DeltaVR3DModelGeneration/Assets/Scripts/DeltaHoone/Weather_System/Grass/Old/GrassShaderLearn.shader

Shader "Unlit/GrassShaderLearn"
{
    Properties {
        _MainTex ("Texture", 2D) = "white" {}
        _Color ("Color", COlor) = (1,1,1,1)
        _BottomCol ("Bottom", COlor) = (1,1,1,1)
        _TopCol ("Top", COlor) = (1,1,1,1)
        _BendRotationRandom("Bend Rotation Random", Range(0, 1)) = 0.2

        _BladeWidth("Blade Width", Float) = 0.05
        _BladeWidthRandom("Blade Width Random", Float) = 0.02
        _BladeHeight("Blade Height", Float) = 0.5
        _BladeHeightRandom("Blade Height Random", Float) = 0.3

        _TessellationUniform("Tessellation Uniform", Range(1, 64)) = 1
        }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma geometry geo
            //#pragma hull hull
            //#pragma domain domain
            // make fog work
            #pragma multi_compile_fog

            #include "UnityCG.cginc"
            //#include "Shaders/CustomTessellation.cginc"

            struct appdata
            {
                float2 uv : TEXCOORD0;
                float4 vertex : POSITION;
                float3 normal : NORMAL;
                float4 tangent : TANGENT;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                //UNITY_FOG_COORDS(1)
                float4 vertex : SV_POSITION;
                float3 normal : NORMAL;
                float4 tangent : TANGENT;
            };

            struct geometryOutput {
                float4 pos : SV_POSITION;
                float2 uv : TEXCOORD0;
                };

            geometryOutput VertexOutput(float3 pos, float2 uv){
                geometryOutput o;
                o.pos = UnityObjectToClipPos(pos);
                o.uv = uv;
                return o;
                }

            float rand(float3 co){
                return frac(sin(dot(co.xyz, float3(12.9898, 78.233, 53.539))) * 43758.5453);
                }
            float3x3 AngleAxis3x3(float angle, float3 axis){
                float c, s;
                sincos(angle, s, c);
                float t = 1 - c;
                float x = axis.x;
                float y = axis.y;
                float z = axis.z;
                return float3x3(
                    t * x * x + c, t * x * y - s * z, t * x * z + s * y,
                    t * x * y + s * z, t * y * y + c, t * y * z - s * x,
                    t * x * z - s * y, t * y * z + s * x, t * z * z + c
                    );
                }

            sampler2D _MainTex;
            float4 _MainTex_ST;
            fixed4 _Color, _BottomCol, _TopCol;
            float _BendRotationRandom;

            float _BladeHeight;
            float _BladeHeightRandom;   
            float _BladeWidth;
            float _BladeWidthRandom;

            v2f vert (appdata v) {
                v2f o;
                o.vertex = v.vertex;//UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                o.normal = v.normal;
                o.tangent = v.tangent;
                //UNITY_TRANSFER_FOG(o,o.vertex);
                return o;
                }

            [maxvertexcount(3)]
            void geo(triangle v2f IN[3] : SV_POSITION, inout TriangleStream<geometryOutput> triStream) {
                float3 pos = IN[0].vertex;
                float3 vNormal = IN[0].normal;
                float4 vTangent = IN[0].tangent;
                float3 vBinormal = cross (vNormal,vTangent)*vTangent.w;

                float height = (rand(pos.zyx) * 2 - 1) * _BladeHeightRandom + _BladeHeight;
                float width = (rand(pos.xzy) * 2 - 1) * _BladeWidthRandom + _BladeWidth;

                float3x3 tangentToLocal = float3x3(
                    vTangent.x, vBinormal.x, vNormal.x,
                    vTangent.y, vBinormal.y, vNormal.y,
                    vTangent.z, vBinormal.z, vNormal.z
                    );
                float3x3 facingRotationMatrix = AngleAxis3x3(rand(pos) * UNITY_TWO_PI, float3(0, 0, 1));
                float3x3 bendRotationMatrix = AngleAxis3x3(rand(pos.zzx) * _BendRotationRandom * UNITY_PI * 0.5, float3(-1, 0, 0));
                float3x3 transformationMatrix = mul(mul(tangentToLocal, facingRotationMatrix),bendRotationMatrix);

                triStream.Append(VertexOutput(pos + mul(transformationMatrix, float3(width, 0, 0 )), float2(0  ,0) ));
                triStream.Append(VertexOutput(pos + mul(transformationMatrix, float3(-width, 0, 0)), float2(1  ,0) ));
                triStream.Append(VertexOutput(pos + mul(transformationMatrix, float3(height, 0, 1   )), float2(0.5,1) ));


                }

            fixed4 frag (geometryOutput i) : SV_Target {
                // sample the texture
                fixed4 col = tex2D(_MainTex, i.uv) * _Color;
                // apply fog
                //UNITY_APPLY_FOG(i.fogCoord, col);
                return lerp(_BottomCol, _TopCol, i.uv.y) * _Color;
                }
            ENDCG
        }
    }
}