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

whats wrong with my code please help!!!
this is the error


Warning: mysql_close(): supplied argument is not a valid MySQL-Link res

Embed Video Problem
Hey, thanks for looking!

File to be embedded:

Code: <playlist version="1&q

Open link with largest int string first
I have the following links i would like to open either all at once or one-by-one. How would i procee

Help with search.php
Hello All

I need the search engine on a site I am building at the moment to display the searc

how do i make a string??
hey guys,
can someone please tell me how to put data from the glob function into a string

Collecting AOL Search Terms
I am attempting to collect AOL search terms. I know the code is correct (it works for google, bing,

Calender Not Opening
The following code is not loading the javascript calender in another window. It's not doing anything

Adding Outlook 2007 items via file upload
I am looking for a way to be able to attach an Outlook item (an email message) in an ASP.NET 3.5 app

Required to login help
I'm trying to set up my site so users have to be logged into the forum to access the site.I've been

Fetching META TAGS through
Hello everybody
I want to fetch meta tags of a domain.
It will be done from following code of

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