Develop Reference

want to style the all dots of pre built html canvas background

The code is different, I apologize may I didn't ask the question the right way, you can understand well in principle, When I'm hovering the dots get colours and connect to each other, other dots are invisible, I want that all dots should be visible all time. live example available on codepen, https://codepen.io/tati420/pen/RwBamQo?editors=1111
(function () {
var width,
height,
largeHeader,
canvas,
ctx,
points,
target,
animateHeader = true;
// Main
initHeader();
initAnimation();
addListeners();
function initHeader() {
width = window.innerWidth;
height = window.innerHeight;
target = { x: width / 2, y: height / 2 };
largeHeader = document.getElementById("large-header");
largeHeader.style.height = height + "px";
canvas = document.getElementById("demo-canvas");
canvas.width = width;
canvas.height = height;
ctx = canvas.getContext("2d");
// create points
points = [];
for (var x = 0; x < width; x = x + width / 20) {
for (var y = 0; y < height; y = y + height / 20) {
var px = x + (Math.random() * width) / 20;
var py = y + (Math.random() * height) / 20;
var p = { x: px, originX: px, y: py, originY: py };
points.push(p);
}
}
// for each point find the 5 closest points
for (var i = 0; i < points.length; i++) {
var closest = [];
var p1 = points[i];
for (var j = 0; j < points.length; j++) {
var p2 = points[j];
if (!(p1 == p2)) {
var placed = false;
for (var k = 0; k < 5; k++) {
if (!placed) {
if (closest[k] == undefined) {
closest[k] = p2;
placed = true;
}
}
}
for (var k = 0; k < 5; k++) {
if (!placed) {
if (getDistance(p1, p2) < getDistance(p1, closest[k])) {
closest[k] = p2;
placed = true;
}
}
}
}
}
p1.closest = closest;
}
// assign a circle to each point
for (var i in points) {
var c = new Circle(
points[i],
2 + Math.random() * 2,
"rgba(0,255,255,0.3)"
);
points[i].circle = c;
}
}
// Event handling
function addListeners() {
if (!("ontouchstart" in window)) {
window.addEventListener("mousemove", mouseMove);
}
window.addEventListener("scroll", scrollCheck);
window.addEventListener("resize", resize);
}
function mouseMove(e) {
var posx = (posy = 0);
if (e.pageX || e.pageY) {
posx = e.pageX;
posy = e.pageY;
} else if (e.clientX || e.clientY) {
posx =
e.clientX +
document.body.scrollLeft +
document.documentElement.scrollLeft;
posy =
e.clientY +
document.body.scrollTop +
document.documentElement.scrollTop;
}
target.x = posx;
target.y = posy;
}
function scrollCheck() {
if (document.body.scrollTop > height) animateHeader = false;
else animateHeader = true;
}
function resize() {
width = window.innerWidth;
height = window.innerHeight;
largeHeader.style.height = height + "px";
canvas.width = width;
canvas.height = height;
}
// animation
function initAnimation() {
animate();
for (var i in points) {
shiftPoint(points[i]);
}
}
function animate() {
if (animateHeader) {
ctx.clearRect(0, 0, width, height);
for (var i in points) {
// detect points in range
if (Math.abs(getDistance(target, points[i])) < 4000) {
points[i].active = 0.3;
points[i].circle.active = 0.6;
} else if (Math.abs(getDistance(target, points[i])) < 20000) {
points[i].active = 0.1;
points[i].circle.active = 0.3;
} else if (Math.abs(getDistance(target, points[i])) < 40000) {
points[i].active = 0.02;
points[i].circle.active = 0.1;
} else {
points[i].active = 0;
points[i].circle.active = 0;
}
drawLines(points[i]);
points[i].circle.draw();
}
}
requestAnimationFrame(animate);
}
function shiftPoint(p) {
TweenLite.to(p, 1 + 1 * Math.random(), {
x: p.originX - 50 + Math.random() * 100,
y: p.originY - 50 + Math.random() * 100,
ease: Circ.easeInOut,
onComplete: function () {
shiftPoint(p);
},
});
}
ctx.strokeStyle = "rgba(255,0,0," + p.active + ")";
// Canvas manipulation
function drawLines(p) {
if (!p.active) return;
for (var i in p.closest) {
ctx.beginPath();
ctx.moveTo(p.x, p.y);
ctx.lineTo(p.closest[i].x, p.closest[i].y);
ctx.strokeStyle = "rgba(0,255,255," + p.active + ")";
ctx.stroke();
}
}
function Circle(pos, rad, color) {
var _this = this;
// constructor
(function () {
_this.pos = pos || null;
_this.radius = rad || null;
_this.color = color || null;
})();
this.draw = function () {
if (!_this.active) return;
ctx.beginPath();
ctx.arc(_this.pos.x, _this.pos.y, _this.radius, 0, 2 * Math.PI, false);
ctx.fillStyle = "rgba(0,255,0," + _this.active + ")";
ctx.fill();
};
}
// Util
function getDistance(p1, p2) {
return Math.pow(p1.x - p2.x, 2) + Math.pow(p1.y - p2.y, 2);
}
})();

If I understand your question correctly, you just want to make sure that every point.active = 1 and point.circle.active = 1:
function animate() {
if (animateHeader) {
ctx.clearRect(0, 0, width, height);
for (var i in points) {
points[i].active = 1;
points[i].circle.active = 1;
drawLines(points[i]);
points[i].circle.draw();
}
}
requestAnimationFrame(animate);
}

Why won't the image load

What is wrong with the code, I can't find the problem. I think it's because of the drawFrame and loadImage function, but I don't know. So is there a way to make the image load and you will still be able to move it around and shoot?
And when I try to remove the drawFrame function nothing would work. And if posiible is there a way to change the bullet from squares to circles?
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta charset="UTF-8">
<style>
html,
body {
width: 100%;
height: 100%;
margin: 0;
}
canvas {
cursor: crosshair;
background-color: cornflowerblue;
}
</style>
</head>
<body>
<canvas id="Trump"></canvas>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script>
(async function main() {
var canvas = document.getElementById('Trump');
if (!canvas.getContext) return;
var ctx = canvas.getContext('2d');
ctx.canvas.width = window.innerWidth;
ctx.canvas.height = window.innerHeight;
//const fps = 60;
const ronaNum = 30; // number of particles at start
const ronaSize = 70; // corona size
const ronaSpeed = 100; // speed
let chinabmg;
function draw() {
$("canvas").one("click", function () {
chinabmg = new sound("stankytrumpchina.mp3");
chinabmg.play();
});
//mutes when clicked on m
document.body.onkeyup = function (e) {
if (e.keyCode == 77) { chinabmg.stop() }
};
//compatability
var requestAnimationFrame = window.requestAnimationFrame || //Chromium
window.webkitRequestAnimationFrame || //Webkit
window.mozRequestAnimationFrame || //Mozilla Geko
window.oRequestAnimationFrame || //Opera Presto
window.msRequestAnimationFrame || //IE Trident?
function (callback) { //Fallback function
window.setTimeout(callback, 1000 / 60);
};
var DrawX = 0;
var DrawY = 0;
var time = 0;
var width = canvas.width;
var height = canvas.height;
var offTop = canvas.offsetTop;
var offLeft = canvas.offsetLeft;
var rectWidth = 15;
var rectHeight = 15;
var speed = 1;
var x = width / 2;
var y = height / 2;
var size = 30;
var id = 0;
var bulletId = 0;
function sound(src) {
this.sound = document.createElement("audio");
this.sound.src = src;
this.sound.setAttribute("preload", "auto");
this.sound.setAttribute("controls", "none");
this.sound.setAttribute("loop", "auto");
this.sound.style.display = "none";
document.body.appendChild(this.sound);
this.play = function () {
this.sound.play();
}
this.stop = function () {
this.sound.pause();
}
}
function player(id, color, size, x, y) {
this.id = id;
this.color = color;
this.size = size;
this.x = x;
this.y = y;
this.speed = speed;
}
var playerList = [];
function addPlayer(color, size, x, y) {
playerList[id] = new player(id, color, size, x, y);
id += 1;
}
addPlayer("blue", size, width / 2 - 50, height / 2);
var pressedKeys = [];
function moveLeft(checkId, checkX, checkY, cSize, cSpeed, cKey) {
var x = checkX - cSpeed;
var y = checkY - cSpeed;
var x2 = checkX + cSize + cSpeed;
var y2 = checkY + cSize + cSpeed;
if (x > 0) {
playerList[checkId].x = checkX - cSpeed;
} else {
playerList[checkId].x = 0;
}
}
function moveUp(checkId, checkX, checkY, cSize, cSpeed, cKey) {
var x = checkX - cSpeed;
var y = checkY - cSpeed;
var x2 = checkX + cSize + cSpeed;
var y2 = checkY + cSize + cSpeed;
if (y > 0) {
playerList[checkId].y = checkY - cSpeed;
} else {
playerList[checkId].y = 0;
}
}
function moveRight(checkId, checkX, checkY, cSize, cSpeed, cKey) {
var x = checkX - cSpeed;
var y = checkY - cSpeed;
var x2 = checkX + cSize + cSpeed;
var y2 = checkY + cSize + cSpeed;
if (x2 < width) {
playerList[checkId].x = checkX + cSpeed;
} else {
playerList[checkId].x = width - cSize;
}
}
function moveDown(checkId, checkX, checkY, cSize, cSpeed, cKey) {
var x = checkX - cSpeed;
var y = checkY - cSpeed;
var x2 = checkX + cSize + cSpeed;
var y2 = checkY + cSize + cSpeed;
if (y2 < height) {
playerList[checkId].y = checkY + cSpeed;
} else {
playerList[checkId].y = height - cSize;
}
}
function Move(checkId, checkX, checkY, cSize, cSpeed, cKey) {
if (checkId === 0) {
switch (cKey) {
case 65:
// left
moveLeft(checkId, checkX, checkY, cSize, cSpeed, cKey);
break;
case 87:
// up
moveUp(checkId, checkX, checkY, cSize, cSpeed, cKey);
break;
case 68:
// right
moveRight(checkId, checkX, checkY, cSize, cSpeed, cKey);
break;
case 83:
// down
moveDown(checkId, checkX, checkY, cSize, cSpeed, cKey);
break;
default:
return; // exit this handler for other keys
}
}
}
var validKeys = [];
validKeys[0] = "65,87,68,83-107,109,80";
// == KEYDOWN ==
$(document.body).keydown(function (e) {
e.preventDefault();
//go through all players
$.each(playerList, function (i, currentPlayer) {
if (validKeys[currentPlayer.id].indexOf(e.which) == -1) return true;
if (!pressedKeys[e.which]) {
//set interval for the function
pressedKeys[e.which] = setInterval(function () {
Move(currentPlayer.id, currentPlayer.x, currentPlayer.y, currentPlayer.size, currentPlayer.speed, e.which);
}, 5);
}
});
});
// == KEYUP ==
$(document.body).keyup(function (e) {
if (pressedKeys[e.which]) {
clearInterval(pressedKeys[e.which]);
delete pressedKeys[e.which];
}
});
//=============================== SHOOTING ===============================
//Bullets
function bullet(id, color, size, speed, x, y, eX, eY) {
this.id = id;
this.color = color;
this.size = size;
this.x = x;
this.y = y;
this.eX = eX;
this.eY = eY;
this.velocityX = 1;
this.velocityY = 1;
this.speed = 9;
}
var bulletList = [];
function addBullet(color, bsize, bspeed, x, y, eX, eY) {
bulletList[bulletId] = new bullet(bulletId, color, bsize, 9, x, y, eX, eY);
bulletId += 1;
}
function updateBullet(bullet, player) {
var dx = (bullet.eX - player.x);
var dy = (bullet.eY - player.y);
var mag = Math.sqrt(dx * dx + dy * dy);
bullet.velocityX = (dx / mag) * 9;
bullet.velocityY = (dy / mag) * 9;
bullet.x += bullet.velocityX;
bullet.y += bullet.velocityY;
}
// Add event listener for `click` events.
canvas.onmousedown = function (e) {
addBullet("#696969", 10, 2, playerList[0].x, playerList[0].y, e.x, e.y);
};
//corona part
let corona = [];
createCoronaParticles();
// game loop
//setInterval(update, 1000 / fps);
function createCoronaParticles() {
corona = [];
let cx, cy;
for (var i = 0; i < ronaNum; i++) {
do {
cx = Math.floor(Math.random() * canvas.width);
cy = Math.floor(Math.random() * canvas.height);
} while (noSpawnOnFigure(canvas.height / 2, canvas.width / 2, cy, cx) < ronaSize * 5);
corona.push(newParticle(cx, cy));
}
}
function noSpawnOnFigure(cy1, cx1, cy2, cx2) {
return Math.sqrt(Math.pow(cy2 - cy1, 2) + Math.pow(cx2 - cx1, 2));
}
function newParticle(cx, cy) {
let rona = {
ca: Math.random() * Math.PI * 2, //radians
cr: ronaSize / 2,
cx: cx,
cy: cy,
cxv: Math.random() * ronaSpeed / 60 * (Math.random() < 0.5 ? 1 : -1),
cyv: Math.random() * ronaSpeed / 60 * (Math.random() < 0.5 ? 1 : -1)
};
return rona;
}
// function update() {
// }
// ======= DRAWING =======
function drawFrame() {
requestAnimationFrame(drawFrame);
ctx.font = "15pt Georgia"; // sets the font and font size of the text
ctx.clearRect(0, 0, width, height);
$.each(playerList, function (index, currentPlayer) {
//debug
//draw players
function loadImage(path) {
let image = new Image();
let promise = new Promise((resolve, reject) => {
image.onload = () => resolve(image);
image.onerror = reject
});
image.src = path;
return promise;
}
loadImage.src = 'trump.gif';
});
//draw bullets
$.each(bulletList, function (index, bullet) {
updateBullet(bullet, playerList[0]);
ctx.fillStyle = bullet.color;
ctx.fillRect(bullet.x, bullet.y, bullet.size, bullet.size);
});
// canvas
//ctx.clearRect(0, 0, canvas.width, canvas.height);
// draw corona particles
ctx.strokeStyle = "rgb(150, 0, 0)";
ctx.lineWidth = 20;
let ca, cr, cx, cy;
for (let i = 0; i < corona.length; i++) {
// get properties
ca = corona[i].ca;
cr = corona[i].cr;
cx = corona[i].cx;
cy = corona[i].cy;
// draw path
ctx.beginPath();
ctx.fillStyle = "rgb(200, 0, 0)"
ctx.moveTo(
cx + cr * Math.cos(ca),
cy + cr * Math.sin(ca)
);
// draw circle
for (let j = 1; j < 180; j++) {
ctx.lineTo(
cx + cr * Math.cos(ca + j * Math.PI * 2 / 180),
cy + cr * Math.sin(ca + j * Math.PI * 2 / 180)
);
}
ctx.closePath();
ctx.stroke();
ctx.fill();
// move particles
corona[i].cx += corona[i].cxv;
corona[i].cy += corona[i].cyv;
// particle edge of screen
if (corona[i].cx < 0 - corona[i].cr) {
corona[i].cx = canvas.width + corona[i].cr;
} else if (corona[i].cx > canvas.width + corona[i].cr) {
corona[i].cx = 0 - corona[i].cr
}
if (corona[i].cy < 0 - corona[i].cr) {
corona[i].cy = canvas.height + corona[i].cr;
} else if (corona[i].cy > canvas.height + corona[i].cr) {
corona[i].cy = 0 - corona[i].cr
}
}
}
drawFrame();
}
$(draw);
}
)();
</script>
</body>
</html>

//draw players
function loadImage(path) {
let image = new Image();
let promise = new Promise((resolve, reject) => {
image.onload = () => resolve(image);
image.onerror = reject
});
image.src = path;
//Add the following line
ctx.drawImage(image,playerList[0].x,playerList[0].y);
return promise;
}
// change loadImage.src = 'trump.gif' into this
loadImage('trump.gif');

How can I reverse the direction of this square after it reaches a certain value?

I'm trying to create an idle animation where the red rectangle moves back and forth slightly in a loop. For some reason once it reaches the specified threshhold instead of proceeding to move in the opposite direction, it just stops.
What did I do wrong?
<canvas id="myCanvas" width="1500" height="500" style="border:1px solid #c3c3c3;">
Your browser does not support the canvas element.
</canvas>
<script>
var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
// Spaceship structure
var shipWidth = 250;
var shipHeight = 100;
// Canvas parameters
var cWidth = canvas.width;
var cHeight = canvas.height;
// Positioning variables
var centerWidthPosition = (cWidth / 2) - (shipWidth / 2);
var centerHeightPosition = (cHeight / 2) - (shipHeight / 2);
var requestAnimationFrame = window.requestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.msRequestAnimationFrame;
function drawShip(){
ctx.clearRect(0, 0, cWidth, cHeight);
ctx.fillStyle = "#FF0000";
ctx.fillRect(centerWidthPosition,centerHeightPosition,shipWidth,shipHeight);
centerWidthPosition--;
if (centerWidthPosition < 400){
++centerWidthPosition;
}
requestAnimationFrame(drawShip);
}
drawShip();
</script>

#TheAmberlamps explained why it's doing that. Here I offer you a solution to achieve what I believe you are trying to do.
Use a velocity variable that changes magnitude. X position always increases by velocity value. Velocity changes directions at screen edges.
// use a velocity variable
var xspeed = 1;
// always increase by velocity
centerWidthPosition += xspeed;
// screen edges are 0 and 400 in this example
if (centerWidthPosition > 400 || centerWidthPosition < 0){
xspeed *= -1; // change velocity direction
}
I added another condition in your if that causes the object to bounce back and forth. Remove the selection after || if you don't want it doing that.

Your function is caught in a loop; once centerWidthPosition reaches 399 your conditional makes it increment back up to 400, and then it decrements back to 399.

here is another one as a brain teaser - how would go by making this animation bounce in the loop - basically turn text into particles and then reverse back to text and reverse back to particles and back to text and so on and on and on infinitely:
var random = Math.random;
window.onresize = function () {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
};
window.onresize();
var ctx = canvas.getContext('2d');
ctx.font = 'bold 50px "somefont"';
ctx.textBaseline = 'center';
ctx.fillStyle = 'rgba(255,255,255,1)';
var _particles = [];
var particlesLength = 0;
var currentText = "SOMETEXT";
var createParticle = function createParticle(x, y) {_particles.push(new Particle(x, y));};
var checkAlpha = function checkAlpha(pixels, i) {return pixels[i * 4 + 3] > 0;};
var createParticles = function createParticles() {
var textSize = ctx.measureText(currentText);
ctx.fillText(currentText,Math.round((canvas.width / 2) - (textSize.width / 2)),Math.round(canvas.height / 2));
var imageData = ctx.getImageData(1, 1, canvas.width, canvas.height);
var pixels = imageData.data;
var dataLength = imageData.width * imageData.height;
for (var i = 0; i < dataLength; i++) {
var currentRow = Math.floor(i / imageData.width);
var currentColumn = i - Math.floor(i / imageData.height);
if (currentRow % 2 || currentColumn % 2) continue;
if (checkAlpha(pixels, i)) {
var cy = ~~(i / imageData.width);
var cx = ~~(i - (cy * imageData.width));
createParticle(cx, cy);
}}
particlesLength = _particles.length;
};
var Point = function Point(x, y) {
this.set(x, y);
};
Point.prototype = {
set: function (x, y) {
x = x || 0;
y = y || x || 0;
this._sX = x;
this._sY = y;
this.reset();
},
add: function (point) {
this.x += point.x;
this.y += point.y;
},
multiply: function (point) {
this.x *= point.x;
this.y *= point.y;
},
reset: function () {
this.x = this._sX;
this.y = this._sY;
return this;
},
};
var FRICT = new Point(0.98);//set to 0 if no flying needed
var Particle = function Particle(x, y) {
this.startPos = new Point(x, y);
this.v = new Point();
this.a = new Point();
this.reset();
};
Particle.prototype = {
reset: function () {
this.x = this.startPos.x;
this.y = this.startPos.y;
this.life = Math.round(random() * 300);
this.isActive = true;
this.v.reset();
this.a.reset();
},
tick: function () {
if (!this.isActive) return;
this.physics();
this.checkLife();
this.draw();
return this.isActive;
},
checkLife: function () {
this.life -= 1;
this.isActive = !(this.life < 1);
},
draw: function () {
ctx.fillRect(this.x, this.y, 1, 1);
},
physics: function () {
if (performance.now()<nextTime) return;
this.a.x = (random() - 0.5) * 0.8;
this.a.y = (random() - 0.5) * 0.8;
this.v.add(this.a);
this.v.multiply(FRICT);
this.x += this.v.x;
this.y += this.v.y;
this.x = Math.round(this.x * 10) / 10;
this.y = Math.round(this.y * 10) / 10;
}
};
var nextTime = performance.now()+3000;
createParticles();
function clearCanvas() {
ctx.fillStyle = 'rgba(0,0,0,1)';
ctx.fillRect(0, 0, canvas.width, canvas.height);
}
(function clearLoop() {
clearCanvas();
requestAnimationFrame(clearLoop);
})();
(function animLoop(time) {
ctx.fillStyle = 'rgba(255,255,255,1)';
var isAlive = true;
for (var i = 0; i < particlesLength; i++) {
if (_particles[i].tick()) isAlive = true;
}
requestAnimationFrame(animLoop);
})();
function resetParticles() {
for (var i = 0; i < particlesLength; i++) {
_particles[i].reset();
}}

Scroll Image in canvas from top to bottom

How can I scroll Image from top to bottom position. Currently, it is moving from left to right and also tried interchanging the "xpos" and "y" value but the Image is getting distorted .Any help would be appreciated.
(function() {
window.requestAnimationFrame = window.requestAnimationFrame
|| window.webkitRequestAnimationFrame
|| window.mozRequestAnimationFrame
|| function(callback) { window.setTimeout(callback, 1000 / 60); };
var canvas = document.getElementById('bg');
var context = canvas.getContext('2d');
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
var looping = false;
var totalSeconds = 0;
var img = new Image();
img.onload = imageLoaded;
img.src = 'https://preview.ibb.co/dpQ6Ak/test.jpg';
function imageLoaded() {
draw(0);
startStop();
}
var lastFrameTime = 0;
function startStop() {
looping = !looping;
if (looping) {
lastFrameTime = Date.now();
requestAnimationFrame(loop);
}
}
function loop() {
if (!looping) {
return;
}
requestAnimationFrame(loop);
var now = Date.now();
var deltaSeconds = (now - lastFrameTime) / 1000;
lastFrameTime = now;
draw(deltaSeconds);
}
function draw(delta) {
totalSeconds += delta;
var vx = 100; // the background scrolls with a speed of 100 pixels/sec
var numImages = Math.ceil(canvas.width / img.width) + 1;
var xpos = totalSeconds * vx % img.width;
context.save();
context.translate(-xpos, 0);
for (var i = 0; i < numImages; i++) {
context.drawImage(img, i * img.width, 0);
}
context.restore();
}
}());
<canvas id="bg" ></canvas>

I guess this is your answer
(function() {
window.requestAnimationFrame = window.requestAnimationFrame
|| window.webkitRequestAnimationFrame
|| window.mozRequestAnimationFrame
|| function(callback) { window.setTimeout(callback, 1000 / 60); };
var canvas = document.getElementById('bg');
var context = canvas.getContext('2d');
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
var looping = false;
var totalSeconds = 0;
var img = new Image();
img.onload = imageLoaded;
img.src = 'https://preview.ibb.co/dpQ6Ak/test.jpg';
function imageLoaded() {
draw(0);
startStop();
}
var lastFrameTime = 0;
function startStop() {
looping = !looping;
if (looping) {
lastFrameTime = Date.now();
requestAnimationFrame(loop);
}
}
function loop() {
if (!looping) {
return;
}
requestAnimationFrame(loop);
var now = Date.now();
var deltaSeconds = (now - lastFrameTime) / 1000;
lastFrameTime = now;
draw(deltaSeconds);
}
function draw(delta) {
totalSeconds += delta;
var vx = 100; // the background scrolls with a speed of 100 pixels/sec
var numImages = Math.ceil(canvas.height / img.height) + 1;
var xpos = totalSeconds * vx % img.height;
context.save();
context.translate( 0,xpos);
for (var i = 0; i < numImages; i++) {
context.drawImage(img, 0,-(i * img.height));
}
context.restore();
}
}());
<canvas id="bg" ></canvas>

Drawing an image moving in any direction
var imageScroll = scrollImage("myCan",1.57,60);
setTimeout(randomScroll,10000);
function randomScroll(){
imageScroll.setSpeed( Math.random() * 60 + 20)
.setDirection( Math.random() * Math.PI * 2);
setTimeout(randomScroll,1000 + 2000 * Math.random());
}
function scrollImage(canvasId, direction, speed, URL){
var w, h, iW, iH; // alias for width and height, an image W H
var x, y; // current image pos;
var lastTime; // to track frame time
var stop = false; // when true stop
const rAF = requestAnimationFrame; // Alias
const canvas = document.getElementById(canvasId);
if (canvas === null) { throw new ReferenceError("Can not find canvas with id : '" + canvasId + "'") }
const ctx = canvas.getContext('2d');
const img = new Image;
w = canvas.width = innerWidth;
h = canvas.height = innerHeight;
x = y = lastTime = 0;
lastTime = 0;
img.src = URL ? URL : 'https://preview.ibb.co/dpQ6Ak/test.jpg';
img.onload = () => {
iW = img.width;
iH = img.height;
loop(0)
}
function loop(time) {
var fTime = (time - lastTime) / 1000; // get frame time
lastTime = time;
x += Math.cos(direction) * speed * fTime ; // update position
y += Math.sin(direction) * speed * fTime ;
drawImageRep(x, y); // draw image at x,y
if (!stop){ requestAnimationFrame(loop) }
}
function drawImageRep(x,y){
x = ((x % iW) + iW) % iW;
y = ((y % iH) + iH) % iH;
for(var iy = y - iH; iy < h; iy += iH){
for(var ix = x - iW; ix < w; ix += iW){
ctx.drawImage(img, ix, iy);
}
}
}
return {
stop(){stop = true; return this },
setSpeed(nSpeed){ speed = nSpeed; return this },
setDirection(nDirection) { direction = nDirection; return this },
}
}
<canvas id="myCan"></canvas>

Slowing movement of image on canvas

The Problem
I am creating a game that involves dodging projectiles. The player is in control of an image of a ship and I dont want the ship to move exactly together as this looks very unrealistic.
The Question
Is there a way to control how fast the image moves, how can i slow the movemnt of the image down?
The Code
var game = create_game();
game.init();
//music
var snd = new Audio("Menu.mp3");
snd.loop = true;
snd.play();
document.getElementById('mute').addEventListener('click', function (evt) {
if ( snd.muted ) {
snd.muted = false
evt.target.innerHTML = 'mute'
}
else {
snd.muted = true
evt.target.innerHTML = 'unmute'
}
})
function create_game() {
debugger;
var level = 1;
var projectiles_per_level = 1;
var min_speed_per_level = 1;
var max_speed_per_level = 2;
var last_projectile_time = 0;
var next_projectile_time = 0;
var width = 600;
var height = 500;
var delay = 1000;
var item_width = 30;
var item_height = 30;
var total_projectiles = 0;
var projectile_img = new Image();
var projectile_w = 30;
var projectile_h = 30;
var player_img = new Image();
var c, ctx;
var projectiles = [];
var player = {
x: 200,
y: 400,
score: 0
};
function init() {
projectile_img.src = "projectile.png";
player_img.src = "player.png";
level = 1;
total_projectiles = 0;
projectiles = [];
c = document.getElementById("c");
ctx = c.getContext("2d");
ctx.fillStyle = "#ff6600";
ctx.fillRect(0, 0, 500, 600);
c.addEventListener("mousemove", function (e) {
//moving over the canvas.
var bounding_box = c.getBoundingClientRect();
player.x = (e.clientX - bounding_box.left) * (c.width / bounding_box.width) - player_img.width / 2;
}, false);
setupProjectiles();
requestAnimationFrame(tick);
}
function setupProjectiles() {
var max_projectiles = level * projectiles_per_level;
while (projectiles.length < max_projectiles) {
initProjectile(projectiles.length);
}
}
function initProjectile(index) {
var max_speed = max_speed_per_level * level;
var min_speed = min_speed_per_level * level;
projectiles[index] = {
x: Math.round(Math.random() * (width - 2 * projectile_w)) + projectile_w,
y: -projectile_h,
v: Math.round(Math.random() * (max_speed - min_speed)) + min_speed,
delay: Date.now() + Math.random() * delay
}
total_projectiles++;
}
function collision(projectile) {
if (projectile.y + projectile_img.height < player.y + 74) {
return false;
}
if (projectile.y > player.y + 74) {
return false;
}
if (projectile.x + projectile_img.width < player.x + 177) {
return false;
}
if (projectile.x > player.x + 177) {
return false;
}
return true;
}
function maybeIncreaseDifficulty() {
level = Math.max(1, Math.ceil(player.score / 10));
setupProjectiles();
}
function tick() {
var i;
var projectile;
var dateNow = Date.now();
c.width = c.width;
for (i = 0; i < projectiles.length; i++) {
projectile = projectiles[i];
if (dateNow > projectile.delay) {
projectile.y += projectile.v;
if (collision(projectile)) {
initProjectile(i);
player.score++;
} else if (projectile.y > height) {
initProjectile(i);
} else {
ctx.drawImage(projectile_img, projectile.x, projectile.y);
}
}
}
ctx.font = "bold 24px sans-serif";
ctx.fillStyle = "#ff6600";
ctx.fillText(player.score, c.width - 50, 50);
ctx.fillText("Level: " + level, 20, 50);
ctx.drawImage(player_img, player.x, player.y);
maybeIncreaseDifficulty();
requestAnimationFrame(tick);
}
return {
init: init
};
}
https://jsfiddle.net/a6nmy804/4/ (Broken)

Throttle the player's movement using a "timeout" countdown
Create a global var playerFreezeCountdown=0.
In mousemove change player.x only if playerFreezeCountdown<=0.
If playerFreezeCountdown>0 you don't change player.x.
If playerFreezeCountdown<=0 you both change player.x and also set playerFreezeCountdown to a desired "tick timeout" value: playerFreezeCountdown=5. This timeout will cause prevent the player from moving their ship until 5 ticks have passed.
In tick, always decrement playerFreezeCountdown--. This will indirectly allow a change to player.x after when playerFreezeCountdown is decremented to zero or below zero.