JSFiddle - React, Tailwind, and code Playground
HTML
<body>
<h1>Rotation</h1>
<div id="graph1"></div>
<div id="marker">Wherever you click, it rotates to here</div>
</body>
CSS
#graph1 {
position:absolute;
top:100px;
left:50px;
width:400px;
height:400px;
background-image:url('http://www.showmethemath.com/Math_Practice/coordinateGridSquareScaleOf2.gif');
background-position:center center;
background-size:contain;
background-repeat:no-repeat;
transition:transform 1s ease;
transform:rotate(30deg);
transform-origin:50% 50%;
border-radius:50%;
}
#marker {
position: absolute;
top:300px;
left:450px;
border-top:1px solid black;
}
JavaScript
$(function () {
$('body').on('click', '#graph1', function (e) {
console.log('********************');
//get mouse position relative to div and center of div for polar origin
var pos = getMousePosAndCenter(e, 'graph1');
//get the current degrees of rotation from the css
var currentRotationDegrees = getCSSRotation('#graph1');
console.log('CSS Rotation Value: ' + currentRotationDegrees);
//current rotation in radians
var currentRotationRadians = radians(currentRotationDegrees);
//radians where clicked
var clickRadiansFromZero = Math.atan2(pos.y - pos.originY, pos.x - pos.originX);
//degrees the click is offset from 0 origin
var offsetDegrees = degrees(clickRadiansFromZero);
//how many degrees to rotate in css to put the mouse click at 0
var degreesToZero;
if (offsetDegrees >= 0)
degreesToZero = currentRotationDegrees - Math.abs(offsetDegrees);
else
degreesToZero = currentRotationDegrees + Math.abs(offsetDegrees);
console.log("Degrees to Zero: " + degreesToZero);
//distance in pixels from origin
var distance = calculateDistance(pos.originX, pos.originY, pos.x, pos.y);
console.log("Distance From Origin(px): " + distance);
$('#graph1').css('transform','rotate(' + degreesToZero + 'deg)')
});
});
function getMousePosAndCenter(e, id) {
var rect = document.getElementById(id).getBoundingClientRect();
return {
x: (((e.clientX - rect.left) / rect.width) * rect.width) + 0.5 << 0,
y: (((e.clientY - rect.top) / rect.height) * rect.height) + 0.5 << 0,
originY: (rect.height / 2),
originX: (rect.width / 2)
};
}
function radians(degrees) {
return degrees * Math.PI / 180;
};
function degrees(radians) {
return radians * 180 / Math.PI;
};
function calculateDistance(originX, originY, mouseX, mouseY) {
return...