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app.js
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app.js
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// helper function
const RADIUS = 20;
function degToRad(degrees) {
var result = Math.PI / 180 * degrees;
return result;
}
// setup of the canvas
var canvas = document.querySelector('canvas');
var ctx = canvas.getContext('2d');
var x = 50;
var y = 50;
function canvasDraw() {
ctx.fillStyle = "black";
ctx.fillRect(0, 0, canvas.width, canvas.height);
ctx.fillStyle = "#f00";
ctx.beginPath();
ctx.arc(x, y, RADIUS, 0, degToRad(360), true);
ctx.fill();
}
canvasDraw();
// pointer lock object forking for cross browser
canvas.requestPointerLock = canvas.requestPointerLock ||
canvas.mozRequestPointerLock;
document.exitPointerLock = document.exitPointerLock ||
document.mozExitPointerLock;
canvas.onclick = function() {
canvas.requestPointerLock();
};
// pointer lock event listeners
// Hook pointer lock state change events for different browsers
document.addEventListener('pointerlockchange', lockChangeAlert, false);
document.addEventListener('mozpointerlockchange', lockChangeAlert, false);
function lockChangeAlert() {
if (document.pointerLockElement === canvas ||
document.mozPointerLockElement === canvas) {
console.log('The pointer lock status is now locked');
document.addEventListener("mousemove", updatePosition, false);
} else {
console.log('The pointer lock status is now unlocked');
document.removeEventListener("mousemove", updatePosition, false);
}
}
var tracker = document.getElementById('tracker');
var animation;
function updatePosition(e) {
x += e.movementX;
y += e.movementY;
if (x > canvas.width + RADIUS) {
x = -RADIUS;
}
if (y > canvas.height + RADIUS) {
y = -RADIUS;
}
if (x < -RADIUS) {
x = canvas.width + RADIUS;
}
if (y < -RADIUS) {
y = canvas.height + RADIUS;
}
tracker.textContent = "X position: " + x + ", Y position: " + y;
if (!animation) {
animation = requestAnimationFrame(function() {
animation = null;
canvasDraw();
});
}
}