i need lissajous curves in Canvas. In curves should swim dot.I use this in school, but i can t this do, because i am new in this.
Curves should look like https://www.intmath.com/trigonometric-graphs/svg/svgphp-lissajous-figures-7-s2.svg
Thanks in advance.
function draw_lissajous(omega, sigma, cycles) {
var canvas = $('#scena').get(0);
var ctx = canvas.getContext('2d');
var c_h = 500;
var c_w = 500;
var step = 0.01;
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.strokeStyle = "red";
ctx.beginPath();
for(var i=0; i<(cycles * Math.PI*2) + step; i+=step) {
var x = Math.sin(omega*i + sigma);
var y = Math.sin(i);
var scale=200;
ctx.lineTo(c_w/2 + (x*scale), c_h/2 + (y*scale));
}
ctx.stroke();
}
function update() {
var omega = parseFloat($('input#omega').val());
var sigma = parseFloat($('input#sigma').val());
var cycles = parseFloat($('input#cycles').val());
if (isNaN(omega)) omega = 0;
if (isNaN(sigma)) sigma = 0;
if (isNaN(cycles)) cycles = 10;
draw_lissajous(omega, sigma, cycles);
}
$('input').keyup(function() {
update();
});
update();
<html>
<head>
<title>Lissajous Curves</title>
</head>
<body>
<canvas id='scena' width=500 height=500>
</canvas>
</body>
</html>
Related
<canvas id="myCanvas" width="300" height="300" style="border:1px solid #d3d3d3;">
Mouse over <canvas> does not draw.
var TILE_WIDTH = 30;
var TILE_HEIGHT = 30;
document.getElementById("input").onchange = function() {
var reader = new FileReader();
reader.onload = function(e) {
// get loaded data and render thumbnail.
document.getElementById("image").src = e.target.result;
};
// read the image file as a data URL.
reader.readAsDataURL(this.files[0]);
};
// The first function call to create photomosaic
function photomosaic(image) {
// Dimensions of each tile
var tileWidth = TILE_WIDTH;
var tileHeight = TILE_HEIGHT;
// creating the canvas for photomosaic
var canvas = document.createElement('canvas');
var context = canvas.getContext("2d");
canvas.height = image.height;
canvas.width = image.width;
var imageData = context.getImageData(0, 0, image.width, image.height);
var pixels = imageData.data;
// The Number of mosaic tiles
var numTileRows = image.width / tileWidth;
var numTileCols = image.height / tileHeight;
// The canvas copy of image
var imageCanvas = document.createElement('canvas');
var imageCanvasContext = canvas.getContext('2d');
imageCanvas.height = image.height;
imageCanvas.width = image.width;
imageCanvasContext.drawImage(image, 0, 0);
// A function for finding the average color
function averageColor(row, column) {
var blockSize = 1, // we can set how many pixels to skip
data, width, height,
i = -4,
length,
rgb = {
r: 0,
g: 0,
b: 0
},
count = 0;
try {
data = imageCanvasContext.getImageData(column * TILE_WIDTH, row * TILE_HEIGHT, TILE_HEIGHT, TILE_WIDTH);
} catch (e) {
alert('Not happening this time!');
return rgb;
}
length = data.data.length;
while ((i += blockSize * 4) < length) {
++count;
rgb.r += data.data[i];
rgb.g += data.data[i + 1];
rgb.b += data.data[i + 2];
}
// ~~ used to floor values
rgb.r = ~~(rgb.r / count);
rgb.g = ~~(rgb.g / count);
rgb.b = ~~(rgb.b / count);
return rgb;
}
// Loop through each tile
for (var r = 0; r < numTileRows; r++) {
for (var c = 0; c < numTileCols; c++) {
// Set the pixel values for each tile
var rgb = averageColor(r, c)
var red = rgb.r;
var green = rgb.g;
var blue = rgb.b;
// Loop through each tile pixel
for (var tr = 0; tr < tileHeight; tr++) {
for (var tc = 0; tc < tileWidth; tc++) {
// Calculate the true position of the tile pixel
var trueRow = (r * tileHeight) + tr;
var trueCol = (c * tileWidth) + tc;
// Calculate the position of the current pixel in the array
var pos = (trueRow * (imageData.width * 4)) + (trueCol * 4);
// Assign the colour to each pixel
pixels[pos + 0] = red;
pixels[pos + 1] = green;
pixels[pos + 2] = blue;
pixels[pos + 3] = 255;
};
};
};
};
// Draw image data to the canvas
context.putImageData(imageData, 0, 0);
return canvas;
}
function create() {
var image = document.getElementById('image');
var canvas = photomosaic(image);
document.getElementById("output").appendChild(canvas);
};
#output,
.container {
text-align: center;
}
.inputDiv {
margin: 20px 0px;
}
#image {
width: 300px;
}
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>test</title>
</head>
<body>
<div class="container">
<img id="image" src="https://via.placeholder.com/100" />
<div class="inputDiv">
<input id="input" type="file" accept="image/*">
<button onclick="create()">create</button>
</div>
<canvas id="myCanvas" width="300" height="300" style="border:1px solid #d3d3d3;">
</canvas>
<div id='output'></div>
</div>
</body>
</html>
How do I create a circle when I touch the mouse? I'm sorry for the poor translation. This is the only place to ask. I'm also sorry that the code is very long. Not applicable to script ...
I have to create a rotation wheel with 12 fields like in the image below link :http://www.resilienciacomunitaria.org/
How i create through which approach?
I used canvas for this but not successful i used d3.js svg but not successful .
<!DOCTYPE html>
<html>
<body>
<canvas id="canvas" width="600" height="600"
style="background-color:#ffff">
</canvas>
<script type="text/javascript">
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var radius = canvas.height /2; //400
//alert(radius);
//draw a circle again and agian
ctx.translate(radius, radius);
radius =radius*0.85;
setInterval(drawCircle, 50);
function drawCircle() {
var pos = .01;
var length = 100;
var width = 40;
drawFace(ctx, radius);
drawHand(ctx, pos, length, width);
}
function drawFace(ctx,radius){
ctx.beginPath();
ctx.arc(0, 0, 50, 0, 2 * Math.PI, false);
ctx.fillStyle = '#ffff';
ctx.strokeStyle = 'blue';
ctx.fill();
ctx.stroke();
ctx.beginPath();
ctx.arc(0, 0, radius, 0, 2 * Math.PI, false);
ctx.strokeStyle = 'yellow';
ctx.fillStyle = 'blue';
ctx.lineWidth = 50;
ctx.fill();
ctx.stroke();
}
function drawHand(ctx, pos, length, width) {
ctx.beginPath();
ctx.lineWidth = 30;
ctx.moveTo(-radius,0);
ctx.lineTo(radius, 0);
ctx.moveTo(-radius,150);
ctx.lineTo(radius, -150);
ctx.moveTo(-radius,-150);
ctx.lineTo(radius, 150);
ctx.moveTo(-radius,380);
ctx.lineTo(radius, -380);
ctx.moveTo(-radius,-380);
ctx.lineTo(radius, 380);
ctx.moveTo(0, -radius);
ctx.lineTo(0, radius);
ctx.stroke();
/*
ctx.globalCompositeOperation='destination-over';
ctx.font="20px Verdana";
ctx.fillStyle = 'white';
ctx.fillText("Explore Zero",180,180);
ctx.stroke();
ctx.globalCompositeOperation='source-over';*/
ctx.rotate(-pos);
}
</script>
</body>
</html>
Thanks in advance
Here's code to get you started:
You can style it to your specific needs
Create an in-memory canvas containing your wheel.
Create an in-memory canvas containing your spike-indicator.
Rotate the canvas and draw the wheel on the main canvas.
Draw the indicator on the main canvas.
Change the rotation angle for the next loop.
Repeat, repeat, repeat using requestAnimationFrame.
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var cw=canvas.width;
var ch=canvas.height;
var PI2=Math.PI*2;
var myData = [1,2,3,4,5,6,7,8,9,10,11,12];
var cx=150;
var cy=150;
var radius=150;
var wheel=document.createElement('canvas');
var wheelCtx=wheel.getContext('2d');
var indicator=document.createElement('canvas');
var indicatorCtx=indicator.getContext('2d');
var angle=PI2-PI2/4;
var myColor = [];
for(var i=0;i<myData.length;i++){ myColor.push(randomColor()); }
makeWheel();
makeIndicator();
requestAnimationFrame(animate);
function makeWheel(){
wheel.width=wheel.height=radius*2+2;
wheelCtx.lineWidth=1;
wheelCtx.font='24px verdana';
wheelCtx.textAlign='center';
wheelCtx.textBaseline='middle';
var cx=wheel.width/2;
var cy=wheel.height/2;
var sweepAngle=PI2/myData.length;
var startAngle=0;
for(var i=0;i<myData.length;i++){
// calc ending angle based on starting angle
var endAngle=startAngle+sweepAngle;
// draw the wedge
wheelCtx.beginPath();
wheelCtx.moveTo(cx,cy);
wheelCtx.arc(cx,cy,radius,startAngle,endAngle,false);
wheelCtx.closePath();
wheelCtx.fillStyle=myColor[i];
wheelCtx.strokeStyle='black';
wheelCtx.fill();
wheelCtx.stroke();
// draw the label
var midAngle=startAngle+(endAngle-startAngle)/2;
var labelRadius=radius*.85;
var x=cx+(labelRadius)*Math.cos(midAngle);
var y=cy+(labelRadius)*Math.sin(midAngle);
wheelCtx.fillStyle='gold';
wheelCtx.fillText(myData[i],x,y);
wheelCtx.strokeText(myData[i],x,y);
// increment angle
startAngle+=sweepAngle;
}
}
function makeIndicator(){
indicator.width=indicator.height=radius+radius/10;
indicatorCtx.font='18px verdana';
indicatorCtx.textAlign='center';
indicatorCtx.textBaseline='middle';
indicatorCtx.fillStyle='skyblue';
indicatorCtx.strokeStyle='blue';
indicatorCtx.lineWidth=1;
var cx=indicator.width/2;
var cy=indicator.height/2;
indicatorCtx.beginPath();
indicatorCtx.moveTo(cx-radius/8,cy);
indicatorCtx.lineTo(cx,cy-indicator.height/2);
indicatorCtx.lineTo(cx+radius/8,cy);
indicatorCtx.closePath();
indicatorCtx.fillStyle='skyblue'
indicatorCtx.fill();
indicatorCtx.stroke();
indicatorCtx.beginPath();
indicatorCtx.arc(cx,cy,radius/3,0,PI2);
indicatorCtx.closePath();
indicatorCtx.fill();
indicatorCtx.stroke();
indicatorCtx.fillStyle='blue';
indicatorCtx.fillText('Prizes',cx,cy);
}
function animate(time){
ctx.clearRect(0,0,cw,ch);
ctx.translate(cw/2,ch/2);
ctx.rotate(angle);
ctx.drawImage(wheel,-wheel.width/2,-wheel.height/2);
ctx.rotate(-angle);
ctx.translate(-cw/2,-ch/2);
ctx.drawImage(indicator,cw/2-indicator.width/2,ch/2-indicator.height/2)
angle+=PI2/360;
requestAnimationFrame(animate);
}
function randomColor(){
return('#'+Math.floor(Math.random()*16777215).toString(16));
}
body{ background-color: ivory; padding:10px; }
canvas{border:1px solid red;}
<canvas id="canvas" width=400 height=300></canvas>
You can just put the "wheel" image on the website and just rotate it.
document.getElementById("TheImage").style.transform = "rotate("+YourAngle+"deg)";
Also you will need to put the "pointer" image on top of "wheel" image. (you will not rotate this one)
This is a fiddle written in 20 minutes, hope it helps.
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
canvas.width = 500;
canvas.height = 500;
var lines = new Array();
lines[0] = new Array();
lines[0] = ["Prize 1","#000000"];
lines[1] = new Array();
lines[1] = ["Prize 2","#ffff00"];
lines[2] = new Array();
lines[2] = ["Prize 3","#ff00ff"];
lines[3] = new Array();
lines[3] = ["Prize 4","#00ffff"];
lines[4] = new Array();
lines[4] = ["Prize 5","#00ff00"];
var TO_RADIANS = Math.PI / 180;
var angle = 360 / lines.length; //to see how far apart the lines need to be
var angle_offset = 0; //this will determine the spinning
var angle_speed = 1; //degrees per cycle
var center_offset = 20; //the radius of your spinner in the middle
function animate() {
ctx.clearRect(0,0,canvas.width,canvas.height);
angle_offset+=angle_speed;
ctx.font="20px Verdana";
ctx.fillStyle="#000000";
for (i=0; i<lines.length; i++) {
ctx.fillStyle=lines[i][1];
ctx.save();
ctx.translate(canvas.width/2, canvas.height/2);
ctx.rotate((angle * i + angle_offset) * TO_RADIANS);
//Here you can also decorate with boxes and stuff
ctx.fillText(lines[i][0],center_offset,0);
ctx.restore();
}
requestAnimationFrame(animate);
}
animate();
<canvas id="canvas"></canvas>
I want to drag & drop text above image. For that I am using canvas. I am using this code
<img id="scream" src="http://127.0.0.1/demo/images.jpg" alt="The Scream" style="display:none;" width="220" height="277"><p>Canvas:</p>
<canvas id="canvas" width="300" height="300" style="border:1px solid #d3d3d3;">
Your browser does not support the HTML5 canvas tag.</canvas>
var c=document.getElementById("canvas");
var ctx1=c.getContext("2d");
var img=document.getElementById("scream");
ctx1.drawImage(img,10,10);
var canvas;
var ctx;
var x = 75;
var y = 50;
var dx = 5;
var dy = 3;
var WIDTH = 400;
var HEIGHT = 300;
var dragok = false,
text = "Hey there im moving!",
textLength = (text.length * 14)/2;
function rect(x,y,w,h) {
ctx.font = "14px Arial";
ctx.strokeText("Hey there im a moving!!", x, y);
}
function clear() {
ctx.clearRect(0, 0, WIDTH, HEIGHT);
}
function init() {
canvas = document.getElementById("canvas");
ctx = canvas.getContext("2d");
return setInterval(draw, 10);
}
function draw() {
clear();
ctx.fillStyle = "#FAF7F8";
ctx.fillStyle = "#444444";
rect(x - 15, y + 15, textLength, 30);
}
function myMove(e){
if (dragok){
x = e.pageX - canvas.offsetLeft;
y = e.pageY - canvas.offsetTop;
}
}
function myDown(e){
if (e.pageX < x + textLength + canvas.offsetLeft && e.pageX > x - textLength + canvas.offsetLeft && e.pageY < y + 15 + canvas.offsetTop &&
e.pageY > y -15 + canvas.offsetTop){
x = e.pageX - canvas.offsetLeft;
y = e.pageY - canvas.offsetTop;
dragok = true;
canvas.onmousemove = myMove;
}
}
function myUp(){
dragok = false;
canvas.onmousemove = null;
}
init();
canvas.onmousedown = myDown;
canvas.onmouseup = myUp;
I either able to show image or drag & drop text but I want both, please help me where I am wrong. You can check here:- http://jsfiddle.net/FWdSv/11/
When you're clearing the canvas, you're also clearing your image.
So the easy fix is to redraw the image in your draw function:
function draw() {
clear();
ctx.drawImage(img,0,0);
ctx.fillStyle = "#FAF7F8";
ctx.fillStyle = "#444444";
rect(x - 15, y + 15, textLength, 30);
}
Alternatively:
You could display your image underneath your canvas so it's not affected when you clear the canvas.
I am trying to create a floating circles effect using HTML5 and canvas. An example of what I'm going for can be seen on https://layervault.com/ You can see the example by going to the 4th slide (titled "Introducing LayerVault for iOS") in the slider. On that slide, lots of circles are floating up out of the object. So far in my code, I am only able to get 1 circle floating up. Any ideas on the approach I should take?
My Code so far:
$(document).ready(function() {
var canvas = $("#myCanvas").get(0);
var context = canvas.getContext("2d");
var circleColors = new Array();
circleColors[0]="#f0f";
circleColors[1]="#0f0";
circleColors[2]="#00f";
circleColors[3]="#f00";
function makeCircles() {
var posX = Math.floor(Math.random()*500);
var posY = 500;
var theCircleColor = circleColors[Math.floor(Math.random()*circleColors.length)];
function renderContent()
{
context.save();
context.fillStyle=theCircleColor;
context.beginPath();
context.arc(posX,posY,40,0,2*Math.PI);
context.fill();
context.restore();
}//end function renderContent
function animationLoop()
{
canvas.width = canvas.width;
renderContent();
posY -= 5;
if (posY < -40)
posY = 500;
setTimeout(animationLoop, 33);
}//end function animationLoop
animationLoop();
}//end function makeCircles
makeCircles();
});//end document ready
You need to make an array of circles, each circle needs its own X/Y/Color and potentially speed, so they move at different rates.
So each circle will be a javascript object with
{
posX: someValue,
posY: someValue,
color: someValue,
speed: someValue
};
Then we will add many of those to an array. Here's an example using your code:
var canvas = $("#myCanvas").get(0);
var context = canvas.getContext("2d");
var circleColors = new Array();
circleColors[0] = "#f0f";
circleColors[1] = "#0f0";
circleColors[2] = "#00f";
circleColors[3] = "#f00";
var circles = [];
function makeCircles() {
for (var i = 0; i < 20; i++) {
var circle = {
posX: Math.floor(Math.random() * 500),
posY: 500,
color: circleColors[Math.floor(Math.random() * circleColors.length)],
speed: Math.floor(Math.random()*5)
};
circles.push(circle);
}
function renderContent() {
for (var i = 0; i < circles.length; i++) {
var c = circles[i];
context.fillStyle = c.color;
context.beginPath();
context.arc(c.posX, c.posY, 40, 0, 2 * Math.PI);
context.fill();
}
} //end function renderContent
function animationLoop() {
canvas.width = canvas.width;
renderContent();
for (var i = 0; i < circles.length; i++) {
var c = circles[i];
c.posY -= c.speed;
if (c.posY < -40) c.posY = 500;
}
setTimeout(animationLoop, 33);
} //end function animationLoop
animationLoop();
} //end function makeCircles
makeCircles();
And here it is live:
http://jsfiddle.net/vTaLF/
I have a html5 canvas that draws a sound wave. I have set the background as an background image, however, I want this background image to repeat. Can anyone tell me how I would do this and what I need to add into my code:
var backgroundImage = new Image();
backgroundImage.src = 'http://www.samskirrow.com/client-kyra/images/main-bg.jpg';
var canvas;
var context;
function init(c) {
canvas = document.getElementById(c);
context = canvas.getContext("2d");
soundManager.onready(function() {
initSound(clientID, playlistUrl);
});
aniloop();
}
function aniloop() {
requestAnimFrame(aniloop);
drawWave();
}
function drawWave() {
var step = 10;
var scale = 60;
// clear
context.drawImage(backgroundImage, 0, 0);
// left wave
context.beginPath();
context.moveTo(0, 256);
for ( var i = 0; i < 256; i++) {
context.lineTo(6 * i, 257 + waveLeft[i] * 80.);
}
context.lineWidth = 1;
context.strokeStyle = "#000";
context.stroke();
// right wave
context.beginPath();
context.moveTo(0, 256);
for ( var i = 0; i < 256; i++) {
context.lineTo(6 * i, 256 + waveRight[i] * 80.);
}
context.lineWidth = 1;
context.strokeStyle = "#000";
context.stroke();
}
function updateWave(sound) {
waveLeft = sound.waveformData.left;
}
return {
init : init
};
})();
You can see this code in action here:
http://www.samskirrow.com/client-kyra
Use the canvas' createPattern function
const canvas = document.getElementById("canvas"),
context = canvas.getContext("2d"),
img = new Image();
img.src = 'https://www.google.nl/images/srpr/logo3w.png';
img.addEventListener('load', () => {
const ptrn = context.createPattern(img, 'repeat'); // Create a pattern with this image, and set it to "repeat".
context.fillStyle = ptrn;
context.fillRect(0, 0, canvas.width, canvas.height); // context.fillRect(x, y, width, height);
})
<canvas id="canvas" width="600px" height="600px"></canvas>
(This is the fastest of the 2 samples).
Or, try a manual implementation:
const canvas = document.getElementById("canvas"),
context = canvas.getContext("2d"),
img = new Image();
img.src = 'https://www.google.nl/images/srpr/logo3w.png';
img.addEventListener('load', () => {
for (let w = 0; w < canvas.width; w += img.width) {
for (let h = 0; h < canvas.height; h += img.height) {
context.drawImage(img, w, h);
}
}
})
<canvas id="canvas" width="600px" height="600px"></canvas>