💡 Rewrite main script with ES6, remove worker usage

This commit is contained in:
Mattéo Delabre 2015-12-16 23:03:50 +01:00
parent b18344a217
commit a0d614e06d
2 changed files with 135 additions and 212 deletions

135
scripts/index.js Normal file
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'use strict';
import { body, create } from './dom';
import { randomNumber, randomColor } from './utils';
const content = body.get('#content');
const plotting = body.get('#plotting');
const ctx = plotting.node.getContext('2d');
const padding = 40; // padding between the canvas edges and the points
let image, width, height;
let lastUpdate = -Infinity;
/**
* Create a fractal of given width, height, based on
* a polygon of given amount of vertices, using the
* chaos game applied with given fraction
*
* @param {number} width Fractal width
* @param {number} height Fractal height
* @param {number} fraction Fraction to use
* @param {Array} colors Color of each vertex
* @return {ImageData} Generated pixel data
*/
const chaos = (width, height, fraction, colors) => {
const cx = Math.floor(width / 2);
const cy = Math.floor(height / 2);
const radius = Math.min(cx, cy);
const count = colors.length;
const vertices = [];
const angleStep = 2 * Math.PI / count;
let initialAngle;
// creating 0-width image data will throw an error
if (width <= 0 || height <= 0) {
return ctx.createImageData(1, 1);
}
const image = ctx.createImageData(width, height);
const data = image.data;
// we will rotate around an inscribed circle to calculate
// the vertices' positions. We adapt the initial angle so
// that usual polygons look better
if (count === 3) {
initialAngle = -Math.PI / 2;
} else if (count === 4) {
initialAngle = Math.PI / 4;
} else {
initialAngle = 0;
}
for (let i = 0; i < count; i += 1) {
let current = angleStep * i + initialAngle;
vertices.push([
Math.floor(Math.cos(current) * radius + cx),
Math.floor(Math.sin(current) * radius + cy)
]);
}
// now we apply the chaos algorithm:
// for any point, the next point is a `fraction` of the
// distance between it and a random vertex
let point = vertices[0];
let iterations = 200000;
let drop = 1000;
while (iterations--) {
const vertexNumber = randomNumber(0, count);
const vertex = vertices[vertexNumber], color = colors[vertexNumber];
point = [
Math.floor((point[0] - vertex[0]) * fraction + vertex[0]),
Math.floor((point[1] - vertex[1]) * fraction + vertex[1])
];
// skip the first 1000 points
if (drop === 0) {
const i = (point[1] * width + point[0]) * 4;
data[i] = color[0];
data[i + 1] = color[1];
data[i + 2] = color[2];
data[i + 3] = 255;
} else {
drop--;
}
}
return image;
};
/**
* Render the scene, recalculating the points
* positions if they need to
*
* @return {null}
*/
const render = () => {
// only recalculate every 16.67 ms
if (+new Date() - lastUpdate > 16.67) {
image = chaos(
width - 2 * padding, height - 2 * padding, 1/2,
[[255, 0, 0], [0, 255, 0], [0, 0, 255]]
);
lastUpdate = +new Date();
}
ctx.clearRect(0, 0, width, height);
ctx.putImageData(
image, padding, padding
);
};
/**
* Resize the canvas to fit the new
* window size and redraw the scene
*
* @return {null}
*/
const resize = () => {
width = content.node.clientWidth;
height = content.node.clientHeight;
plotting.setAttr('width', width);
plotting.setAttr('height', height);
render();
};
window.onresize = resize;
resize();

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/*jslint browser:true, nomen:true, plusplus:true, devel:true */
/*globals $, utils */
(function () {
'use strict';
var jCanvas = $('#canvas'), canvas = jCanvas[0], context = canvas.getContext('2d'),
chaos = new window.Worker('js/chaos.js'), button = $('#pt-gen'), count = $('#pt-num'),
size_input = $('#pt-size'), render = $('#pt-render'), render_link = render.find('a'),
vertices_count = $('#pt-vertices'), factor_top = $('#pt-frac-top'), factor_bottom = $('#pt-frac-bottom'),
form_inputs = $('#parameters form p :input'), padding = 10, verticesColors = [],
zoom = 1, zoom_out = $('#zoom-out'), zoom_in = $('#zoom-in');
// presets
$('.setting').click(function (e) {
var id = parseInt($(this).attr('data-setting-id'), 10);
if ($('#parameters form').prop('disabled')) {
return;
}
switch (id) {
case 1:
vertices_count.val(3);
factor_top.val(1);
factor_bottom.val(2);
break;
case 2:
vertices_count.val(5);
factor_top.val(3);
factor_bottom.val(8);
break;
case 3:
vertices_count.val(6);
factor_top.val(1);
factor_bottom.val(3);
break;
case 4:
vertices_count.val(5);
factor_top.val(1);
factor_bottom.val(3);
break;
}
button.click();
});
// zoom level
function updateZoomLevel() {
jCanvas.css({
width: canvas.width * zoom,
height: canvas.height * zoom
});
}
function setZoomLevel(level) {
zoom = level;
updateZoomLevel();
}
zoom_in.click(function () {
if (zoom < 2) {
setZoomLevel(zoom + 0.1);
}
});
zoom_out.click(function () {
if (zoom > 0.1) {
setZoomLevel(zoom - 0.1);
}
});
// returns the position of the vertices of a regular polygon with n angles
// the width and height parameter specifies the radius of the inscripting circle
function getRegularVertices(width, height, vertices) {
var i = 0, shapeVerts = [], angle, x = width / 2, y = height / 2,
rx = width / 2 - padding, ry = height / 2 - padding,
frac = Math.PI * 2 / vertices;
for (i = 0; i < vertices; i++) {
angle = frac * i + Math.PI / 2;
shapeVerts.push([
Math.cos(angle) * rx + x,
Math.sin(angle) * ry + y
]);
}
return shapeVerts;
}
// updates rendering button which allows to download the image
function updateRender() {
render_link.attr('href', canvas.toDataURL());
}
// draw the vertices of the current polygon - wth the lines
function canvasDrawVertices() {
var width = canvas.width, height = canvas.height,
vertices = getRegularVertices(width, height, parseInt(vertices_count.val(), 10)),
vertices_num = vertices.length, i, vertex,
lastVertex = vertices[vertices_num - 1];
context.clearRect(0, 0, width, height);
// one color per vertex
verticesColors = [];
for (i = 0; i < vertices_num; i++) {
verticesColors.push(utils.getRandomColor());
}
// draw lines
context.beginPath();
context.moveTo(lastVertex[0], height - lastVertex[1]);
for (i = 0; i < vertices_num; i++) {
vertex = vertices[i];
context.lineTo(vertex[0], height - vertex[1]);
}
context.stroke();
// draw vertices
for (i = 0; i < vertices_num; i++) {
vertex = vertices[i];
context.fillStyle = utils.rgbToHex(verticesColors[i]);
context.beginPath();
context.arc(vertex[0], height - vertex[1], 3, 0, Math.PI * 2, true);
context.fill();
}
updateRender();
}
function enableForm(enabled) {
form_inputs.prop('disabled', !enabled);
$('#parameters form').prop('disabled', !enabled);
}
// on generate response from the worker
$(chaos).on('message', function (e) {
var points = e.originalEvent.data, length = points.length, i,
data, pdata, point, index, width = canvas.width,
vertexColor, height = canvas.height,
vertices = parseInt(vertices_count.val(), 10);
if (!Array.isArray(points[0])) {
console.error('Error: ' + points);
return;
}
// about the fastest way to draw points array on a canvas:
// http://jsperf.com/filling-a-bunch-of-points-in-canvas
data = context.getImageData(0, 0, width, height);
for (i = 0; i < length; i++) {
point = points[i];
pdata = point[0];
vertexColor = verticesColors[point[1]];
index = (parseInt(pdata[0], 10) + (height - parseInt(pdata[1], 10)) * width) * 4;
data.data[index] = vertexColor[0];
data.data[index + 1] = vertexColor[1];
data.data[index + 2] = vertexColor[2];
data.data[index + 3] = 255;
}
context.putImageData(data, 0, 0);
enableForm(true);
updateRender();
});
// set input size
size_input.change(function () {
var size = parseInt($(this).val(), 10);
canvas.width = size + 2 * padding;
canvas.height = size + 2 * padding;
canvasDrawVertices();
updateZoomLevel();
});
// generate
button.click(function (e) {
var width = canvas.width, height = canvas.height, shape,
vertices = parseInt(vertices_count.val(), 10),
frac = parseInt(factor_top.val(), 10) / parseInt(factor_bottom.val(), 10);
// reset environment
enableForm(false);
canvasDrawVertices();
// regular polygon
shape = getRegularVertices(width, height, vertices);
chaos.postMessage([
parseInt(count.val(), 10) * width,
[width, height],
shape,
frac
]);
e.preventDefault();
});
vertices_count.change(canvasDrawVertices);
canvasDrawVertices();
}());