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
http://codeflow.org/entries/2012/aug/05/webgl-rendering-of-solid-trails/#source

i’m having trouble understanding few things and if someone can help me it would be great.
here is the project: https://playcanvas.com/project/593722/overview/shader-trail

I can’t understand how to set up the attributes which are used in the vertex shader
these
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

can anyone help please?