Unity Shader学习（四）试着绘制一个正方形

绘制一个正方形，原理也很简单，判断点是否在尺寸所在范围内即可，先获取到（点坐标-中心坐标）的向量，对x,y两个轴的值与size进行判断。

Shader "Unlit/shader5"
{
    
     
    ///绘制正方形
    Properties
    {
    
    
    _Center("Center",Vector)=(0.5,0.5,0,0)
    _RectColor("RectColor",Color)=(1,1,1,1)
    }
    SubShader
    {
    
    
        Tags {
    
     "RenderType"="Opaque" }
        LOD 100

        Pass
        {
    
    
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag


            #include "UnityCG.cginc"
        struct v2f{
    
    
            float4 vertex:SV_POSITION;
            float4 position:TEXCOORD1;
            float2 uv:TEXCOORD0;
        };
        v2f vert(appdata_base v){
    
    
            v2f o;
            o.vertex=UnityObjectToClipPos(v.vertex);
            o.position=v.vertex;
            o.uv=v.texcoord;
            return o;
        }
        //中心点
        float4 _Center;
        //颜色
        fixed4 _RectColor;
        //绘制正方形
        float rect(float2 pt,float2 size,float2 center){
    
    
            float2 p=pt-center;
            float2 halfsize=size*0.5;
            float hotz=step(-halfsize.x,p.x)-step(halfsize.x,p.x);
            float vert=step(-halfsize.y,p.y)-step(halfsize.y,p.y);
            return hotz*vert;
        }
           

            fixed4 frag (v2f i) : SV_Target
            {
    
    
                float2 pos=i.position.xy;
                float size=0.4;
                float inRect=rect(pos,size,_Center);
                fixed3 col=fixed3(1,1,0)*inRect;
                return fixed4(col,1.0);
            }
            ENDCG
        }
    }
}

绘制长方形也是同样的原理

Shader "Unlit/shader5"
{
    
     
    ///绘制正方形
    Properties
    {
    
    
    _Center("Center",Vector)=(0.5,0.5,0,0)
    _RectColor("RectColor",Color)=(1,1,1,1)
    }
    SubShader
    {
    
    
        Tags {
    
     "RenderType"="Opaque" }
        LOD 100

        Pass
        {
    
    
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag


            #include "UnityCG.cginc"
        struct v2f{
    
    
            float4 vertex:SV_POSITION;
            float4 position:TEXCOORD1;
            float2 uv:TEXCOORD0;
        };
        v2f vert(appdata_base v){
    
    
            v2f o;
            o.vertex=UnityObjectToClipPos(v.vertex);
            o.position=v.vertex;
            o.uv=v.texcoord;
            return o;
        }
        //中心点
        float4 _Center;
        //颜色
        fixed4 _RectColor;
        //绘制正方形
        float rect(float2 pt,float2 size,float2 center){
    
    
            float2 p=pt-center;
            float2 halfsize=size*0.5;
            float hotz=step(-halfsize.x,p.x)-step(halfsize.x,p.x);
            float vert=step(-halfsize.y,p.y)-step(halfsize.y,p.y);
            return hotz*vert;
        }
        float Longrect(float2 pt,float width,float height,float2 center){
    
    
            float2 p=pt-center;
            float2 halfwidth=width*0.5;
            float2 halfheight=height*0.5;
            float hotz=step(-halfwidth.x,p.x)-step(halfwidth.x,p.x);
            float vert=step(-halfheight.y,p.y)-step(halfheight.y,p.y);
            return hotz*vert;
        } 

            fixed4 frag (v2f i) : SV_Target
            {
    
    
                float2 pos=i.position.xy;
                float size=0.4;
                //float inRect=rect(pos,size,_Center);
                float longrect=Longrect(pos,0.4,0.2,_Center);
                fixed3 col=fixed3(1,1,0)*longrect;
                return fixed4(col,1.0);
            }
            ENDCG
        }
    }
}