`Shader "Custom/Draw" {      Properties      {          _Point1("Point1",vector) = (100,100,0,0)          _Point2("Point2",vector) = (200,200,0,0)          _LP1("linePoint1",vector) = (300,100,0,0)          _LP2("linePoint2",vector) = (600,400,0,0)          _LineWidth("LineWidth",range(1,20)) = 2.0             }      SubShader      {          Pass          {              CGPROGRAM              #pragma vertex vert              #pragma fragment frag                            #include "UnityCG.cginc"                 struct appdata              {                  float4 vertex : POSITION;              };                 struct v2f              {                  float4 vertex : SV_POSITION;              };              float4 _Point1;              float4 _Point2;              float4 _LP1;              float4 _LP2;              float _LineWidth;                                    v2f vert (appdata v)              {                  v2f o;  `
`		//5.4.1以上的API才有的代碼                o.vertex = UnityObjectToClipPos(v.vertex);                  return o;              }                             fixed4 frag (v2f i) : SV_Target              {                  //繪制圓形，此處半徑使用了固定值1000和500,當然大家也可以把他們寫成可調的參數                  if( pow((i.vertex.x- _Point1.x ),2) + pow((i.vertex.y- _Point1.y ),2) <1000   )                  {                      return fixed4(0,1,0,1);                  }                  if( pow((i.vertex.x- _Point2.x ),2) + pow((i.vertex.y- _Point2.y ),2) <500   )                  {                      return fixed4(1,0,0,1);                  }                     //繪制直線上兩點                  if( pow((i.vertex.x- _LP1.x ),2) + pow((i.vertex.y- _LP1.y ),2) <100   )                  {                      return fixed4(0,0,1,1);                  }                  if( pow((i.vertex.x- _LP2.x ),2) + pow((i.vertex.y- _LP2.y ),2) <100   )                  {                      return fixed4(0,0,1,1);                  }                     //計算點到直線的距離                  float d = abs((_LP2.y-_LP1.y)*i.vertex.x + (_LP1.x - _LP2.x)*i.vertex.y +_LP2.x*_LP1.y -_LP2.y*_LP1.x )/sqrt(pow(_LP2.y-_LP1.y,2) + pow(_LP1.x-_LP2.x,2));                  //小於或者等於線寬的一半時，屬於直線范圍                  if(d<=_LineWidth/2)                  {                      return fixed4(0.8,0.2,0.5,1);                  }                     //繪制網格直線                  if( (unsigned int)i.vertex.x% (unsigned int)(0.25*_ScreenParams.x)==0 )                  {                      return fixed4(0,0,1,1);                  }                  if( (unsigned int)i.vertex.y% (unsigned int)(0.1*_ScreenParams.x)==0 )                  {                      return fixed4(0,0,1,1);                  }                  //默認返回白色                  return fixed4(1,1,1,1);                 }              ENDCG          }      }  }`