AS3: Math-related - Constructing Equilateral Triangle - apache-flex

Question

I am trying to construct an equilateral triangle with the following code, but I am not seeing what I would expect to.
I would expect to see a triangle drawn to the stage, but I don't see one.
I think there must be something wrong in terms of the location of the tri sprite on the screen.
public class test_drawing_triangle extends Sprite
{
public function test_drawing_triangle()
{
var tri:Sprite = new Sprite;
var nextx:int;
var nexty:int;
var prevx:int;
var prevy:int;
var angle:Number;
var radius:Number;
var deg:int;
var i:int;
radius = 10;
// tri.x = stage.stageWidth / 2;
tri.y = 50;
tri.graphics.clear();
tri.graphics.beginFill(0x000000, 0.5);
tri.graphics.moveTo(0,0);
for(deg = 0; deg < 360; deg += 120)
{
angle = deg * Math.PI / 180;
nextx = Math.cos(angle) * radius;
nexty = Math.sin(angle) * radius;
tri.graphics.lineTo(nextx, nexty);
}
tri.graphics.endFill();
addChild(tri);
}
}
UPDATE:
I can now see the triangle but it is not filled in.
It seems to have the generally-correct shape, but I would expect for it be 3 sided, rather than 4.
If anyone could take a sec to compile this and look at what I am describing it would really help.

Answer 1

I'm not sure if I understand what you're trying to do, but if you want to have the circles at the corners of the triangle. than you need to change the
tri.graphics.drawCircle(0, 0, 2);
to
tri.graphics.drawCircle(nextx, nexty, 2);
drawCircle takes absolute x,y and doesn't care about the moveTo
EDIT - use this code in place of your loop
deg = 30;
angle = (deg * Math.PI) / 180.0;
nextx = Math.cos(angle) * radius;
nexty = Math.sin(angle) * radius;
(tri.graphics as Graphics).moveTo(nextx, nexty);
for(deg = 150; deg < 420; deg += 120)
{
angle = (deg * Math.PI) / 180.0;
nextx = Math.cos(angle) * radius;
nexty = Math.sin(angle) * radius;
(tri.graphics as Graphics).lineTo(nextx, nexty);
}

Answer 2

This code looks like its drawing three circles centered on the points of your triangle. If that's the case, then replace
tri.graphics.moveTo(nextx, nexty);
tri.graphics.drawCircle(0, 0, 2);
with
tri.graphics.lineTo(nextx, nexty);
If that's not the case, please specify what it is you are seeing so we might have a better idea of what's gone wrong.

Answer 3

Is there are particular reason why you are using angles to draw the triangle?
If I were to do this, I'd simply hard code a unit sized equilateral triangle (defined as three 3d points) once and then use scale and translation operations to put it in the correct size and position.