polar co-ordinates : Java Glossary
home P words local find no local find frame, full screen Google search web for topic jump to footer translate with Babelfish by Roedy Green ©1996-2008 Canadian Mind Products
Go to : punctuation 0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z (all)
polar co-ordinates
Many geometric shapes, such as circles, spirals and polygons are easier to describe in polar co-ordinates, with an angle and radius instead of x,y. You have a central point and you measure the angle in radians counter clockwise from due east. You measure the radius as the distance from the centre.
Polar Cartesian Java Drawing
poral_coordinates cartesian_coordinates drawing_coordinates

You can convert polar co-ordinates to Cartesian x,y co-ordinates with:

// polar to Cartesian
double x = Math.cos( angleInRadians ) * radius;
double y = Math.sin( angleInRadians ) * radius;

// Cartesian to polar.
double radius = Math.sqrt( x * x + y * y );
double angleInRadians = Math.acos( x / radius );
To convert to drawing co-ordinates you must round to integers and invert the sign of y, since y grows down in Java rather than up as in mathematics.

CMP_homejump to top
CMP logo
feedback Please email your feedback for publication, errors, omissions, broken/redirected link reports
and suggestions to improve this page to Roedy Green : feedback email
made with CSS
HTML Checked!
ICRA ratings logo
mindprod.com IP:[65.110.21.43]
Your face IP:[38.103.63.18] The information on this page is for non-military use only.
You are visitor number 6,853. Military use includes use by defence contractors.
You can get a fresh copy of this page from: or possibly from your local J: drive (Java virtual drive/Mindprod website mirror)
http://mindprod.com/jgloss/polar.html J:\mindprod\jgloss\polar.html