javascript/canvas4.html at master · nithinmohan/javascript · GitHub

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<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script type="text/javascript"
src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js">
</script>
<script type="text/javascript"> jQuery( function($) {
var ctx = $('#the-canvas')[0].getContext('2d');
var camera = function () {
var camDist, camY;
return {
setFOVandYPos: function (angle, y) {
camY = y;
angle *= (Math.PI / 180);
camDist = (ctx.canvas.width * 0.5) / Math.tan(angle * 0.5);
},
worldToScreen: function (x, y, z) {
return {
sx: (camDist * x) / z,
sy: (camDist * (y - camY)) / z,
scale: (camDist / z)
};
},
screenToWorld: function (sx, sy) {
sx -= ctx.canvas.width / 2;
sy -= ctx.canvas.height / 2;
var wz = (-camY / sy) * camDist;
return {
wx: (sx / camDist * wz).toFixed(3),
wy: (sy / camDist * wz).toFixed(3),
wz: wz.toFixed(3)
};
}
};
}();
var avatar = function (color) {
var that = {},
destX = 0,
destZ = 0,
x = 0,
z = 0,
textX, avatarHW = 40.5,
avatarH = 106,
outlineColor = color.substr(1),
gradient1, gradient2;
outlineColor = (parseInt(outlineColor, 16) & 0xfefefe) >> 1;
outlineColor = '#' + outlineColor.toString(16);
gradient1 = ctx.createRadialGradient(37.7, 55.6, 0.0, 37.7, 55.6, 46.1);
gradient1.addColorStop(0.00, "#fff");
gradient1.addColorStop(1.00, color);
gradient2 = ctx.createRadialGradient(37.6, 15.3, 0.0, 37.6, 15.3, 31.1);
gradient2.addColorStop(0.00, "#fff");
gradient2.addColorStop(1.00, color);
that.remove = false;
that.setDest = function (dstX, dstZ) {
destX = dstX;
destZ = dstZ;
};
that.getZ = function () {
return z;
};
that.getTextX = function () {
return textX;
};
that.move = function (coeff) {
var vx = destX - x,
vz = destZ - z,
dist = Math.sqrt(vx * vx + vz * vz),
p, x1, y1;
// Normalize (make unit length) the vector from old pos to new pos.
if (dist) {
vx /= dist;
vz /= dist;
}
// Apply the vector capped to a maximum of 4 units.
if (dist > 4) {
dist = 4;
}
x += vx * (dist * coeff);
z += vz * (dist * coeff);
p = camera.worldToScreen(x - avatarHW, -avatarH, z);
textX = p.sx + (avatarHW * p.scale) + (ctx.canvas.width / 2);
// Draw the body.
ctx.save();
ctx.translate(p.sx + (ctx.canvas.width / 2), p.sy + (ctx.canvas.height / 2));
ctx.scale(p.scale, p.scale);
ctx.beginPath();
ctx.moveTo(73.1, 83.6);
ctx.bezierCurveTo(71.7, 102.1, 52.2, 105.2, 37.4, 105.2);
ctx.bezierCurveTo(22.5, 105.2, 3.0, 102.1, 1.6, 83.6);
ctx.bezierCurveTo(0.1, 62.7, 14.0, 35.3, 37.4, 35.3);
ctx.bezierCurveTo(60.8, 35.3, 74.7, 62.7, 73.1, 83.6);
ctx.closePath();
ctx.fillStyle = gradient1;
ctx.fill();
ctx.lineWidth = 2.0;
ctx.lineJoin = "miter";
ctx.miterLimit = 4.0;
ctx.strokeStyle = outlineColor;
ctx.stroke();
// Draw the head.
ctx.beginPath();
ctx.moveTo(61.2, 25.3);
ctx.bezierCurveTo(61.2, 38.4, 50.5, 49.1, 37.4, 49.1);
ctx.bezierCurveTo(24.2, 49.1, 13.6, 38.4, 13.6, 25.3);
ctx.bezierCurveTo(13.6, 12.1, 24.2, 1.5, 37.4, 1.5);
ctx.bezierCurveTo(50.5, 1.5, 61.2, 12.1, 61.2, 25.3);
ctx.closePath();
ctx.fillStyle = gradient2;
ctx.fill();
ctx.strokeStyle = outlineColor;
ctx.stroke();
ctx.restore();
};
return that;
};
var textScroller = function () {
var textList = [];
return {
addText: function (text, x, color) {
if (textList.length > 5) {
textList.splice(0, 1);
}
textList.push({
text: text,
x: x,
color: color
});
},
drawText: function () {
var y = (ctx.canvas.height / 2) - 16,
tx, w, x1, y1, w1, i;
ctx.font = "bold 14px sans-serif";
ctx.fillStyle = '#000';
for (i = textList.length - 1; i > −1; i--) {
tx = textList[i];
w = ctx.measureText(tx.text).width / 2;
ctx.beginPath();
y1 = y - 17;
x1 = tx.x - 2; // Same as stroke width.
w1 = w + 16;
// Begin in middle of top.
ctx.moveTo(x1, y1);
// Top and upper-right corner.
ctx.arcTo(x1 + w1, y1, x1 + w1, y1 + 24, 10);
// Right and lower-right corner.
ctx.arcTo(x1 + w1, y1 + 24, x1 - w1 - 10, y1 + 24, 10);
// Bottom and lower-left corner.
ctx.arcTo(x1 - w1, y1 + 24, x1 - w1, y1, 10);
// Left and upper-left corner.
ctx.arcTo(x1 - w1, y1, x1 + w1, y1, 10);
ctx.closePath();
ctx.fillStyle = 'white';
ctx.fill();
ctx.lineWidth = 2;
ctx.strokeStyle = tx.color;
ctx.stroke();
ctx.fillStyle = 'black';
ctx.fillText(tx.text, x1 - w, y);
y -= 28;
}
}
};
}();
var drawBackground = function () {
var linGrad = ctx.createLinearGradient(0, 0, 0, ctx.canvas.height);
linGrad.addColorStop(0, '#00BFFF');
linGrad.addColorStop(0.5, 'white');
linGrad.addColorStop(0.5, '#55dd00');
linGrad.addColorStop(1, 'white');
return function () {
ctx.fillStyle = linGrad;
ctx.fillRect(0, 0, ctx.canvas.width, ctx.canvas.height);
};
}();
var initAndGo = function () {
// Set the field of view and camera vertical position.
camera.setFOVandYPos(125, −128);
// Socket server is running on the local machine
//on port 8999.
var host = "ws://127.0.0.1:8999",
socket, avatarList = [];
// The send function transmits an arbitrary number of arguments to the
// server.
var send = function () {
var data = '';
for (var i = 0; i < arguments.length; i++) {
data += arguments[i] + ',';
}
socket.send(data);
};
try {
socket = new WebSocket(host);
// When the socket connects, it creates a new avatar in a random color.
// It also sets the border color around the text input area.
socket.onopen = function (msg) {
// Random color for avatar.
var rColor = Math.round(0xffffff * Math.random());
rColor = ('#0' + rColor.toString(16)).
replace(/^#0([0-9a-f]{6})$/i, '#$1');
send('CONNECT', rColor, 250);
$('#text-input').css({
border: "2px solid " + rColor,
color: rColor
});
};
socket.onmessage = function (msg) {
if (msg.data) {
var textData = msg.data,
data;
// Parse the returned socket data into a JavaScript object
// via JSON.
textData = textData.replace(/[\x00-\x1f]/, '');
data = $.parseJSON(textData);
for (var userId in data) {
if (avatarList[userId] === undefined) {
// Initialize a new avatar if the the userId doesn't
// yet exist in the avatarList[].
avatarList[userId] = avatar(data[userId].colr);
}
if (data[userId].pos !== undefined) {
// Update avatar's destination x and z positions.
var pos = data[userId].pos.split(',');
avatarList[userId].setDest(pos[0], pos[1]);
}
if (data[userId].chattext !== undefined) {
// Add chat text if present in data.
textScroller.addText(unescape(data[userId].chattext),
avatarList[userId].getTextX(), data[userId].colr);
}
if (data[userId].disconnect) {
// Flag avatar for removal if the server says so.
avatarList[userId].remove = true;
}
}
}
};
} catch (ex) {
alert('Socket error: ' + ex);
}
// Stop text input losing focus when clicking on canvas.
$('#the-canvas').bind('mousedown', this, function (event) {
return false;
});
// Get clicks on canvas and convert to world coordinates.
// Send these coordinates back to the server.
$(ctx.canvas).bind('click', function (evt) {
var canvas, bb, mx, my, p;
canvas = ctx.canvas;
// Get canvas size and position
bb = canvas.getBoundingClientRect();
// Convert mouse event coordinates to canvas coordinates
mx = (evt.clientX - bb.left) * (canvas.width / bb.width);
my = (evt.clientY - bb.top) * (canvas.height / bb.height);
// Stop avatars going too far back.
if (my < canvas.height / 2 + 32) {
return;
}
p = camera.screenToWorld(mx, my);
send('UPDATE', p.wx, p.wz);
});
// Get key presses and send chat text to server if return key is pressed.
// The text is escaped to ensure correct transmission.
$(window).bind('keypress', function (evt) {
if (evt.which == 13) {
send('CHATTEXT', escape($('#text-input').val()));
$('#text-input').val('');
}
});
var oldTime = new Date().getTime();
// The main loop is executed via setInterval at 20-millisecond intervals.
setInterval(function () {
var newTime = new Date().getTime(),
elapsed = newTime - oldTime,
i = 0,
avatarListNew = [],
sortList = [],
// Work out a coefficient of movement based on elapsed time
// to ensure consistent speed across different browsers and hardware.
coeff = elapsed / 20;
oldTime = newTime;
// Draw the background. There is no need to erase
// the canvas first, as the background completely fills it.
drawBackground();
// Place non-removed avatars into sortlist ready for drawing.
// Also place them in avatarListNew.
for (var av in avatarList) {
if (!avatarList[av].remove) {
sortList[i++] = avatarListNew[av] = avatarList[av];
}
}
// Sort the list into z-order.
sortList.sort(function (a, b) {
return b.getZ() - a.getZ();
});
// Move the avatars.
for (i = 0; i < sortList.length; i++) {
sortList[i].move(coeff);
}
// avatarListNew now becomes our current avatar list.
// It does not contain removed avatars.
avatarList = avatarListNew;
// Finally, draw all the chat text.
textScroller.drawText();
}, 20);
}();
</script>
<style type="text/css">
body {font-family: sans-serif}
#text-input {font-size:16px;}
#the-canvas {border:1px solid;}
</style>
</head>
<body>
<canvas id="the-canvas" width='512' height='384'>
</canvas>
<p>
<label for='text-input'>
Chat:
</label>
<input id='text-input' />
</p>
</body>
</html>