Floating Point Precision Loss


Posted on 16th Feb 2014 07:03 pm by admin

I'm writing a program to draw a three-dimensional cube (with a corner cut off) without using any 3D graphics APIs. The only API call I make is win32's SetPixel()

Everything is going great. I've drawn lines, faces, and even the entire cube. Then rotation came along.

Did you know?Explore Trending and Topic pages for more stories like this.
For some reason, when I rotate my cube, it begins to shrink. I became confused, then I realised something. Floating point numbers are truncated.

Here's some code that is fired everytime the user presses 'X' on the keyboard.

Code: p->setY( p->getY() * cos(5.0/180.0*PI) - p->getZ() * sin(5.0/180.0*PI)); p->setZ( p->getY() * sin(5.0/180.0*PI) + p->getZ() * cos(5.0/180.0*PI));

p is a Point object that I created. Here the Y value and the Z value of the Point are being set. The problem is everytime X is pressed, and this code is fired, a small amount of precision is lost. As a result, the cube shrinks.

I'm really completely stumped. I remember when studying assembler that floating point numbers can be truncated or rounded. I think rounding would solve my problem. Since 50% of the time the value would round up, and 50% of the time the value would round down.

Whereas with truncation values are always lost, and never gained.
No comments posted yet

Your Answer:

Login to answer
213 Like 53 Dislike
Previous forums Next forums
Other forums

noob question
i traying to do a php form with auto replay for both(me and the user who send me a mail),

a u

how to load a Sys file with system load and call images?
normally you need register the module as a service with CreateService, and start the service

Internal class functions don't seem to get executed.
Hi. Can someone please put me out of my misery on this. I don't write much PHP and this has me baffl

ob_ dynamic content
i was wondering about the potential to use ob to create a <div then remove it when the page

LIMIT $start, 10... how to pass last value queried into next page with GET??
Ok I know how to display the first or last 10 results of a query...

$result = mysql_query(&q

WM transfer order: confirm different batch than proposed by system
Hi folks,

following scenario: we have a full WM with mixed batch numbers allowed in stora

Display Database
I need to create a shopping cart. I found this code online: http://conceptlogic.com/jcart/
Unfort

pageination not working right... coping images over 4 pages
Code: <?php //This code will obtain the required page number from the $_GET array. Note that

include
Hi I have this way of licensing my PHP application, and I want to know if you guys can answer some q

ereg_replace in Wordpress
Heya - so I'm working on this site: http://world-of-smiles.theportlandco.com/new-patients

The

Sign up to write
Sign up now if you have flare of writing..
Login   |   Register
Follow Us
Indyaspeak @ Facebook Indyaspeak @ Twitter Indyaspeak @ Pinterest RSS



Play Free Quiz and Win Cash