How to modularize shaders in Processing 3.x - glsl

Question

I'd like to use the same noise function throughout various .glsl files without copying and pasting code every time.
What is the processing way to achieve this ?

Answer 1

Afaik, there is no way to do this dynamically in Processing. However, you can separately compile your shaders with glslify, which is a GLSL compile-time include system.
glslify (https://github.com/glslify/glslify) is a bit of overkill, though. Whenever I make an OpenGL / GLSL application, I roll my own system.
Something like this (taken from my Java OpenGL Minecraft clone here):
private static String process(String code){
String[]lines=code.split("\n");
for(int i=0;i<lines.length;i++){
if(lines[i].startsWith("#include : ")){
lines[i]=process(Utils.loadFile("path_to_include_directory/"+lines[i].replace("#include : ","")+".glsl"));
}
}
StringBuilder str= new StringBuilder();
for(String s:lines){
str.append(s).append("\n");
}
return str.toString();
}
This code does a copy-paste on includes. Usage:
///// MAIN FILE
#include : bar_module
float foo(vec3 p){
return bar(p * 5.0);
}
///// path_to_include_directory/bar_module.glsl
float bar(vec3 p) {
/* ... ... */
}
This is a recursive includes mechanism, fairly efficient, at runtime. No static compilation needed!
The only downside is that circular dependencies aren't detected. But you shouldn't be in a situation with circular dependencies anyway :)
DISCLAIMER
I don't actually remember how this stuff works, but I think this is the general idea:
File file=new File("my_shader.vert");
file.setContents(process(file.readContents()));
PShader my_shader=new PShader("my_shader");
NOTE: setContents and readContents don't actually exist, but you get the idea :)
PS
Utils.loadFile returns the contents of the filename passed in as a String.