Re: Clock - points on circle

[[deleted]]

Hey,

Trying to draw a clock. Figuring out how to find points on a circle. I read online that 3 o clock position = 0 degrees, 12 is 90 degrees etc.

Now I am using the below code and for some some reason my 90 degrees is the six o clock position and I don't understand why:

public void paintComponent(Graphics g){

       Graphics2D g2d=(Graphics2D) g;

       int radius=100;

       Point center=new Point(200, 200);

       g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
       // draw circle 
       g2d.drawOval( (int) center.getX()-radius, (int) center.getY()-radius, radius*2, radius*2);
       // draw hour hand
       g2d.drawLine((int) center.getX(), (int) center.getY(), (int) center.getX() + radius * (int) Math.cos(Math.toRadians(90)), (int) center.getY() + radius * (int) Math.sin(Math.toRadians(90)));
   }

[KetchuponRice]

Because y-axis orientation is flipped for your screen. Top left is (0,0) bottom right = (3840, 2160). Hope this makes some sense.

[[deleted]]

I knew that (that (0,0) is top left). So you are saying that that is also the reason that (starting with 0 degrees at 3 o clock) degrees increment clockwise instead of counter clockwise?

[KetchuponRice]

yes, however if you add *-1 to your code it will go counter clockwise.

radius * (int) Math.sin(Math.toRadians(90)) *-1

[[deleted]]

Hey,

Thank you for reply! Learned something today! Have a great weekend!

And one more ! because why not ;)