Quick start: understanding Emp

Introduction

Emp is a single program that always receives two inputs: a model file and a script file. The former is meant to provide a basis of geometry, materials, location, weather and other things; while the latter is meant to perform actions and calculatons over this basis.

emp model script.lua [arguments]

An example of this could be

# This line of code will test if
emp - hello

Then Emp should print

hello from Emp!

What you just did was to say Emp to read no input file (thus the dash), and to run the hello.lua file located in the EMPATH. Calling Emp without any input model (i.e. using the emp - script notation) makes it start with an empty model. You can use the script itself to build the model.

The scripts for Emp are written in Lua. This is a programming language designed to be embedded in other programs. So, in addition to all the Lua core functions, Emp adds several functions to interact with the model and perform calculations.

Emp effectively becomes a Lua interpreter, so calling it without a model allows runing Lua scripts. This is what we will do in the Lua for Emp users section