Convert Trail Shader To PlayCanvas


hi all,

i’m trying to convert the following trail shader that is written in webgl to be used in playcanvas

i’m having trouble understanding few things and if someone can help me it would be great.
here is the project:

I can’t understand how to set up the attributes which are used in the vertex shader
attribute vec4 last, current, next;
attribute vec3 barycentric;
attribute float texoff;

by he way i’m not drawing a texutre to make it simpler i’m just drawing a color