实现效果：

实现代码：

Shader "Custom/LineSDF"
{Properties{}SubShader{Tags { "RenderType"="Opaque" }Pass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"struct appdata{float4 vertex : POSITION;fixed2 uv:TEXCOORD0;};struct v2f{float4 vertex : SV_POSITION;fixed2 uv:TEXCOORD0;};float line_segment(float2 p, float2 a, float2 b) {float2 ba = b - a;float2 pa = p - a;float h = clamp(dot(pa, ba) / dot(ba, ba), 0., 1.);return length(pa - h * ba);} float3 mix(float3 e1, float3 e2, float e3){return e1 * (1-e3) + e2 * e3; }v2f vert (appdata v){v2f o;o.vertex = UnityObjectToClipPos(v.vertex);o.uv = v.uv;return o;}float4 frag (v2f i) : SV_Target{float2 pos = (i.uv - 1 * .5) / 1;float zoom = 2.5;pos *= zoom;float2 v1 = cos(_Time.x + float2(0.,5.));float2 v2 = cos(_Time.x + float2(0.,5.) + 3.1);float thickness = .2 * (.5 + .5 * sin(_Time.x * 1.));float d = line_segment(pos, v1, v2) - thickness;float3 color = float3(1,1,1) - sign(d) * float3(0,0,0);color *= 1.5 - exp(.5 * abs(d));color *= .5 + .3 * cos(120. * d);color = mix(color, float3(1,1,1), 1. - smoothstep(.0, .015, abs(d)));return float4(color, 1.);}ENDCG}}
}

注：在ShaderToy里的fragCoord就相当于顶点着色器传过来的uv值。 

参考链接：

Line Segment (SDF) (shadertoy.com)

Inigo Quilez :: computer graphics, mathematics, shaders, fractals, demoscene and more (iquilezles.org)