outputcontrolpoints    outputcontrolpoints
  10. #endif
  11.  
  12. struct Varyings
  13. {      
  14.     float3 worldPos : TEXCOORD1;
  15.     float3 normal : NORMAL;
  16.     float4 vertex : SV_POSITION;
  17.     float2 uv : TEXCOORD0;
  18.     float3 viewDir : TEXCOORD3;
  19.     float fogFactor : TEXCOORD4;
  20. };
  21.  
  22. float _Tess;
  23. float _MaxTessDistance;
  24. float _Fade;
  25.  
  26. struct TessellationFactors
  27. {
  28.     float edge[3] : SV_TessFactor;
  29.     float inside : SV_InsideTessFactor;
  30. };
  31.  
  32. struct Attributes
  33. {
  34.     float4 vertex : POSITION;
  35.     float3 normal : NORMAL;
  36.     float2 uv : TEXCOORD0;    
  37. };
  38.  
  39. struct ControlPoint
  40. {
  41.     float4 vertex : INTERNALTESSPOS;
  42.     float2 uv : TEXCOORD0;
  43.     float3 normal : NORMAL;  
  44. };
  45.  
  46. [UNITY_domain("tri")]
  47. [UNITY_outputcontrolpoints(3)]
  48. [UNITY_outputtopology("triangle_cw")]
  49. [UNITY_partitioning("fractional_odd")]
  50. [UNITY_patchconstantfunc("patchConstantFunction")]
  51. ControlPoint hull(InputPatch<ControlPoint, 3> patch, uint id : SV_OutputControlPointID)
  52. {
  53.     return patch[id];
  54. }
  55.  
  56. TessellationFactors UnityCalcTriEdgeTessFactors (float3 triVertexFactors)
  57. {
  58.     TessellationFactors tess;
  59.     tess.edge[0] = 0.5 * (triVertexFactors.y + triVertexFactors.z);
  60.     tess.edge[1] = 0.5 * (triVertexFactors.x + triVertexFactors.z);
  61.     tess.edge[2] = 0.5 * (triVertexFactors.x + triVertexFactors.y);
  62.     tess.inside = (triVertexFactors.x + triVertexFactors.y + triVertexFactors.z) / 3.0f;
  63.     return tess;
  64. }
  65.  
  66. float CalcDistanceTessFactor(float4 vertex, float minDist, float maxDist, float tess)
  67. {
  68.                 float3 worldPosition = mul(unity_ObjectToWorld, vertex).xyz;
  69.                 float dist = distance(worldPosition, _WorldSpaceCameraPos);
  70.                 float f = clamp(1.0 - (dist - minDist) / (maxDist - minDist), 0.01, 1.0);
  71.                 return f * tess;
  72. }
  73.  
  74. TessellationFactors DistanceBasedTess(float4 v0, float4 v1, float4 v2, float minDist, float maxDist, float tess)
  75. {
  76.                 float3 f;
  77.                 f.x = CalcDistanceTessFactor(v0, minDist, maxDist, tess);
  78.                 f.y = CalcDistanceTessFactor(v1, minDist, maxDist, tess);
  79.                 f.z = CalcDistanceTessFactor(v2, minDist, maxDist, tess);
  80.  
  81.                 return UnityCalcTriEdgeTessFactors(f);
  82. }
  83.  
  84. uniform float3 _Position;
  85. uniform sampler2D _GlobalEffectRT;
  86. uniform float _OrthographicCamSize;
  87.  
  88. sampler2D  _Noise;
  89. float _NoiseScale, _SnowHeight, _NoiseWeight, _SnowDepth;
  90.  
  91. TessellationFactors patchConstantFunction(InputPatch<ControlPoint, 3> patch)
  92. {
  93.     float minDist = 2.0;
  94.     float maxDist = _MaxTessDistance;
  95.     TessellationFactors f;
  96.     return DistanceBasedTess(patch[0].vertex, patch[1].vertex, patch[2].vertex, minDist, maxDist, _Tess);
  97.    
  98. }
  99.  
  100. float4 GetShadowPositionHClip(Attributes input)
  101. {
  102.     float3 positionWS = TransformObjectToWorld(input.vertex.xyz);
  103.     float3 normalWS = TransformObjectToWorldNormal(input.normal);
  104.  
  105.     float4 positionCS = TransformWorldToHClip(ApplyShadowBias(positionWS, normalWS, 0));
  106.  
  107. #if UNITY_REVERSED_Z
  108.     positionCS.z = min(positionCS.z, positionCS.w * UNITY_NEAR_CLIP_VALUE);
  109. #else
  110.     positionCS.z = max(positionCS.z, positionCS.w * UNITY_NEAR_CLIP_VALUE);
  111. #endif
  112.     return positionCS;
  113. }
  114.  
  115. Varyings vert(Attributes input)
  116. {
  117.     Varyings output;
  118.    
  119.     float3 worldPosition = mul(unity_ObjectToWorld, input.vertex).xyz;
  120.     //create local uv
  121.     float2 uv = worldPosition.xz - _Position.xz;
  122.     uv = uv / (_OrthographicCamSize * 2);
  123.     uv += 0.5;
  124.    
  125.     // Effects RenderTexture Reading
  126.     float4 RTEffect = tex2Dlod(_GlobalEffectRT, float4(uv, 0, 0));
  127.     // smoothstep to prevent bleeding
  128.     RTEffect *=  smoothstep(0.99, _Fade, uv.x) * smoothstep(0.99, _Fade,1- uv.x);
  129.     RTEffect *=  smoothstep(0.99, _Fade, uv.y) * smoothstep(0.99, _Fade,1- uv.y);
  130.    
  131.     // worldspace noise texture
  132.     float SnowNoise = tex2Dlod(_Noise, float4(worldPosition.xz * _NoiseScale, 0, 0)).r;
  133.     output.viewDir = SafeNormalize(GetCameraPositionWS() - worldPosition);
  134.  
  135.     // move vertices up where snow is
  136.     input.vertex.xyz += SafeNormalize(input.normal) * saturate(( _SnowHeight) + (SnowNoise * _NoiseWeight)) * saturate(1-(RTEffect.g * _SnowDepth));
  137.  
  138.     // transform to clip space
  139.     #ifdef SHADERPASS_SHADOWCASTER
  140.         output.vertex = GetShadowPositionHClip(input);
  141.     #else
  142.         output.vertex = TransformObjectToHClip(input.vertex.xyz);
  143.     #endif
  144.  
  145.     //outputs
  146.     output.worldPos =  mul(unity_ObjectToWorld, input.vertex).xyz;
  147.     output.normal = input.normal;
  148.     output.uv = input.uv;
  149.     output.fogFactor = ComputeFogFactor(output.vertex.z);
  150.     return output;
  151. }
  152.  
  153. [UNITY_domain("tri")]
  154. Varyings domain(TessellationFactors factors, OutputPatch<ControlPoint, 3> patch, float3 barycentricCoordinates : SV_DomainLocation)
  155. {
  156.     Attributes v;
  157.    
  158.     #define Interpolate(fieldName) v.fieldName = \
  159.                 patch[0].fieldName * barycentricCoordinates.x + \
  160.                 patch[1].fieldName * barycentricCoordinates.y + \
  161.                 patch[2].fieldName * barycentricCoordinates.z;
  162.  
  163.     Interpolate(vertex)
  164.     Interpolate(uv)
  165.     Interpolate(normal)
  166.    
  167.     return vert(v);
  168. }
  169.  
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