CHAPTER 5
} Close for loop
} Close function
function Polycard(sx,sy,rad,n) { Function header for
Polycard
this.sx = sx; Set up the x
coordinate
this.sy = sy; ... the y
this.rad = rad; ...the polygon radius
this.draw = drawpoly; ...how to draw
this.n = n; ...number of sides
this.angle = (2*Math.PI)/n Compute and store
the angle
} Close the function
function drawpoly() { Function header
ctx.fillStyle= frontbgcolor; Set the front
background
ctx.fillRect(this.sx-2*this.rad,this.sy-
2*this.rad,4*this.rad,4*this.rad);
The corner of the
rectangle is up and to
the left of the center
of the polygon
ctx.beginPath(); Start the path
ctx.fillStyle=polycolor; Change to color for
polygon
var i; Index variable
var rad = this.rad; Extract the radius
ctx.moveTo(this.sx+rad*Math.cos(-
.5*this.angle),this.sy+rad*Math.sin(-.5*this.angle));
Move up to the first
point
