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

weird problem
last time, i did post a topic concerning why my page sometime will load as blank page when using IE.

Something like an INI editor or a DelimitedText-Editor
Hi all,

Am very, very, very new to PHP and not sure if I should be posting this to a Javascri

Need help with an email blocker for a guessbook
I am new with php and here is a simple guessbook page but I am being hit with spam from a group of t

Query issues
I probably have this setup wrong well I know I do because nothing is showing up now. What I want is

Curl timeout breaks script
So im having difficulties with skipping timeout error in curl
my script calls different functions

Insert to MySQL inside foreach
Hey.
I am parsing some html, and putting inside an html db.
I need to create a randomized inte

Basic Question Regarding PHP Includes
Hi

Just starting out with PHP.

Working on a site that uses some basic includes, these

Mass activity scheduling
Hi experts,

Im facing some problems to deal with mass activity jobs.
When I run some

Sequre login with cookies.
I want to build secure login with cookies. I just want your ideas about this, your suggestions. What

How do I replace any number of character occurences with one occurrence?
How do I replace any number of character occurences with one occurrence?

Let's say I have:

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