1. Archimedes spiral
Archimedes spiral is also known as “constant velocity spiral”. When a point P moves along the moving ray OP at the same speed, the ray rotates around the point o at the same angular speed. The trajectory of point P is called “Archimedean spiral”.
The Cartesian coordinate equation of Archimedes spiral is as follows:
r=10*(1+t)
x=r*cos(t * 360)
y=r*sin(t *360)
Write the following HTML code.
function draw(id)
{
var canvas=document.getElementById(id);
if (canvas==null)
return false;
var context=canvas.getContext(‘2d’);
context.fillStyle=”#EEEEFF”;
context.fillRect(0,0,300,300);
context.strokeStyle=”red”;
context.lineWidth=2;
var dig=Math.PI/32;
context.beginPath();
context.moveTo(150,150);
for (var i=1;i<=256;i++)
{
x=150+5*i*dig*Math.sin(i*dig);
y=150+5*i*dig*Math.cos(i*dig);
context.lineTo(x,y);
}
context.stroke();
}