#!/usr/bin/clisp
;;;;
;;;; Terra Nostra is a Minecraft-like survival game for the commandline.
;;;; 
;;;; (c) 2018 Daniel Vedder
;;;;

(defvar *world* NIL)

(defstruct patch
	(pos '(0 0)) ;position
	(alt 0) ;altitude
	(streams-in NIL)
	(streams-out NIL))

(defun init-matrix (size)
	"Create a square matrix of empty patches"
	(do ((y 0 (1+ y)) (world NIL) (row NIL NIL))
		((= y size) world)
		(dotimes (x size)
			(setf row (append row (list (make-patch :pos (list x y))))))
		(setf world (append world (list row)))))

(defun coord (x y &optional (world *world*))
	"Return the patch at the given coordinates or NIL if out of bounds"
	(unless (or (< x 0) (< y 0) (> x (length world)) (> y (length world)))
		(nth x (nth y world))))