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.

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.

Your Answer:

Login to answer

Other forums

FTP Programs
Here is a list of commonly suggested FTP Programs to use:

FileZilla
SmartFTP
CuteFTP

Multidimensional Array into an Html table, help!
Hello all, I am new to HTML/PHP so any help would be great.

I have a multidimensional array f

Any decent php formatter/beautifier/pretty printer?
Any decent php formatter/beautifier/pretty printer class/function?

I found the following whil

Help with PHP Calendar code...
Hello, I'm new to this forum and I'm glad I found it.
I wrote this code for a PHP calendar as an

smart reading from a text file
Hello there fellow coders, i was wondering if one of you wouldnt mind helping me with this problem i

Please help understand this code
I noticed the index page on my site was modified this morning and found this code inserted at the bo

Multiple Pages
Hi. Im very new to php. I'm trying to create a basic login/registration page.

So I have a bas

Using Windows message as a Handle
Hi,

I am writing one of my first multithreaded programs.

In one of the thread,

Checking if a process is running (problems including psapi.dll i think...)
Ok, so all I'm trying to do is check if a program is running...

I've found out that I nee

php require help needed
Ok i tried to use the search funtion but the word require is everywhere.

i'm really new to cr