Hello all -

I'm new to processing, and I'm looking for a good beginner's guide. Specifically, the issues I'm having trouble with are when to call the setup() and draw() functions, and how to return a value from the function.

I've looked through the references, and they're great for a reference, but they don't explain how and when to use something. The examples are great examples, but they don't help me understand how to properly constuct or troubleshoot my own code. I guess what I'm saying is that I'm looking for a significant amount of hand-holding at this point

Here's a specific example of something I'm having problems with: I want to make a function that calculates the length of a line. The example for functions doesn't give an example function that returns a value. I couldn't find 'functions' in the reference. I only happened upon a reference by running into the keyword 'return'. So, I write this:

float lineLength( float x1, float y1, float x2, float y2 ){
 return sqrt( abs(x1-x2)^2 + abs(y1-y2)^2 ) );
}

When I run this in some code, I get 'unexpected token: float'. The project where I'm trying to add this runs otherwise, without my function, so I don't think it's a syntax error elsewhere in the code. I don't really have any idea why I'm getting this error.

You can only use functions, if you use the setup() and draw() mode of programming.

And ^ isn't the power operator.. it's bitwise XOR.

Quote:



Thanks John, that's helpful. Where can I find more information about the setup() and draw() mode?

you can also define objects before setup if you want them to be usable throughout the program.. i.e. if you declare 'int x = 50;" in the setup, then "int x" is only available in setup. Whereas if you declare it before setup it is available in the setup class as well as draw and any other class in the program.

Check out the 'Learning' section of the page and look at how others use the code, lots of useful stuff in there.. and if you are really serious about Processing I'd recommend getting  "Processing: A Programming Handbook for Visual Designers and Artists" by Casey Reas and Ben Fry. It has a lot of useful information in a very readable format.