Loading效果之二Shader

代碼如下：

Shader "Hidden/Loading_02"
{
    Properties
    {
        _BgColor("BgColor", Color) = (1, 1, 1, 1)
		_MainColor("MainColor", Color) = (1, 1, 1, 1)
		_Radius ("Radius", Range(0, 0.5)) = 0.1
		_CircleRadius("CircleRadius", Range(0, 0.5)) = 0.1
		_AniRange ("AniRange", Range(0, 1)) = 0.1
		_NormalRate ("NormalRate", Range(0, 1)) = 1
		_Breath ("Breath", float) = 1
		_Num ("Num", int) = 1
    }
    SubShader
    {
		Blend SrcAlpha OneMinusSrcAlpha

        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;
            };

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }
			
			fixed4 _BgColor;
			
			fixed4 _MainColor;
			
			fixed _Radius;

			fixed _CircleRadius; 

			fixed _Breath;

			fixed _AniRange;
			
			int _Num;

			fixed _NormalRate; 
			
			fixed drawCircle(fixed radius, fixed2 uv)
			{
				fixed r = sqrt(uv.x * uv.x + uv.y * uv.y);
				return step(r, radius);
			}
			
			fixed getZeroToOneLoop()
			{	
				return fmod(_Time.y * _Breath, 1);
			}

            fixed4 frag (v2f i) : SV_Target
            {
				fixed2 newUv = i.uv - fixed2(0.5, 0.5);

				float angle = 360.0 / _Num;

				fixed curAngle = degrees(atan2(newUv.y, newUv.x)) + 360.0;

				int interval = curAngle / angle;

				fixed intervalAngle = radians((interval + 0.5) * angle);

				fixed2 circleCenter =  _Radius  * fixed2(cos(intervalAngle), sin(intervalAngle));

				fixed2 circleUv = newUv - circleCenter;

				 // 每個區間索引自增
				interval += _Num * (1 - getZeroToOneLoop());

				interval = fmod(interval, _Num);

				int normalNum = _NormalRate * _Num;

				int normalInterval = clamp(normalNum - 1, 0, _Num - 1);

				// 畫小圓
				fixed scale = 1 + step(normalInterval, interval) * _AniRange * (interval - normalInterval);

				fixed c = drawCircle(_CircleRadius * scale, circleUv);

				_BgColor.a = c;

				_MainColor.a = c;

				return step(normalNum - 1, interval) * _MainColor + step(interval, normalNum - 1) * _BgColor;
            }
            ENDCG
        }
    }
}