three.js/src/renderers/shaders/ShaderLib/linedashed_frag.glsl

uniform vec3 diffuse;
uniform float opacity;

uniform float dashSize;
uniform float totalSize;

varying float vLineDistance;

#include <common>
#include <color_pars_fragment>
#include <fog_pars_fragment>
#include <logdepthbuf_pars_fragment>

void main() {

	if ( mod( vLineDistance, totalSize ) > dashSize ) {

		discard;

	}

	vec3 outgoingLight = vec3( 0.0 );
	vec4 diffuseColor = vec4( diffuse, opacity );

	#include <logdepthbuf_fragment>
	#include <color_fragment>

	outgoingLight = diffuseColor.rgb; // simple shader

	#include <fog_fragment>

	gl_FragColor = vec4( outgoingLight, diffuseColor.a );

}