shader学习记录——矩形圆形

参考链接

Shader "Unlit/ShapeShader"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            // make fog work
            #pragma multi_compile_fog

            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                UNITY_FOG_COORDS(1)
                float4 vertex : SV_POSITION;
            };

            sampler2D _MainTex;
            float4 _MainTex_ST;

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

            float box0(float2 uv,float left,float right,float top,float bottom)
            {
                if (uv.x>left&&uv.x<right&&uv.y>bottom&&uv.y<top)
                {
                    return 1;
                }
                return 0;
            }
            //距离上下左右边界的距离
            float box1(float2 uv, float left, float right, float top, float bottom)
            {
                float x1 = step(left,uv.x);
                float x2 = step(right, 1-uv.x);
                float y1 = step(top, 1-uv.y);
                float y2 = step(bottom,uv.y);

                float value = x1 * x2 * y1 * y2;
                return value;
            }
            
            float box2(float2 uv, float left, float right, float top, float bottom)
            {
                //左下边界
                float2 bl = step(float2(left,bottom),uv);
                float value = bl.x * bl.y;

                //右上边界
                float2 tr = step(float2(right,top),1-uv);
                value *= tr.x * tr.y;
                return value;
            }

            //绝对值对称法
            float box3(float2 uv, float left, float top)
            {
                float2 b1 = 1 - step(float2(left,top),abs(uv));
                float value = b1.x * b1.y;
                return value;
            }
            //矩形框
            float box4(float2 uv,float left,float top, float width)
            {
                float value = box3(uv,left,top);
                value -= box3(uv,left-width,top-width);
                
                return value;

            }

            //圆形
            float circle(float2 uv,float radius)
            {
                float blur = 0.002;
                float pct = sqrt(uv.x*uv.x+uv.y*uv.y);
                return 1 - smoothstep(radius,radius+blur,pct);
            }
            float circle2(float2 uv,float radius,float width)
            {
                float value = circle(uv,radius);
                value -= circle(uv,radius-width);
                return value;
            }


            fixed4 frag(v2f i) : SV_Target
            {
                 sample the texture
                //fixed4 col = tex2D(_MainTex, i.uv);
                 apply fog
                //UNITY_APPLY_FOG(i.fogCoord, col);
                i.uv -= float2(0.5,0.5);//移动中心点
            float4 col = float4(1,1,0,1);
            float4 box_color = float4(1,0,0,1);

            float value = circle2(i.uv,0.2,0.01);//box4(i.uv,0.3,0.3,0.02);//box2(i.uv,0.2,0.2,0.2,0.2);
            col = lerp(col,box_color, value);

                return col;
            }
            ENDCG
        }
    }
}