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;;;; Copyright (C) 2018 Jakob L. Kreuze, All Rights Reserved.
;;;;
;;;; This file is part of slime-the-world.
;;;;
;;;; slime-the-world 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.
;;;;
;;;; slime-the-world 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 slime-the-world. If not, see <http://www.gnu.org/licenses/>.
(local lume (require :lib.lume))
(local draw (require :draw))
(local gravity 128)
;; Returns a pair, (x, y) that represents the player's next position, assuming
;; that it did /not/ collide with anything. The role of collision detection, and
;; further, setting the player's position, is on the world.
(fn next-position [player dt]
(let [x (+ (. player :x-pos) (* dt (. player :x-vel)))
y (+ (. player :y-pos) (* dt (. player :y-vel)))]
(values x y)))
(fn next-x-vel [player dt]
(let [last-x-vel (. player :x-vel)
moving-right (. player :action :right)
moving-left (. player :action :left)
abs-x-vel (. player :goal-x-vel)
goal-x-vel (if moving-right abs-x-vel moving-left (- abs-x-vel) 0)]
(lume.lerp last-x-vel goal-x-vel dt)))
(fn next-y-vel [player dt]
(let [last-y-vel (. player :y-vel)
jumping (. player :action :jump)
grounded (. player :grounded)
jumping-y-vel (- last-y-vel (. player :goal-y-vel))]
(if (and jumping grounded) jumping-y-vel
grounded 0
:else (+ (. player :y-vel) (* gravity dt)))))
(fn move-right [player]
(tset player :orientation :right)
(tset player :action :right true)
(tset player :action :left false)
(tset player :x-vel (/ (. player :x-vel) 2)))
(fn stop-right [player]
(tset player :action :right false)
(tset player :x-vel (/ (. player :x-vel) 2)))
(fn move-left [player]
(tset player :orientation :left)
(tset player :action :left true)
(tset player :action :right false)
(tset player :x-vel (/ (. player :x-vel) 2)))
(fn stop-left [player]
(tset player :action :left false)
(tset player :x-vel (/ (. player :x-vel) 2)))
(fn jump [player]
(tset player :action :jump true)
(when (> 10 (math.abs (. player :y-vel)))
(tset player :y-vel (- (. player :goal-y-vel)))))
(fn bounce [player x-normal y-normal]
(tset player :x-vel (- (* 8 x-normal) (. player :x-vel)))
(tset player :y-vel (- (math.abs (* 8 y-normal)) (. player :y-vel))))
(local player-sheet
{:img (love.graphics.newImage "art/swanky.png")
:orientation-offset 128
:width 24 :height 22
:padding-x 8 :padding-y 10})
(fn draw-player [player x y]
(let [x-offset (if (= (. player :orientation) :left) 4 0)
x-offset (+ x-offset (. player :animation-x-offset))
y-offset (. player :animation-y-offset)]
(draw.tile x y player-sheet x-offset y-offset)))
(fn next-frame [frame timer]
(if (> 0 timer)
(if (>= (+ 1 frame) 4) 0 (+ 1 frame))
frame))
(fn next-player-animation-x-offset [player]
(let [timer (. player :animation-timer)
frame (. player :animation-x-offset)
jumping (. player :action :jump)
moving (or (. player :action :right) (. player :action :left))
grounded (> 10 (math.abs (. player :y-vel)))
walking (and moving grounded)]
(if jumping (if (> 3 frame) (next-frame frame timer) 3)
walking (next-frame frame timer)
:else 0)))
(fn next-player-animation-y-offset [player]
(let [jumping (. player :action :jump)
moving (or (. player :action :right) (. player :action :left))
grounded (> 10 (math.abs (. player :y-vel)))
walking (and moving grounded)]
(if jumping 2
walking 1
:else 0)))
;; Statefully modifies the animation parameters associated with `player'.
(fn update-player-animations [player dt]
(when (> 10 (math.abs (. player :y-vel)))
(tset player :action :jump false))
(let [timer (. player :animation-timer)]
(tset player :animation-timer (- timer dt)))
(tset player :animation-x-offset (next-player-animation-x-offset player))
(tset player :animation-y-offset (next-player-animation-y-offset player))
(when (> 0 (. player :animation-timer))
(tset player :animation-timer 0.1)))
;; Returns a new player object.
(fn new-player []
{:width (. player-sheet :width)
:height (. player-sheet :height)
:goal-x-vel 128
:goal-y-vel 128
:x-pos 0
:y-pos 0
:x-vel 0
:y-vel 0
:cur-health 5
:max-health 5
:orientation :right
:animation-x-offset 0
:animation-y-offset 0
:animation-timer 0
:grounded false
:action {:jump false
:right false
:left false}
:next-position next-position
:next-x-vel next-x-vel
:next-y-vel next-y-vel
:impact-bottom impact-bottom
:impact-top impact-top
:impact-left impact-left
:impact-right impact-right
:move-right move-right
:stop-right stop-right
:move-left move-left
:stop-left stop-left
:jump jump
:bounce bounce
:draw draw-player
:update update-player-animations})
{:new new-player}
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