shader学习记录——UV旋转缩放平移

参考链接

Shader "Unlit/TransformShader"
{
    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;

          

            float box(float2 uv,float right,float top) {

                float blur = 0.002;//边缘模糊系数

                //通过右上角绘制原点对称的四边形
                float2 bl = 1.0 - smoothstep(float2(right, top) - blur, float2(right, top) + blur, abs(uv.xy));
                float pct = bl.x * bl.y;
                return pct;
            }
            //旋转矩阵
            float3x3 rotate2d(float _angle) {
                float angle = radians(_angle);//角度转为弧度
                return float3x3(cos(angle), -sin(angle), 0.0,
                    sin(angle), cos(angle), 0.0,
                    0.0, 0.0, 1.0
                );
            }
            //缩放矩阵
            float3x3 scale2d(float2 scale) {
                //缩放矩阵作用于坐标系，所以放大和缩小刚好相反，为了使用习惯，缩放参数取倒数
                return float3x3(1.0 / scale.x, 0.0, 0.0,
                    0.0, 1.0 / scale.y, 0.0,
                    0.0, 0.0, 1.0
                );
            }
            //平移矩阵
            float3x3 translation2d(float2 translate) {
                //平移矩阵作用于坐标系，所以平移的方向相反，为了使用习惯，平移参数取负
                return float3x3(1,0,0,
                    0,1,0,
                    translate.x, translate.y, 1
                );
            }

            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;
            }
            fixed4 frag (v2f i) : SV_Target
            {
                 sample the texture
                //fixed4 col = tex2D(_MainTex, i.uv);
                 apply fog
                //UNITY_APPLY_FOG(i.fogCoord, col);
                 float4 col = float4(1,1,0,1);
            float4 box_color = float4(1,0,0,1);

            i.uv -= float2(0.5,0.5);

            i.uv=mul(i.uv,rotate2d(-10*_Time.z));

            i.uv = mul(i.uv, scale2d(float2(_SinTime.y, 1)));

            i.uv = mul(float3(i.uv,1), translation2d(float2(0.3*_SinTime.z, 0)));
            float value = box(i.uv,0.2,0.3);
            col = lerp(col,box_color, value);


                return col;
            }
            ENDCG
        }
    }
}