-
Notifications
You must be signed in to change notification settings - Fork 0
/
first_canvas.html
223 lines (190 loc) · 5.27 KB
/
first_canvas.html
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
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
<html>
<head>
text
<script>
// Constants
const GAME_WIDTH = 600;
const GAME_HEIGHT = 400;
const KEY_UP = 38;
const KEY_DOWN = 40;
const PADDLE_WIDTH = 10;
const PADDLE_HEIGHT = 50;
const BACKGROUND_COLOUR = "#000000";
const PLAYER_COLOUR = "#FFFFFF";
const COMPUTER_COLOUR = "#FF0000"
const BALL_COLOUR = "#FFFFFF";
// Get the middle y-value to draw the paddle using the relationship between
// the height of the canvas and the height of the paddle
const MIDDLE_Y = (GAME_HEIGHT-PADDLE_HEIGHT)/2
/* Entities in the game */
var player = new Player();
var computer = new Computer();
var ball = new Ball(GAME_WIDTH/2, GAME_HEIGHT/2);
/* PADDLE */
function Paddle(x, y, width, height) {
this.x = x;
this.y = y;
this.width = width;
this.height = height;
this.x_speed = 0;
this.y_speed = 0;
}
Paddle.prototype.render = function(colour) {
context.fillStyle = colour;
context.fillRect(this.x, this.y, this.width, this.height);
}
Paddle.prototype.move = function(x, y) {
this.x += x;
this.y += y;
this.x_speed = x;
this.y_speed = y;
if (this.y < 0) {
// all the way to the bottom
this.y = 0;
this.y_speed = 0;
} else if (this.y + this.height > GAME_HEIGHT) {
// all the way to the top
this.y = GAME_HEIGHT - this.height;
this.y_speed = 0;
}
}
/* BALL */
function Ball(x, y) {
this.x = x;
this.y = y;
this.x_speed = 3;
this.y_speed = 0;
this.radius = 5;
}
Ball.prototype.render = function(colour) {
context.beginPath();
context.arc(this.x, this.y, this.radius, 2 * Math.PI, false);
context.fillStyle = colour;
context.fill();
}
Ball.prototype.update = function(paddle1, paddle2) {
this.x += this.x_speed;
this.y += this.y_speed;
var top_x = this.x - 5;
var top_y = this.y - 5;
var bottom_x = this.x + 5;
var bottom_y = this.y + 5;
if (this.y - 5 < 0) { // hitting the top wall
this.y = 5;
this.y_speed = -this.y_speed;
} else if (this.y + 5 > GAME_HEIGHT) { // hitting the bottom wall
this.y = GAME_HEIGHT-5;
this.y_speed = -this.y_speed;
}
// A point was score, reset the ball
if (this.x < 0 || this.x > GAME_WIDTH) {
this.x_speed = 3;
this.y_speed = 0;
this.x = GAME_WIDTH/2;
this.y = GAME_HEIGHT/2;
paddle1.y = MIDDLE_Y;
paddle2.y = MIDDLE_Y;
}
if (top_x < 300) {
if (top_y < (paddle1.y + paddle1.height) && bottom_y > paddle1.y
&& top_x < (paddle1.x + paddle1.width) && bottom_x > paddle1.x) {
// hit the player's paddle
this.x_speed = 3;
this.y_speed += (paddle1.y_speed / 2);
this.x += this.x_speed;
}
} else {
if (top_y < (paddle2.y + paddle2.height) && bottom_y > paddle2.y
&& top_x < (paddle2.x + paddle2.width) && bottom_x > paddle2.x) {
// hit the computer's paddle
this.x_speed = -3;
this.y_speed += (paddle2.y_speed / 2);
this.x += this.x_speed;
}
}
};
/* PLAYER */
function Player() {
this.paddle = new Paddle(10, MIDDLE_Y, PADDLE_WIDTH, PADDLE_HEIGHT);
}
Player.prototype.update = function() {
for (var key in keysDown) {
var value = Number(key);
if (value == KEY_UP) {
this.paddle.move(0, -4);
} else if (value == KEY_DOWN) {
this.paddle.move(0, 4);
} else {
this.paddle.move(0, 0);
}
}
}
Player.prototype.render = function(colour) {
this.paddle.render(colour);
}
/* COMPUTER */
function Computer() {
this.paddle = new Paddle(GAME_WIDTH-20, MIDDLE_Y, PADDLE_WIDTH, PADDLE_HEIGHT);
}
Computer.prototype.update = function(ball) {
var y_pos = ball.y;
var diff = -( (this.paddle.y + (this.paddle.height / 2) ) - y_pos);
if (diff < 0 && diff < -4) { // max speed left
diff = -4;
} else if (diff > 0 && diff > 4) { // max speed right
diff = 4;
}
this.paddle.move(0, diff);
if (this.paddle.y < 0) {
this.paddle.y = 0;
} else if (this.paddle.y + this.paddle.height > 400) {
this.paddle.y = 400 - this.paddle.height;
}
}
Computer.prototype.render = function(colour) {
this.paddle.render(colour);
}
// Tell the browser we wish to perform animation
var animate = window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
function(callback) { window.setTimeout(callback, 1000/60) };
// Set up a 2D canvas
var canvas = document.createElement('canvas');
canvas.width = GAME_WIDTH;
canvas.height = GAME_HEIGHT;
var context = canvas.getContext('2d');
// When the page loads, attach the canvas to the screen
window.onload = function() {
document.body.appendChild(canvas);
animate(step);
};
var step = function() {
update(); // Update all our objects
render(); // Render those objects
animate(step); // Use requestAnimationFrame to call step()
};
var update = function() {
player.update();
computer.update(ball);
ball.update(player.paddle, computer.paddle);
};
var render = function() {
context.fillStyle = BACKGROUND_COLOUR;
context.fillRect(0, 0, GAME_WIDTH, GAME_HEIGHT);
player.render(PLAYER_COLOUR);
computer.render(COMPUTER_COLOUR);
ball.render(BALL_COLOUR);
}
/* CONTROLS */
var keysDown = {}; // Keep track of which key is pressed
window.addEventListener("keydown", function(event) {
keysDown[event.keyCode] = true;
});
window.addEventListener("keyup", function(event) {
delete keysDown[event.keyCode];
})
</script>
</head>
<body></body>
</html>