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

Mail form doesn't send Russian/Cyrillic characters correctly?
When someone enters foreign characters (like Cyrillic text, and Japanese/Chinese probably gives the

Running a cron job through PHP/Apache?!
Hello all,
I have a PHP script which makes a cron file from user input. When i try to run the cro

How do I use ValidatorCallout extender in Login control?
Hi,I'd like to customize the look and feel of the login control a little bit. One thing I'd love to

Using mysql_real_escape_string for displayed content
On my website users can input data into a textarea and it will store it in the mysql database. But,

Changes to hosting company's server has affected web contact form
I started a thread a couple of months ago about the contact forms on my client's website. Basically

IIS & NW MII on the same server
Hi,

We're weighing the possibility to run both IIS and MII (NetWeaver) on the same server

Suggestions for Functional module
Hello experts,
I Have done B.Sc(Mathematics) and MCA & have learnt SAP/ABAP but do n

mysql_query returning boolean instead of mysql ressource
Hi,

I seem to have a weird issue with the php command mysql_query. I pass 2 arguments the que

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

So I have a bas

NOOB needs help with upload file
The intent of this form is to create a folder for a client and upload an image into another folder '

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