-
Notifications
You must be signed in to change notification settings - Fork 1
/
index.js
168 lines (133 loc) · 4.73 KB
/
index.js
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
var frameLoop = require('frame-loop')
var collisionChecker = require('./collision-checking')
var FPS_MULTIPLIER = 3 // based on 20fps
var NUM_OF_ROWS = 9
var NUM_OF_COLS = 10
var TILE_SIZE = 32
var BALL = document.getElementById("ball")
// http://stackoverflow.com/questions/5597060/detecting-arrow-key-presses-in-javascript
var LEFT_KEY = 37
var UP_KEY = 38
var RIGHT_KEY = 39
var DOWN_KEY = 40
var OFFSET_X = 14
var OFFSET_Y = 14
var BALL_SPEED_DECAY_ON = 0.99
var BALL_SPEED_DECAY_OFF = 0.9
var BALL_SPEED_THRESH = 0.1
var ballx = 0
var bally = 0
var ballsx = 0
var ballsy = 0
var REGISTER_KEYPRESSES_EVERY_MS = 50
function getTile(row, col) {
// https://developer.mozilla.org/en-US/docs/Web/API/Document/getElementById
return document.getElementById(row + "_" + col)
}
function setTile(row, col, tileNum) {
var numOfZeros = 3 - (tileNum + "").length
var leadingZeros = ""
for (var i = 0; i < numOfZeros; i++) {
leadingZeros += "0"
}
// http://www.w3schools.com/jsref/prop_img_src.asp
getTile(row, col).src = "tiles/tile" + leadingZeros + tileNum + ".gif"
}
function setBallPos(x, y) {
// http://www.w3schools.com/jsref/prop_style_top.asp
// http://stackoverflow.com/questions/2214387/setting-top-and-left-css-attributes
BALL.style.left = ballx = x;
BALL.style.top = bally = y;
}
function initBallPos(row, col) {
setBallPos(col * TILE_SIZE, row * TILE_SIZE);
}
var level = [
[6, 6, 6, 6, 6, 6, 6, 6, 6, 6],
[6, 4, 4, 4, 4, 4, 4, 4, 4, 6],
[6, 4, 6, 6, 6, 6, 6, 4, 6, 6],
[6, 4, 6, 4, 4, 4, 6, 4, 7, 6],
[6, 4, 4, 4, 6, 4, 6, 6, 4, 6],
[6, 6, 6, 6, 6, 4, 4, 6, 4, 6],
[6, 7, 4, 4, 6, 6, 4, 6, 4, 6],
[6, -1, 6, 4, 4, 4, 4, 6, 5, 6],
[6, 6, 6, 6, 6, 6, 6, 6, 6, 6]
];
for(var i = 0; i < NUM_OF_ROWS; i++) {
for(var j = 0; j < NUM_OF_COLS; j++) {
if (level[i][j] == -1) {
initBallPos(i, j)
setTile(i, j, 4)
} else {
setTile(i, j, level[i][j])
}
}
}
/***** Movement *****/
// http://stackoverflow.com/questions/5597060/detecting-arrow-key-presses-in-javascript
// http://stackoverflow.com/questions/5203407/javascript-multiple-keys-pressed-at-once
var keysPressed = {37: 0, 38: 0, 39: 0, 40: 0}
document.onkeydown = function(e) {
e = e || window.event
// dirs = {38: [-1, 0], 40: [1, 0], 37: [0, -1], 39: [0, 1]}
keysPressed[e.keyCode] = 1;
}
document.onkeyup = function(e) {
e = e || window.event
keysPressed[e.keyCode] = 0;
}
function getBallRow() {
return (bally + OFFSET_Y) / TILE_SIZE
}
function getBallCol() {
return (ballx + OFFSET_X) / TILE_SIZE
}
function getBallIX() {
return (ballx + OFFSET_X) % TILE_SIZE * 16 / TILE_SIZE
}
function getBallIY() {
return (bally + OFFSET_Y) % TILE_SIZE * 16 / TILE_SIZE
}
var checkForCollision = collisionChecker(level, [ 6 ])
function updateBallPos(ballSpeedUpdatingTick) {
if (ballSpeedUpdatingTick) {
var extrax = -1 * keysPressed[LEFT_KEY] + keysPressed[RIGHT_KEY]
var extray = -1 * keysPressed[UP_KEY] + keysPressed[DOWN_KEY]
ballsx = (ballsx + extrax) * (extrax ? BALL_SPEED_DECAY_ON : BALL_SPEED_DECAY_OFF)
ballsy = (ballsy + extray) * (extray ? BALL_SPEED_DECAY_ON : BALL_SPEED_DECAY_OFF)
}
if ((ballsx > 0 && getBallIX() > 9 && checkForCollision(getBallRow(), getBallCol() + 1)) ||
(ballsx < 0 && getBallIX() < 5 && checkForCollision(getBallRow(), getBallCol() - 1))) {
ballsx = -ballsx
}
if ((ballsy > 0 && getBallIY() > 9 && checkForCollision(getBallRow() + 1, getBallCol())) ||
(ballsy < 0 && getBallIY() < 5 && checkForCollision(getBallRow() - 1, getBallCol()))) {
ballsy = -ballsy
}
// http://www.w3schools.com/jsref/jsref_abs.asp
if (Math.abs(ballsx) < BALL_SPEED_THRESH) ballsx = 0;
if (Math.abs(ballsy) < BALL_SPEED_THRESH) ballsy = 0;
// console.log(ballsx, ballsy);
setBallPos(ballx + ballsx / FPS_MULTIPLIER, bally + ballsy / FPS_MULTIPLIER)
}
/***** Main Game Loop *****/
function keypressToTickSynchronizer(registerKeypressesEveryMs) {
var elapsedSinceLastTick = 0
return function shouldUpdateMomentumThisTick(elapsedMs) {
var shouldUpdateMomentum = false
elapsedSinceLastTick += elapsedMs
if (elapsedSinceLastTick > registerKeypressesEveryMs) {
elapsedSinceLastTick = elapsedSinceLastTick - registerKeypressesEveryMs
shouldUpdateMomentum = true
}
return shouldUpdateMomentum
}
}
var shouldUpdateMomentumThisTick = keypressToTickSynchronizer(REGISTER_KEYPRESSES_EVERY_MS)
function main(elapsedMsSinceLastTick) {
updateBallPos(shouldUpdateMomentumThisTick(elapsedMsSinceLastTick))
}
var engine = frameLoop({
fps: 20 * FPS_MULTIPLIER
}, main)
engine.run()