Drawing a circle with triangles WebGL

Question

I'm new to WebGL and was trying to draw a circle with triangle_fan.

I set up the variables

var pi = 3.14159;
var x = 2*pi/100;
var y = 2*pi/100;
var r = 0.05;

points = [ vec2(0.4, 0.8) ]; //establish origin

And then drew the circle using this for loop.

for(var i = 0.4; i < 100; i++){
    points.push(vec2(r*Math.cos(x*i), r*Math.sin(y*i)));
    points.push(vec2(r*Math.cos(x*(i+1)), r*Math.sin(y*(i+1))));
}

The issue is that I am actually pushing in the second point again when i increases which I don't want to do.

Also, the image below is that is drawn :/

Answer 1

I don't have enough reputation to comment on mlkn's answer, but I think there was one piece he was missing. Here's how I ended up using his example

vec2 center = vec2(cX, cY); 

points.push(center);
for (i = 0; i <= 200; i++){
    points.push(center + vec2(
        r*Math.cos(i*2*Math.PI/200),
        r*Math.sin(i*2*Math.PI/200) 
    ));
}

Otherwise, if the 200 supplied in the start of the loop is a fraction of the 200 given in the calculation (r*Math.cos(i*2*Math.PI/200)), then only a fraction of the circle will be drawn. Also, without adding in the i to the calculation in the loop, the points are all the same value, resulting in a line.