Shader 之 顶点变形

可以使3D物体通过顶点变形弯曲，常见于跑酷游戏的跑道。可向左、右、上、下弯曲。

Shader "Custom/VertexColorCurved" {
    Properties {
        // Shader需要的6个参数
        _MainTex ("Base (RGB)", 2D) = "white" {}
        _QOffset ("Offset", Vector) = (,,,)
        _Dist ("Distance", Float) = 100.0

        _BrightnessAmount ("Brightness Amount", Float) = 1.0
        _SaturationAmount ("Saturation Amount", Float) = 1.0
        _ContrastAmount ("Contrast Amount", Float) = 1.0
    }

    SubShader {
        Tags { "Queue" = "Transparent"}
        Pass
        {

            Blend SrcAlpha OneMinusSrcAlpha
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            sampler2D _MainTex;

            float4 _QOffset;
            float _Dist;

            fixed _BrightnessAmount;
            fixed _SaturationAmount;
            fixed _ContrastAmount;
            float _OpacityAmount;

            struct v2f {
                float4 pos : SV_POSITION;
                float4 uv : TEXCOORD0;
                float3 viewDir : TEXCOORD1;
                fixed4 color : COLOR;
            };

            v2f vert (appdata_full v)
            {
                   v2f o;

                   float4 vPos = mul (UNITY_MATRIX_MV, v.vertex);
                float zOff = vPos.z/_Dist;
                   vPos += _QOffset*zOff*zOff;
                   o.pos = mul (UNITY_MATRIX_P, vPos);
                   o.uv = v.texcoord;

　　　　　　　　　　　//o.color.rgb = v.color.rgb;  // 取顶点色

                   return o;
            }

            float3 ContrastSaturationBrightness (float3 color, float brt, float sat, float con) {
                // Increase or decrease these values to
                // adjust r, g and b color channels separately
                float avgLumR = 0.5;
                float avgLumG = 0.5;
                float avgLumB = 0.5;  

                // Luminance coefficients for getting luminance from the image
                float3 LuminanceCoeff = float3 (0.2125, 0.7154, 0.0721);  

                // Operation for brightmess
                float3 avgLumin = float3 (avgLumR, avgLumG, avgLumB);
                float3 brtColor = color * brt;
                float intensityf = dot (brtColor, LuminanceCoeff);
                float3 intensity = float3 (intensityf, intensityf, intensityf);  

                // Operation for saturation
                float3 satColor = lerp (intensity, brtColor, sat);  

                // Operation for contrast
                float3 conColor = lerp (avgLumin, satColor, con);  

                return conColor;
            }  

            half4 frag (v2f i) : COLOR0
            {
                fixed4 renderTex = tex2D(_MainTex, i.uv);  

//                  // Apply vertex color
//                  renderTex.rgb *= i.color.rgb;  // 顶点色和贴图混合

                // Apply the brightness, saturation, contrast operations
                renderTex.rgb = ContrastSaturationBrightness (renderTex.rgb, _BrightnessAmount, _SaturationAmount, _ContrastAmount);

                return renderTex;
            }

            ENDCG
        }
    }

    FallBack "Diffuse"
}