flora-search-aurora/engine.lisp
Jaidyn Ann 4d4b65da9c Split off STATE-LOOP into an engine package (⚙)
… while making generic state-function-creators for
both dialogues and overworld maps. This should
make game-specific code more pretty-like!
2023-06-23 13:29:09 -05:00

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Common Lisp
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;;;; Copyright © 2023, Jaidyn Ann <jadedctrl@posteo.at>
;;;;
;;;; This program is free software: you can redistribute it and/or
;;;; modify it under the terms of the GNU General Public License as
;;;; published by the Free Software Foundation, either version 3 of
;;;; the License, or (at your option) any later version.
;;;;
;;;; This program is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;;; GNU General Public License for more details.
;;;;
;;;; You should have received a copy of the GNU General Public License
;;;; along with this program. If not, see <https://www.gnu.org/licenses/>.
;;;; FLORA-SEARCH-AURORA.ENGINE
;;;; The core of the games engine, the loop. Not much to see here other
;;;; than a loop. Honest!
(defpackage :flora-search-aurora.engine
(:nicknames :fsa.eng :engine :)
(:export #:state-loop #:main)
(:use :cl))
(in-package :flora-search-aurora.engine)
(defun state-loop
(states &key (last-matrix (:make-screen-matrix)) (matrix (:make-screen-matrix)) (state-params nil))
"Begin the games loop, which executes (henceforthly called) state-functions over and over again
until Hell freezes over and a new king reigns supreme.
Given a list of state-functions, STATES, it will execute the first function.
Each state-function must take at least a single parameter, a matrix of characters. A state-function
should edit this matrix in-place, replacing its elements with characters that will later be printed
to the terminal.
What the state-function returns is pretty important, having different repercussions:
* NIL — The function is removed from STATES, and so the next function in STATES will start
getting executed instead.
* NIL; List — The function is popped off STATES and the list is used as the new parameters for
the next function in STATES.
* Function — The function is pushed to the front of STATES, and so is executed instead of the
current function.
* List — The current function (front of STATES) continues to be executed with the given
list as a parameters list.
Make note to add a delay w SLEEP to your state functions, or… well, yknow. Your computer will
overheat, or something ¯\_(ツ)_/¯"
(when states
(multiple-value-bind (state-result new-state-params)
(apply (car states) (cons matrix state-params)) ;; Run the latest-added update/draw loop
(:print-screen-matrix (:matrix-delta last-matrix matrix)) ;; Print its results.
(force-output)
(state-loop
(cond ((functionp state-result)
(cons state-result states))
((not state-result)
(cdr states))
('t states))
:last-matrix matrix
:state-params
(cond ((not state-result)
new-state-params)
((listp state-result)
state-result))))))
(defun main (states)
"A toplevel-worthy function that configures rendering and kicks off the
games loop. Lets get started!"
(cl-charms:with-curses ()
(cl-charms:enable-raw-input :interpret-control-characters 't)
(:hide-cursor)
(:clear-screen)
(state-loop states)))