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Koroshev Kostya #12

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Koroshev Kostya #12

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ff799bb
New solution
korosidis Jun 20, 2018
d19b533
Fix
korosidis Jun 21, 2018
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126 changes: 20 additions & 106 deletions index.html
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Original file line number Diff line number Diff line change
@@ -1,110 +1,24 @@
<!doctype html>
<html>
<!DOCTYPE html>
<html lang="en">

<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta http-equiv="Cache-Control" content="no-cache"/>

<script>
//пример рисования произвольного множества точек
function example1() {
//получаем html-элемент типа canvas и его характеристики
var canvas = document.getElementById("canvas1");
var canvasHeight = parseInt(canvas.getAttribute("height"));
var canvasWidth = parseInt(canvas.getAttribute("width"));

//создаем 2d context
var context = canvas.getContext('2d');

//создаем "буфер" imageData, в который будем класть новую информацию о цветах
var imageData = context.createImageData(canvasWidth, canvasHeight);
for (var i = 0; i < canvasWidth; i++) {
for (var j = 0; j < canvasHeight; j++) {
var red = 0;
var green = 0;
var blue = (i + j) % 255;
if (i % 20 == 0)
red = 150;
if (j % 20 == 0)
green = 150;
var opacity = 255;

imageData.data[4*(i + canvasWidth*j) + 0] = red;
imageData.data[4*(i + canvasWidth*j) + 1] = green;
imageData.data[4*(i + canvasWidth*j) + 2] = blue;
imageData.data[4*(i + canvasWidth*j) + 3] = opacity;
}
}
//заполненный "буфер" imageData передаем в context для вывода на экран
context.putImageData(imageData, 0, 0);
}

//пример рисования отдельных линий
function example2() {
//получаем html-элемент типа canvas и его характеристики
var canvas = document.getElementById("canvas2");
var canvasHeight = parseInt(canvas.getAttribute("height"));
var canvasWidth = parseInt(canvas.getAttribute("width"));

//создаем 2d context
var context = canvas.getContext('2d');

//задаем стиль линий
context.lineWidth = "5";
context.strokeStyle = "green";

//начинаем создание нового пути
context.beginPath();
//задаем начальную точку линии
context.moveTo(0, 75);
//задаем конечную точку линии и добавляем линию в путь
context.lineTo(150, 100);
//выводим путь на экран
context.stroke();
}

//пример рисования полилиний (сначала вычисляем точки, затем рисуем)
function example3() {
//получаем html-элемент типа canvas и его характеристики
var canvas = document.getElementById("canvas3");
var canvasHeight = parseInt(canvas.getAttribute("height"));
var canvasWidth = parseInt(canvas.getAttribute("width"));

//создаем 2d context
var context = canvas.getContext('2d');

//задаем стиль линий
context.lineWidth = "2";
context.strokeStyle = "#FF0000";

//создаем массив точек
//в качестве точек используются анонимные объекты со свойствами x и y
var points = [{x: 20, y: 50}, {x: 120, y: 50}, {x: 120, y: 100}, {x: 50, y: 20}];

//начинаем создание нового пути
context.beginPath();
//добавляем в путь все точки из массива
for (var i = 0; i < points.length; i++) {
var point = points[i];
if (i == 0)
context.moveTo(point.x, point.y);
else
context.lineTo(point.x, point.y);
}
//выводим путь на экран
context.stroke();
}

//вызывается после загрузки body
function run () {
example1();
example2();
example3();
}
</script>
<meta charset="UTF-8">
<title>Koch Snowflake</title>
</head>

<body onload="run()">
<canvas height='200' width='200' id='canvas1'></canvas>
<canvas height='200' width='200' id='canvas2'></canvas>
<canvas height='200' width='200' id='canvas3'></canvas>
<body>
<label for="recursion">Level of Recursion</label>
<select name="recursion" id="recursion">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
<option value="6">6</option>
<option value="7">7</option>
</select>
<div id="canvas"></div>
<script src="index.js"></script>
</body>

</html>
78 changes: 78 additions & 0 deletions index.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,78 @@
(function() {
var canvas = document.createElement('canvas');
document.getElementById('canvas').appendChild(canvas);

var context = canvas.getContext('2d');
var width = canvas.width = 420;
var height = canvas.height = 420;

var startingPoints = {
p1: {
x: 0,
y: -150
},
p2: {
x: 150,
y: 100
},
p3: {
x: -150,
y: 100
}

};
context.translate(.5 * width, .5 * height);

var koch = function koch(a, b) {
var n = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : 3;
var dx = b.x - a.x,
dy = b.y - a.y;

var dist = Math.sqrt(dx * dx + dy * dy);
var unit = dist / 3;
var angle = Math.atan2(dy, dx);

var p1 = {
x: a.x + dx / 3,
y: a.y + dy / 3
};
var p3 = {
x: b.x - dx / 3,
y: b.y - dy / 3
};
var p2 = {
x: p1.x + Math.cos(angle - Math.PI / 3) * unit,
y: p1.y + Math.sin(angle - Math.PI / 3) * unit
};

if (n > 0) {
koch(a, p1, n - 1);
koch(p1, p2, n - 1);
koch(p2, p3, n - 1);
koch(p3, b, n - 1);
} else {
context.beginPath();
context.moveTo(a.x, a.y);
context.lineTo(p1.x, p1.y);
context.lineTo(p2.x, p2.y);
context.lineTo(p3.x, p3.y);
context.lineTo(b.x, b.y);
context.stroke();
}
};

koch(startingPoints.p1, startingPoints.p2, 5);
koch(startingPoints.p2, startingPoints.p3, 5);
koch(startingPoints.p3, startingPoints.p1, 5);

var input = document.getElementById('recursion');

input.onchange = function() {
var n = input.options[input.selectedIndex].value;
context.clearRect(-width / 2, height / -2, width, height);

koch(startingPoints.p1, startingPoints.p2, n);
koch(startingPoints.p2, startingPoints.p3, n);
koch(startingPoints.p3, startingPoints.p1, n);
};
})();