Dynamic Snow

Shader "Custom/Dynamic_Snow" {
    Properties {
        _SnowTexture ("SnowTexture", 2D) = "white" {}
        _SnowAmount ("Snow Amount", Range(0, 3)) = 0
        _MainTexture ("Main Texture", 2D) = "white" {}
        _NormalMap ("Normal Map", 2D) = "black" {}
    }
    SubShader {
        Tags {
            "Queue"="Geometry+1"
            "RenderType"="Opaque"
        }
        Pass {
            Name "FORWARD"
            Tags {
                "LightMode"="ForwardBase"
            }
            ZTest Always


            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #define SHOULD_SAMPLE_SH ( defined (LIGHTMAP_OFF) && defined(DYNAMICLIGHTMAP_OFF) )
            #define _GLOSSYENV 1
            #include "UnityCG.cginc"
            #include "AutoLight.cginc"
            #include "Lighting.cginc"
            #include "UnityPBSLighting.cginc"
            #include "UnityStandardBRDF.cginc"
            #pragma multi_compile_fwdbase_fullshadows
            #pragma multi_compile LIGHTMAP_OFF LIGHTMAP_ON
            #pragma multi_compile DIRLIGHTMAP_OFF DIRLIGHTMAP_COMBINED DIRLIGHTMAP_SEPARATE
            #pragma multi_compile DYNAMICLIGHTMAP_OFF DYNAMICLIGHTMAP_ON
            #pragma only_renderers d3d9 d3d11 glcore gles
            #pragma target 3.0
            uniform sampler2D _SnowTexture; uniform float4 _SnowTexture_ST;
            uniform float _SnowAmount;
            uniform sampler2D _MainTexture; uniform float4 _MainTexture_ST;
            uniform sampler2D _NormalMap; uniform float4 _NormalMap_ST;
            struct VertexInput {
                float4 vertex : POSITION;
                float3 normal : NORMAL;
                float4 tangent : TANGENT;
                float2 texcoord0 : TEXCOORD0;
                float2 texcoord1 : TEXCOORD1;
                float2 texcoord2 : TEXCOORD2;
            };
            struct VertexOutput {
                float4 pos : SV_POSITION;
                float2 uv0 : TEXCOORD0;
                float2 uv1 : TEXCOORD1;
                float2 uv2 : TEXCOORD2;
                float4 posWorld : TEXCOORD3;
                float3 normalDir : TEXCOORD4;
                float3 tangentDir : TEXCOORD5;
                float3 bitangentDir : TEXCOORD6;
                LIGHTING_COORDS(7,8)
                #if defined(LIGHTMAP_ON) || defined(UNITY_SHOULD_SAMPLE_SH)
                    float4 ambientOrLightmapUV : TEXCOORD9;
                #endif
            };
            VertexOutput vert (VertexInput v) {
                VertexOutput o = (VertexOutput)0;
                o.uv0 = v.texcoord0;
                o.uv1 = v.texcoord1;
                o.uv2 = v.texcoord2;
                #ifdef LIGHTMAP_ON
                    o.ambientOrLightmapUV.xy = v.texcoord1.xy * unity_LightmapST.xy + unity_LightmapST.zw;
                    o.ambientOrLightmapUV.zw = 0;
                #elif UNITY_SHOULD_SAMPLE_SH
                #endif
                #ifdef DYNAMICLIGHTMAP_ON
                    o.ambientOrLightmapUV.zw = v.texcoord2.xy * unity_DynamicLightmapST.xy + unity_DynamicLightmapST.zw;
                #endif
                o.normalDir = UnityObjectToWorldNormal(v.normal);
                o.tangentDir = normalize( mul( unity_ObjectToWorld, float4( v.tangent.xyz, 0.0 ) ).xyz );
                o.bitangentDir = normalize(cross(o.normalDir, o.tangentDir) * v.tangent.w);
                o.posWorld = mul(unity_ObjectToWorld, v.vertex);
                float3 lightColor = _LightColor0.rgb;
                o.pos = UnityObjectToClipPos( v.vertex );
                TRANSFER_VERTEX_TO_FRAGMENT(o)
                return o;
            }
            float4 frag(VertexOutput i) : COLOR {
                i.normalDir = normalize(i.normalDir);
                float3x3 tangentTransform = float3x3( i.tangentDir, i.bitangentDir, i.normalDir);
                float3 viewDirection = normalize(_WorldSpaceCameraPos.xyz - i.posWorld.xyz);
                float4 _NormalMap_var = tex2D(_NormalMap,TRANSFORM_TEX(i.uv0, _NormalMap));
                float3 normalLocal = _NormalMap_var.rgb;
                float3 normalDirection = normalize(mul( normalLocal, tangentTransform ));
                float3 viewReflectDirection = reflect( -viewDirection, normalDirection );
                float3 lightDirection = normalize(_WorldSpaceLightPos0.xyz);
                float3 lightColor = _LightColor0.rgb;
                float3 halfDirection = normalize(viewDirection+lightDirection);

                UNITY_LIGHT_ATTENUATION(attenuation,i, i.posWorld.xyz);
                float3 attenColor = attenuation * _LightColor0.xyz;
                float Pi = 3.141592654;
                float InvPi = 0.31830988618;

                float node_9886 = 0.0;
                float gloss = node_9886;
                float perceptualRoughness = 1.0 - node_9886;
                float roughness = perceptualRoughness * perceptualRoughness;
                float specPow = exp2( gloss * 10.0 + 1.0 );

                UnityLight light;
                #ifdef LIGHTMAP_OFF
                    light.color = lightColor;
                    light.dir = lightDirection;
                    light.ndotl = LambertTerm (normalDirection, light.dir);
                #else
                    light.color = half3(0.f, 0.f, 0.f);
                    light.ndotl = 0.0f;
                    light.dir = half3(0.f, 0.f, 0.f);
                #endif
                UnityGIInput d;
                d.light = light;
                d.worldPos = i.posWorld.xyz;
                d.worldViewDir = viewDirection;
                d.atten = attenuation;
                #if defined(LIGHTMAP_ON) || defined(DYNAMICLIGHTMAP_ON)
                    d.ambient = 0;
                    d.lightmapUV = i.ambientOrLightmapUV;
                #else
                    d.ambient = i.ambientOrLightmapUV;
                #endif
                #if UNITY_SPECCUBE_BLENDING || UNITY_SPECCUBE_BOX_PROJECTION
                    d.boxMin[0] = unity_SpecCube0_BoxMin;
                    d.boxMin[1] = unity_SpecCube1_BoxMin;
                #endif
                #if UNITY_SPECCUBE_BOX_PROJECTION
                    d.boxMax[0] = unity_SpecCube0_BoxMax;
                    d.boxMax[1] = unity_SpecCube1_BoxMax;
                    d.probePosition[0] = unity_SpecCube0_ProbePosition;
                    d.probePosition[1] = unity_SpecCube1_ProbePosition;
                #endif
                d.probeHDR[0] = unity_SpecCube0_HDR;
                d.probeHDR[1] = unity_SpecCube1_HDR;
                Unity_GlossyEnvironmentData ugls_en_data;
                ugls_en_data.roughness = 1.0 - gloss;
                ugls_en_data.reflUVW = viewReflectDirection;
                UnityGI gi = UnityGlobalIllumination(d, 1, normalDirection, ugls_en_data );
                lightDirection = gi.light.dir;
                lightColor = gi.light.color;

                float NdotL = saturate(dot( normalDirection, lightDirection ));
                float LdotH = saturate(dot(lightDirection, halfDirection));
                float3 specularColor = node_9886;
                float specularMonochrome;
                float4 _MainTexture_var = tex2D(_MainTexture,TRANSFORM_TEX(i.uv0, _MainTexture));
                float3 node_9511 = normalDirection.rgb;
                float node_6886 = normalize(i.posWorld.g);
                float node_9376_if_leA = step(node_6886,0.0);
                float node_9376_if_leB = step(0.0,node_6886);
                float node_1759 = min(0,dot(node_9511.g,node_6886));
                float3 node_6249 = float3(node_9511.r,lerp((node_9376_if_leA*node_1759)+(node_9376_if_leB*max(0,dot(node_9511.g,node_6886))),node_1759,node_9376_if_leA*node_9376_if_leB),node_9511.b);
                float3 node_1351 = (node_6249*node_6249);
                float3 node_3784 = float3(0,0,0);
                float2 node_9531 = float2(i.posWorld.r,i.posWorld.b);
                float4 _SnowTexture_var = tex2D(_SnowTexture,TRANSFORM_TEX(node_9531, _SnowTexture));
                float3 diffuseColor = (_MainTexture_var.rgb+(node_1351.r*node_3784 + node_1351.g*(_SnowTexture_var.rgb*_SnowAmount) + node_1351.b*node_3784)); // Need this for specular when using metallic
                diffuseColor = DiffuseAndSpecularFromMetallic( diffuseColor, specularColor, specularColor, specularMonochrome );
                specularMonochrome = 1.0-specularMonochrome;
                float NdotV = abs(dot( normalDirection, viewDirection ));
                float NdotH = saturate(dot( normalDirection, halfDirection ));
                float VdotH = saturate(dot( viewDirection, halfDirection ));
                float visTerm = SmithJointGGXVisibilityTerm( NdotL, NdotV, roughness );
                float normTerm = GGXTerm(NdotH, roughness);
                float specularPBL = (visTerm*normTerm) * UNITY_PI;
                #ifdef UNITY_COLORSPACE_GAMMA
                    specularPBL = sqrt(max(1e-4h, specularPBL));
                #endif
                specularPBL = max(0, specularPBL * NdotL);
                #if defined(_SPECULARHIGHLIGHTS_OFF)
                    specularPBL = 0.0;
                #endif
                half surfaceReduction;
                #ifdef UNITY_COLORSPACE_GAMMA
                    surfaceReduction = 1.0-0.28*roughness*perceptualRoughness;
                #else
                    surfaceReduction = 1.0/(roughness*roughness + 1.0);
                #endif
                specularPBL *= any(specularColor) ? 1.0 : 0.0;
                float3 directSpecular = attenColor*specularPBL*FresnelTerm(specularColor, LdotH);
                half grazingTerm = saturate( gloss + specularMonochrome );
                float3 indirectSpecular = (gi.indirect.specular);
                indirectSpecular *= FresnelLerp (specularColor, grazingTerm, NdotV);
                indirectSpecular *= surfaceReduction;
                float3 specular = (directSpecular + indirectSpecular);

                NdotL = max(0.0,dot( normalDirection, lightDirection ));
                half fd90 = 0.5 + 2 * LdotH * LdotH * (1-gloss);
                float nlPow5 = Pow5(1-NdotL);
                float nvPow5 = Pow5(1-NdotV);
                float3 directDiffuse = ((1 +(fd90 - 1)*nlPow5) * (1 + (fd90 - 1)*nvPow5) * NdotL) * attenColor;
                float3 indirectDiffuse = float3(0,0,0);
                indirectDiffuse += gi.indirect.diffuse;
                float3 diffuse = (directDiffuse + indirectDiffuse) * diffuseColor;

                float3 finalColor = diffuse + specular;
                return fixed4(finalColor,1);
            }
            ENDCG
        }
        Pass {
            Name "FORWARD_DELTA"
            Tags {
                "LightMode"="ForwardAdd"
            }
            Blend One One
            ZTest Always


            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #define SHOULD_SAMPLE_SH ( defined (LIGHTMAP_OFF) && defined(DYNAMICLIGHTMAP_OFF) )
            #define _GLOSSYENV 1
            #include "UnityCG.cginc"
            #include "AutoLight.cginc"
            #include "Lighting.cginc"
            #include "UnityPBSLighting.cginc"
            #include "UnityStandardBRDF.cginc"
            #pragma multi_compile_fwdadd_fullshadows
            #pragma multi_compile LIGHTMAP_OFF LIGHTMAP_ON
            #pragma multi_compile DIRLIGHTMAP_OFF DIRLIGHTMAP_COMBINED DIRLIGHTMAP_SEPARATE
            #pragma multi_compile DYNAMICLIGHTMAP_OFF DYNAMICLIGHTMAP_ON
            #pragma only_renderers d3d9 d3d11 glcore gles
            #pragma target 3.0
            uniform sampler2D _SnowTexture; uniform float4 _SnowTexture_ST;
            uniform float _SnowAmount;
            uniform sampler2D _MainTexture; uniform float4 _MainTexture_ST;
            uniform sampler2D _NormalMap; uniform float4 _NormalMap_ST;
            struct VertexInput {
                float4 vertex : POSITION;
                float3 normal : NORMAL;
                float4 tangent : TANGENT;
                float2 texcoord0 : TEXCOORD0;
                float2 texcoord1 : TEXCOORD1;
                float2 texcoord2 : TEXCOORD2;
            };
            struct VertexOutput {
                float4 pos : SV_POSITION;
                float2 uv0 : TEXCOORD0;
                float2 uv1 : TEXCOORD1;
                float2 uv2 : TEXCOORD2;
                float4 posWorld : TEXCOORD3;
                float3 normalDir : TEXCOORD4;
                float3 tangentDir : TEXCOORD5;
                float3 bitangentDir : TEXCOORD6;
                LIGHTING_COORDS(7,8)
            };
            VertexOutput vert (VertexInput v) {
                VertexOutput o = (VertexOutput)0;
                o.uv0 = v.texcoord0;
                o.uv1 = v.texcoord1;
                o.uv2 = v.texcoord2;
                o.normalDir = UnityObjectToWorldNormal(v.normal);
                o.tangentDir = normalize( mul( unity_ObjectToWorld, float4( v.tangent.xyz, 0.0 ) ).xyz );
                o.bitangentDir = normalize(cross(o.normalDir, o.tangentDir) * v.tangent.w);
                o.posWorld = mul(unity_ObjectToWorld, v.vertex);
                float3 lightColor = _LightColor0.rgb;
                o.pos = UnityObjectToClipPos( v.vertex );
                TRANSFER_VERTEX_TO_FRAGMENT(o)
                return o;
            }
            float4 frag(VertexOutput i) : COLOR {
                i.normalDir = normalize(i.normalDir);
                float3x3 tangentTransform = float3x3( i.tangentDir, i.bitangentDir, i.normalDir);
                float3 viewDirection = normalize(_WorldSpaceCameraPos.xyz - i.posWorld.xyz);
                float4 _NormalMap_var = tex2D(_NormalMap,TRANSFORM_TEX(i.uv0, _NormalMap));
                float3 normalLocal = _NormalMap_var.rgb;
                float3 normalDirection = normalize(mul( normalLocal, tangentTransform ));
                float3 lightDirection = normalize(lerp(_WorldSpaceLightPos0.xyz, _WorldSpaceLightPos0.xyz - i.posWorld.xyz,_WorldSpaceLightPos0.w));
                float3 lightColor = _LightColor0.rgb;
                float3 halfDirection = normalize(viewDirection+lightDirection);

                UNITY_LIGHT_ATTENUATION(attenuation,i, i.posWorld.xyz);
                float3 attenColor = attenuation * _LightColor0.xyz;
                float Pi = 3.141592654;
                float InvPi = 0.31830988618;

                float node_9886 = 0.0;
                float gloss = node_9886;
                float perceptualRoughness = 1.0 - node_9886;
                float roughness = perceptualRoughness * perceptualRoughness;
                float specPow = exp2( gloss * 10.0 + 1.0 );

                float NdotL = saturate(dot( normalDirection, lightDirection ));
                float LdotH = saturate(dot(lightDirection, halfDirection));
                float3 specularColor = node_9886;
                float specularMonochrome;
                float4 _MainTexture_var = tex2D(_MainTexture,TRANSFORM_TEX(i.uv0, _MainTexture));
                float3 node_9511 = normalDirection.rgb;
                float node_6886 = normalize(i.posWorld.g);
                float node_9376_if_leA = step(node_6886,0.0);
                float node_9376_if_leB = step(0.0,node_6886);
                float node_1759 = min(0,dot(node_9511.g,node_6886));
                float3 node_6249 = float3(node_9511.r,lerp((node_9376_if_leA*node_1759)+(node_9376_if_leB*max(0,dot(node_9511.g,node_6886))),node_1759,node_9376_if_leA*node_9376_if_leB),node_9511.b);
                float3 node_1351 = (node_6249*node_6249);
                float3 node_3784 = float3(0,0,0);
                float2 node_9531 = float2(i.posWorld.r,i.posWorld.b);
                float4 _SnowTexture_var = tex2D(_SnowTexture,TRANSFORM_TEX(node_9531, _SnowTexture));
                float3 diffuseColor = (_MainTexture_var.rgb+(node_1351.r*node_3784 + node_1351.g*(_SnowTexture_var.rgb*_SnowAmount) + node_1351.b*node_3784));
                diffuseColor = DiffuseAndSpecularFromMetallic( diffuseColor, specularColor, specularColor, specularMonochrome );
                specularMonochrome = 1.0-specularMonochrome;
                float NdotV = abs(dot( normalDirection, viewDirection ));
                float NdotH = saturate(dot( normalDirection, halfDirection ));
                float VdotH = saturate(dot( viewDirection, halfDirection ));
                float visTerm = SmithJointGGXVisibilityTerm( NdotL, NdotV, roughness );
                float normTerm = GGXTerm(NdotH, roughness);
                float specularPBL = (visTerm*normTerm) * UNITY_PI;
                #ifdef UNITY_COLORSPACE_GAMMA
                    specularPBL = sqrt(max(1e-4h, specularPBL));
                #endif
                specularPBL = max(0, specularPBL * NdotL);
                #if defined(_SPECULARHIGHLIGHTS_OFF)
                    specularPBL = 0.0;
                #endif
                specularPBL *= any(specularColor) ? 1.0 : 0.0;
                float3 directSpecular = attenColor*specularPBL*FresnelTerm(specularColor, LdotH);
                float3 specular = directSpecular;

                NdotL = max(0.0,dot( normalDirection, lightDirection ));
                half fd90 = 0.5 + 2 * LdotH * LdotH * (1-gloss);
                float nlPow5 = Pow5(1-NdotL);
                float nvPow5 = Pow5(1-NdotV);
                float3 directDiffuse = ((1 +(fd90 - 1)*nlPow5) * (1 + (fd90 - 1)*nvPow5) * NdotL) * attenColor;
                float3 diffuse = directDiffuse * diffuseColor;

                float3 finalColor = diffuse + specular;
                return fixed4(finalColor,0);
            }
            ENDCG
        }
    }
    }