【Unity Shader】用shader控制背景的倾斜渐变

本文转自：http://blog.csdn.net/rickshaozhiheng/article/details/51887255

需要用到一个背景图是斜着渐变的，且需要不断地变化背景颜色，所以不适合美术为每一种颜色背景切图，用shader来控制是最好的

效果图： 

材质Inspector: 

图片效果由三个参数确定，两个颜色分别表示两边的颜色，weights用来计算插值时候的权重

Shader "Custom/Fade"{    Properties    {        [KeywordEnum(X, Y)] _FadeWith ("Fade With", Float) = 0         _Color1 ("Color1", Color) = (1.0,1.0,1.0,1.0)         _Color2 ("Color2", Color) = (0.0,0.0,0.0,1.0)        [PowerSlider(1)] _Weights ("Weights", Range (0.0, 2.0)) = 1.0    }    SubShader    {        Pass        {            CGPROGRAM            #pragma vertex vert            #pragma fragment frag            #include "UnityCG.cginc"            struct appdata            {                float4 vertex : POSITION;                float2 uv : TEXCOORD0;            };            struct v2f            {                float2 uv : TEXCOORD0;                float4 vertex : SV_POSITION;            };            fixed4 _Color1;            fixed4 _Color2;            float _Weights;            //计算给定point点到经过linePoint的直线line的距离            float getPointLineDist(float2 pt, float2 linePoint, float2 ln)            {                float dist;                float2 point2point = pt - linePoint;                dist = length(dot(pt, ln) * ln/length(ln) - point2point);                return dist;            }            v2f vert (appdata v)            {                v2f o;                o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);                o.uv = v.uv;                return o;            }            //注意，uv的最大值是(1, 1)            fixed4 frag (v2f i) : SV_Target            {                fixed4 col;                float2 pt;                      //point                float2 linePoint = float2(1,1);                float2 ln = float2(-1, 1);      //line                pt = float2(i.uv.x, i.uv.y * 1);                float pointLineDist = getPointLineDist(pt, linePoint, ln);                float maxLineDist = getPointLineDist(float2(0, 0), linePoint, ln);                float lp = pointLineDist / maxLineDist * _Weights;                col = lerp(_Color1, _Color2, lp);                return col;            }            ENDCG        }    }}
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扩展：可以再设一个参数来对颜色进行blend，只要乘一下最后return的col就行了。