JS-Examples/balls.html at master · Marcos-C7/JS-Examples · GitHub

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
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
<!DOCTYPE html>

<html>
<!-- The header -->
<head>
	<title>C7 JavaScript</title>
	<style> body{margin:0px; padding:0px;} </style>
</head>

<!-- The body -->
<body style="background-color:#232b17;">
	<!-- The title bar -->
	<div style="background-color:#a6cb45;width:100%;">
		<h1 style="text-align:center; color:#394625; padding:5px; margin:0; font-family:serif;">Drag and THROW the balls!</h1>
	</div><br />

	<!-- An "invisivle" left bar -->
	<div style="background-color:#232b17;height:300px;width:15%;float:left"></div>

	<!-- The central rectangle -->
	<div style="background-color:#fefcd7;width:70%;float:left">
		<br /><br /><br />
		<!-- This table contains a table and the box color -->
		<table align="center">
			<tr>
				<td colspan="4">
					<canvas id="canvas01" width="850" height="400" style="border:1px solid black;"></canvas>
				</td>
			</tr>
			<tr>
				<td style="text-align:right;">
					<button id="addB" type="button" style="width:120px; height:30px; font-size:1.0em; font-family:serif;">Add ball</button>
				</td>
				<td style="text-align:center;">
					<button id="removeB" type="button" style="width:120px; height:30px; font-size:1.0em; font-family:serif;">Remove ball</button>
				</td>
				<td style="text-align:left;">
					Radius of new ball: <input id="numberT" type="text" size="5" value="30">
				</td>
				<td style="text-align:right;">
					<button id="clearB" type="button" style="width:100px; height:30px; font-size:1.0em; font-family:serif;">Clear</button>
				</td>
			</tr>
		</table>
		<br /><br /><br />
	</div>


	<script>
		//INTIALIZATION CODE
		var	board = new Board("canvas01", "#fefcd7", 140);
		var	draggingBall = false;
		var	mousePos = new Point(0, 0);
		var	oldMousePos = new Point(0, 0);
		var	currentMousePos = new Point(0, 0);
		var	oldDragPos = new Point(0, 0);
		var	mouseScanTime = 0.09;

		//Event listener.
		document.getElementById("addB").addEventListener("click", function(){board.addBall(parseInt(document.getElementById("numberT").value))}, false);
		document.getElementById("removeB").addEventListener("click", function(){board.removeBall()}, false);
		document.getElementById("clearB").addEventListener("click", function(){board.clear()}, false);
		document.getElementById("canvas01").addEventListener("mousedown", canvas01Down, false);
		document.getElementById("canvas01").addEventListener("mousemove", canvas01Move, false);
		document.getElementById("canvas01").addEventListener("mouseup", canvas01Up, false);
		document.addEventListener('mousemove', function(e){mousePos.x = e.clientX || e.pageX; mousePos.y = e.clientY || e.pageY;}, false);

		setInterval(function(){board.updateBoard();}, 1000 / board.fps);
		setInterval(checkMousePos, 1000 * mouseScanTime);

		//OBJECTS
		function	Point(x, y)
		{
			this.x = (x === undefined ? 0 : x);
			this.y = (y === undefined ? 0 : y);

			this.add = function(P) {return new Point(this.x + P.x, this.y + P.y);}
			this.subs = function(P) {return new Point(this.x - P.x, this.y - P.y);}
			this.dotProduct = function(P) {return this.x * P.x + this.y * P.y;}
			this.distance = function(P) {return Math.sqrt((this.x - P.x)*(this.x - P.x) + (this.y - P.y)*(this.y - P.y));}
			this.scale = function(c) {return new Point(c * this.x, c * this.y);}
			this.magnitud = function() {return Math.sqrt(this.x * this.x + this.y * this.y);}
			this.sqrMagnitud = function() {return this.x * this.x + this.y * this.y;}
			this.normalized = function() {return this.scale(1/this.magnitud());}


			//Reflexes this vector with respect to vector z.
			this.reflex = function(z)
			{
				var refl = z.scale(2.0 * z.dotProduct(this) / z.dotProduct(z));
				refl.x -= this.x;
				refl.y -= this.y;
				refl = refl.normalized();
				refl = refl.scale(this.magnitud());
				return refl;
			}
		}

		function	Ball(pos, radius, color, speed)
		{
			this.pos = (pos === undefined ? new Point(0, 0) : new Point(pos.x, pos.y));
			this.radius = (radius === undefined ? 0 : radius);
			this.color = (color === undefined ? "#000000" : color)
			this.speed = (speed === undefined ? new Point(0, 0) : new Point(speed.x, speed.y));
			this.mass = this.radius / 2;
			this.prev_pos = (pos === undefined ? new Point(this.pos.x, this.pos.y) : new Point(pos.x, pos.y));
			this.fixed = false;

			this.fix = function() {this.speed.x = 0; this.speed.y = 0; this.fixed = true;}
			this.unfix = function(speed){this.fixed = false; this.speed = (speed == undefined ? new Point(0, 0) : speed);}

			this.updatePosition = function(dt)
			{
				if(this.fixed) return;
				var F = new Point(0, this.mass * 9.8);
				this.speed.x += (dt / this.mass) * F.x;
				this.speed.y += (dt / this.mass) * F.y;
				this.prev_pos.x = this.pos.x;
				this.prev_pos.y = this.pos.y;
				this.pos.x += this.speed.x * dt;
				this.pos.y += this.speed.y * dt;
			}

			this.checkBallsCollision = function(ball)
			{
				var	distanceVect = ball.pos.subs(this.pos);
				if(distanceVect.sqrMagnitud() < (ball.radius + this.radius) * (ball.radius + this.radius)) return true;
				else return false;
			}

			//Returns a 4-D vector, 1st entry for left wall, 2nd for right wall, 3rd for upper wall and 4th for bottom wall.
			this.checkWallsCollision = function(canvas)
			{
				collisions = [0, 0, 0, 0];
				if(this.pos.x - this.radius < 0) collisions[0] = 1;
				else if(this.pos.x + this.radius > canvas.width) collisions[1] = 1;
				else if(this.pos.y - this.radius < 0) collisions[2] = 1;
				else if(this.pos.y + this.radius > canvas.height) collisions[3] = 1;
				return collisions;
			}

			this.handleBallsCollision = function(ball)
			{
				var	dposx = ball.pos.x - this.pos.x, dposy = ball.pos.y - this.pos.y;
				var	dvx = ball.speed.x - this.speed.x; dvy = ball.speed.y - this.speed.y;
				var	dvdr = dposx * dvx + dposy * dvy;
				var	dist = this.radius + ball.radius;
				var	J = 2 * this.mass * ball.mass * dvdr /((this.mass + ball.mass) * dist);
				var	Jx = J * dposx / dist;
				var	Jy = J * dposy / dist;

				var	dist2 = ((this.radius + ball.radius) - this.pos.subs(ball.pos).magnitud()) / 2;
				this.pos = this.pos.add( this.pos.subs(ball.pos).normalized().scale(this.fixed ? 0 : dist2) );
				ball.pos = ball.pos.add( ball.pos.subs(this.pos).normalized().scale(this.fixed ? 2*dist2 : dist2) );


				this.speed.x += Jx / this.mass;
				this.speed.y += Jy / this.mass;
				ball.speed.x -= Jx / this.mass;
				ball.speed.y -= Jy / this.mass;
			}

		}

		function	Board(canvasID, bgColor, fps)
		{
			//Attributes.
			this.canvas = document.getElementById(canvasID);
			this.context = this.canvas.getContext("2d");
			this.balls = [];
			this.backgroundColor = (bgColor === undefined ? "#ffffff" : bgColor);
			this.fps = (fps === undefined ? 50.0 : fps);
			this.dt = 0.05;
			this.fixed = null;

			//Methods.
			this.width = function()		{return this.canvas.width;}
			this.height = function()	{return this.canvas.height;}
			this.numBalls = function()	{return this.balls.length;}

			this.addBall = function(r)
			{
				if(r < 3) r = 3;
				else if(r > Math.min(this.width(), this.height()) / 3) r = Math.min(this.width(), this.height()) / 3;
				this.balls.push(new Ball(	new Point(this.width()/2, r),
											r,
											rgbToHex(getRandomInt(20, 255), getRandomInt(20, 255), 150)
											,new Point(getRandomInt(-100,100), getRandomInt(-50,50))
											));
			}

			this.removeBall = function()
			{
				if(this.numBalls() > 0) {this.balls.pop()};
			}

			this.clear = function()
			{
				while(this.numBalls() > 0) {this.balls.pop();}
			}

			this.drawBalls = function(balls)
			{
				if(balls === undefined || balls === null || balls === 0) balls = this.balls;
				var oldFill = this.context.fillStyle;

				for(var i = 0; i < balls.length; ++i)
				{
					this.context.fillStyle = balls[i].color;
					this.context.beginPath();
					this.context.arc(balls[i].pos.x, balls[i].pos.y, balls[i].radius, 0, 2*Math.PI);
					this.context.fill();
					this.context.closePath();
				}

				this.context.fillStyle = oldFill;
			}

			this.ereaseBoard = function()
			{
				var oldFill = this.context.fillStyle;

				this.context.beginPath();
				this.context.fillStyle = this.backgroundColor;
				this.context.fillRect(0, 0, this.width(), this.height());
				this.context.closePath();

				this.context.fillStyle = oldFill;
			}

			this.updateBoard = function()
			{
				this.updateBalls();
				this.ereaseBoard();
				this.drawBalls();
			}

			this.updateBalls = function()
			{
				var collisions;

				//Update positions of all the balls.
				for(var b = 0; b < this.numBalls(); ++b) this.balls[b].updatePosition(this.dt);

				//Check for collisions with other balls.
				for(var b1 = 0; b1 < this.numBalls(); ++b1)
				for(var b2 = b1 + 1; b2 < this.numBalls(); ++b2)
				{
					if(this.balls[b1].checkBallsCollision(this.balls[b2])) this.balls[b1].handleBallsCollision(this.balls[b2]);
				}

				//Check for wall collisions.
				for(var b = 0; b < this.numBalls(); ++b)
				{
					collisions = this.balls[b].checkWallsCollision(this.canvas);
					for(var w = 0; w < 4; ++w)
					{
						if(collisions[w] != 0)
						{
							if(w == 0)
							{
								this.balls[b].pos.x	= this.balls[b].radius;
								this.balls[b].speed	= this.balls[b].speed.scale(-1).reflex(new Point(1, 0));
							}
							else if(w == 1)
							{
								this.balls[b].pos.x	= this.width() - this.balls[b].radius - 1;
								this.balls[b].speed	= this.balls[b].speed.scale(-1).reflex(new Point(-1, 0));
							}
							else if(w == 2)
							{
								this.balls[b].pos.y	= this.balls[b].radius;
								this.balls[b].speed	= this.balls[b].speed.scale(-1).reflex(new Point(0, 1));
							}
							else if(w == 3)
							{
								this.balls[b].pos.y	= this.height() - this.balls[b].radius;
								this.balls[b].speed	= this.balls[b].speed.scale(-1).reflex(new Point(0, -1));
							}
						}
					}
				}
			}

			this.fix = function(b) {this.balls[b].fix();}
			this.unfix = function(b, speed) {this.balls[b].unfix(speed === undefined ? new Point(0, 0) : speed);}

			this.fixBallInCoords = function(pos)
			{
				var ball;
				for(var b = this.numBalls()-1; b >= 0; --b)
				{
					ball = this.balls[b];
					if(ball.pos.distance(pos) <= ball.radius + 10)
					{
						ball.fix();
						this.fixed = ball;
						draggingBall = true;
						return true;
					}
				}
				return false;
			}

			this.moveFixed = function(dpos)
			{
				this.fixed.pos = this.fixed.pos.add(dpos);
			}

			this.throwFixed = function(speed)
			{
				this.fixed.unfix(speed === undefined ? new Point(0, 0) : speed);
			}

			this.ereaseBoard();
		}

		//AUXILIARY FUNCTIONS
		function rgbToHex(r, g, b)		{	return "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);	}
		function getRandomInt(min, max)	{	return Math.floor(Math.random() * (max - min + 1)) + min;	}
		function getPosition(element)
		{
			var xPosition = 0;
			var yPosition = 0;
			//Get the position of the canvas relative to the client.
			while (element) {
				xPosition += (element.offsetLeft - element.scrollLeft + element.clientLeft);
				yPosition += (element.offsetTop - element.scrollTop + element.clientTop);
				element = element.offsetParent;
			}
			return { x: xPosition, y: yPosition };
		}

		function	checkMousePos()
		{
			oldMousePos.x = currentMousePos.x; oldMousePos.y = currentMousePos.y;
			currentMousePos.x = mousePos.x; currentMousePos.y = mousePos.y;
		}

		//EVENT HANDLERS
		function	canvas01Down(event)
		{
			var canvasPosition = getPosition(event.currentTarget);
			//Get the click position relative to the canvas.
			var	x = event.clientX - canvasPosition.x;
			var	y = event.clientY - canvasPosition.y;

			if(board.fixBallInCoords(new Point(x, y))) oldDragPos = new Point(x, y);
		}

		function	canvas01Move(event)
		{
			if(draggingBall && x != oldDragPos.x && y != oldDragPos.y)
			{
				var canvasPosition = getPosition(event.currentTarget);
				//Get the click position relative to the canvas.
				var	x = event.clientX - canvasPosition.x;
				var	y = event.clientY - canvasPosition.y;

				board.moveFixed((new Point(x, y)).subs(oldDragPos));
				oldDragPos = new Point(x, y);
			}
		}

		function	canvas01Up(event)
		{
			if(draggingBall)
			{
				var canvasPosition = getPosition(event.currentTarget);
				//Get the click position relative to the canvas.
				var	x = event.clientX - canvasPosition.x;
				var	y = event.clientY - canvasPosition.y;

				board.throwFixed(currentMousePos.subs(oldMousePos).scale(1 / (15*mouseScanTime)));
				oldDragPos = new Point(0, 0);
				draggingBall = false;
			}
		}

	</script>
</body>

</html>