How to convert x,y coordinates to an angle?

Question

Microsoft provide an excellent SVG gradient maker so IE9 can also have \"CSS3\" gradients (click Custom).

I currently utilise their logic for my Fireworks and Dreamw

Answer 1

var x,x1,x2,y,y1,y2;
var cells = 'cell0';
		var h,w;
		var cx,cy;
		var dx,dy;
		var derajat;
		var deg;
		var ang;
		var light;
		var control;
			function mouse_watch(event){
				x = event.clientX;
				y = event.clientY;
				cell_data(cells);
				koordinat(x2,y2);
				busur(derajat);
			}
			function koordinat(x2,y2){
				x2 = x-cx;
				y2 = y-cy;
				yk = y2;
				xk = x2;
			}
			function busur(derajat){

				y1 = Math.sqrt((Math.abs(yk)*Math.abs(yk))+(Math.abs(xk)*(Math.abs(xk))));
				x1 = 0;
				dy = yk-y1;
				dx = xk-x1;
				rad = Math.atan2(dy, dx);
				derajat = rad * (360 / Math.PI);
				cell = document.getElementById(cells);
				ang = cell.getElementsByClassName('angle0')[0];
				ang.style.transform = 'rotate('+derajat+'deg)';
				light = ang.getElementsByClassName('points')[0];
				light.style.height = y1+'px';
			}
			function cell_data(cells){
				cell = document.getElementById(cells);
				h = Number(cell.style.height.replace('px',''));
				w = Number(cell.style.width.replace('px',''));
				cy = Number(cell.style.top.replace('px',''))+h/2;
				cx = Number(cell.style.left.replace('px',''))+w/2;
			}

			.preview_engine{
				position: absolute;
				top: 0;
				left: 0;
				padding: 10px;
				background-color: #2E8AE6;
				color: white;
			}
			body{
				cursor: default;
				width: 100%;
				height: 100%;
				font-family: Arial;
				font-size: 12px;
			}
			.fieldwork{
				width: 100%;
				height: 100%;
				position: absolute;
				top: 0px;
				left: 0px;
			}
			.cell{
				position: relative;
				transition : width 2s, height 2s, top 2s, left 2s;
				background-color: red;
			}
			.angle0{
				width: 200px;
				height: 200px;
				position: absolute;
				top: -75px;
				left: -75px;
				background-color: green;
				border-radius: 50%;
				opacity: 0.5;
				transition : width 2s, height 2s, top 2s, left 2s;
			}
			.points{
				width: 10px;
				height: 10px;
				position: absolute;
				left: 95px;
				top: 95px;
				background-color: red;
				border-radius: 1em;
				opacity: none;
			}