frpong/src/cljs/frpong/core.cljs

278 lines
12 KiB
Clojure

(ns frpong.core
(:require [frpong.helpers :refer (mult tap diff-chan key-chan frame-chan sustain)]
[cljs.core.async :refer [<! >! chan put! close! sliding-buffer]]
[domina :as dom :refer [log]]
[domina.events :as ev])
(:require-macros [cljs.core.async.macros :as m :refer [go]]
[frpong.core :refer (go-loop)]))
;;
;; Signal Diagram
;;
;; +---------------------+
;; | +-------------+ |
;; | | | |
;; v v | |
;; +----------+ vel-chan | |
;; +-->|c-detector+----------+ |
;; | +----------+ | |
;; | +-----------------+ |
;; | | +-----------------+
;; | | | |
;; | v v |
;; +---------+ frame-chan +------+ tick-chan | +----------+ pos-chan |
;; |frame-gen+------------>|ticker+-----------+-->|positioner+--------------+
;; +---------+ +------+ +----------+ |
;; +---------------------+
;; |
;; v
;; +----------+
;; | renderer |
;; +----------+
(defn rand [] (.random js/Math))
(defn abs [x] (.abs js/Math x))
(def PI 3.141592653589793)
(defn deg->rad [deg] (* (/ deg 180) PI))
(defn cos [x] (.cos js/Math x))
(defn sin [x] (.sin js/Math x))
(defn tick-chan [frames]
(let [c (chan)]
(go
(loop [prev (<! frames)]
(if-let [t (<! frames)]
(do (when (< t (* 10 prev)) (>! c t))
(recur t))
(close! c))))
c))
(defn next-pos [[x y] [vel-x vel-y] tick]
[(+ x (* vel-x tick)) (+ y (* vel-y tick))])
(defn ^:export frpong []
(let [width 800
height 400
padding 5
paddle-size 100
paddle-width 10
ball-radius 5
ball-speed 0.33
init-pos [(/ width 2) (/ height 2)]
init-vel (let [sgn #(if (< % 0.5) -1 1)
deg (+ 35 (* 20 (rand)))
rad (deg->rad deg)]
(map #(* ball-speed %)
[(* (sgn (rand)) (sin rad)) (* (sgn (rand)) (cos rad))]))
paddle-step 20
max-paddle-y (- height paddle-size)
ef-paddle-width (+ paddle-width padding)
init-paddle-pos (/ (- height paddle-size) 2)]
(defn layout-game
"Lays out the game screen."
[]
(doto (dom/by-id "canvas")
(dom/set-style! "width" (str width "px"))
(dom/set-style! "height" (str height "px")))
(doto (dom/by-id "ball")
(dom/set-attr! "r" ball-radius)
(dom/set-attr! "cx" (first init-pos))
(dom/set-attr! "cy" (second init-pos)))
(doseq [id ["lpaddle" "rpaddle"]]
(doto (dom/by-id id)
(dom/set-attr! "width" paddle-width)
(dom/set-attr! "height" paddle-size)
(dom/set-attr! "y" (/ (- height paddle-size) 2))))
(dom/set-attr! (dom/by-id "lpaddle") "x" 0)
(dom/set-attr! (dom/by-id "rpaddle") "x" (- width paddle-width)))
(defn start-game
"Sets up the game by creating the signals and setting up the components and starts the game."
[]
(let [frames (frame-chan) ;; frames signal
pos (chan 1) ;; ball position signal
vel (chan 1) ;; ball velocity signal
pl-pos (chan 1) ;; paddle left position signal
pr-pos (chan 1) ;; paddle right position signal
game-state (chan 1)] ;; game state signal, the state of the game and the current score
(setup-components frames game-state pos vel pl-pos pr-pos)
;; start the game by setting the initial values of the signals
(put! pos init-pos)
(put! vel init-vel)
(put! pl-pos init-paddle-pos)
(put! pr-pos init-paddle-pos)
(put! game-state [:moving 0])))
(defn setup-components
"Multiplexes the signals and sets up the components by connecting them using the signals
tapped from the multiplexers.
The signals are taken as parameters."
[frames game-state pos vel pl-pos pr-pos]
(let [ticks (chan) ;; ticks signal
ticks-m (mult ticks) ;; multiplexers for all signals
pos-m (mult pos)
vel-m (mult vel)
pl-pos-m (mult pl-pos)
pr-pos-m (mult pr-pos)
game-state-m (mult game-state)
;; paddle position signals are not at the same rate as the rest so they need to be
;; sustained at the ticks rate
pl-pos-sust (sustain (tap pl-pos-m) (tap ticks-m (chan (sliding-buffer 1000))))
pr-pos-sust (sustain (tap pr-pos-m) (tap ticks-m (chan (sliding-buffer 1000))))]
;; set up the components
(ticker frames (tap game-state-m) ticks)
(ball-positioner (tap ticks-m) (tap vel-m) (tap pos-m) pos)
(paddle-positioner {83 :down 87 :up} (tap pl-pos-m) pl-pos)
(paddle-positioner {38 :up 40 :down} (tap pr-pos-m) pr-pos)
(collision-detector (tap ticks-m) (tap pos-m) (tap vel-m)
pl-pos-sust pr-pos-sust (tap game-state-m) game-state vel)
(renderer (tap ticks-m) (tap game-state-m) (tap pos-m) (tap vel-m) (tap pl-pos-m) (tap pr-pos-m))))
(defn ticker
"Ticker component.
Converts `frames` signal to ticks and outputs them to the `ticks` signal
as long as the `game-state` signal is not :gameover. Once the `game-state` signal is
:gameover, stops the `frames` signal hence stopping the entire game.
Each tick is the number of milliseconds since the last tick was generated."
[[frames stop-frames] game-state ticks]
(let [ticks-in (tick-chan (diff-chan frames))]
(go (loop []
(let [[state _] (<! game-state)]
(do (>! ticks (<! ticks-in))
(if (= :gameover state)
(stop-frames)
(recur))))))))
(defn ball-positioner
"Ball Positioner component.
Calculates the next ball position using the current ball position (from the `pos-in` signal)
and the current tick (from the `ticks` signal) and outputs it to the `pos-out` signal."
[ticks vel pos-in pos-out]
(go-loop
(let [tick (<! ticks)
pos-next (next-pos (<! pos-in) (<! vel) tick)]
(>! pos-out pos-next))))
(defn paddle-positioner
"Paddle Positioner component.
Captures the keydown signal for the provides keycodes and calculates the next paddle
position using the current paddle position (from the `pos-in` signal) and keydown signal
and outputs it to the `pos-out` signal."
[keycodes pos-in pos-out]
(let [keys (key-chan keycodes)]
(go-loop
(let [pos (<! pos-in)]
(>! pos-out
(condp = (<! keys)
:up (max (- pos paddle-step) 0)
:down (min (+ pos paddle-step) max-paddle-y)))))))
(defn collision-detector [ticks pos vel-in pl-pos pr-pos game-state-in game-state vel-out]
"Collision Detector component.
Detects the collision of the ball with the walls and the paddles and accordingly calculates
and outputs the next ball velocity and next game state to the `vel-out` and `game-state`
signals respectively.
Reads the current tick, ball position, ball velocity and left and right paddle positions from
the `ticks`, `pos`, `vel-in`, `pl-pos` and `pr-pos` signals respectively."
(defn in-y-range? [y paddle-y]
(and (> y (- paddle-y padding)) (< y (+ paddle-y paddle-size padding))))
(defn detect-x-collision [x y lpaddle-y rpaddle-y]
(cond
(< x ef-paddle-width)
(if (in-y-range? y lpaddle-y) :collision-left :gameover)
(> x (- width ef-paddle-width))
(if (in-y-range? y rpaddle-y) :collision-right :gameover)
:else :moving))
(defn detect-y-collision [y]
(cond
(< y padding) :collision-left
(> y (- height padding)) :collision-right
:else :moving))
(defn collision-state? [state]
(or (= state :collision-left) (= state :collision-right)))
(defn adjust-vel [state v]
(condp = state
:collision-left (abs v)
:collision-right (- (abs v))
:moving v
:gameover 0))
(defn perturb [v] (* v (+ 1 (/ (- (rand) 0.5) 25))))
(go-loop
(let [;; get all current values
tick (<! ticks)
[vel-x vel-y] (<! vel-in)
[x y] (<! pos)
lpaddle-y (<! pl-pos)
rpaddle-y (<! pr-pos)
[xn yn] (next-pos [x y] [vel-x vel-y] tick)
[_ score] (<! game-state-in)
;; calculate next position and detect collision
x-state (detect-x-collision xn yn lpaddle-y rpaddle-y)
vel-xn (adjust-vel x-state vel-x)
y-state (detect-y-collision yn)
vel-yn (adjust-vel y-state vel-y)
x-collision (collision-state? x-state)
y-collision (collision-state? y-state)
;; calculate next game state
state-n (cond
(= x-state :gameover) :gameover
(or x-collision y-collision) :collision
:else :moving)
score-n (if x-collision (inc score) score)
;; add a small random perturbation to the ball velocity on collision with paddles
[vel-xn vel-yn] (if x-collision
(map perturb [vel-xn vel-yn])
[vel-xn vel-yn])]
(>! vel-out [vel-xn vel-yn])
(>! game-state [state-n score-n]))))
(defn renderer
"Renderer component.
Renders the ball and paddle positions on the browser. Also shows the game state and stats.
Reads the current values from the signals supplied as parameters."
[ticks game-state pos vel pl-pos pr-pos]
(let [ball-el (dom/by-id "ball")
state-el (dom/by-id "state")
score-el (dom/by-id "score")
lpaddle-el (dom/by-id "lpaddle")
rpaddle-el (dom/by-id "rpaddle")
fps-el (dom/by-id "fps")
vel-el (dom/by-id "vel")]
(go-loop
(let [fps (/ 1000 (<! ticks))
[x y] (<! pos)
[state score] (<! game-state)]
(dom/set-text! fps-el fps)
(dom/set-text! state-el (name state))
(dom/set-text! score-el score)
(dom/set-text! vel-el (<! vel))
(doto ball-el
(dom/set-attr! "cx" x)
(dom/set-attr! "cy" y))))
(go-loop
(dom/set-attr! lpaddle-el "y" (<! pl-pos)))
(go-loop
(dom/set-attr! rpaddle-el "y" (<! pr-pos)))))
;; Everything is ready now. Layout the game and start it on any keypress!
(layout-game)
(ev/listen-once! :keypress start-game)))