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

Hits this week counter
I have a counter on my site that tracks hits, IP's, etc. into a mySQL database. It also includes the

Coefficient of a Restitution Hints
Hello. I was wondering if anyone can give me hints on how to write this program...

The coeffi

Redirect not working after making a POST/GET
Hi Everyone,

I am a novice in PHP. Here I have 2 pages, one page with a textbox and button an

How to submit a form to the same page?
I have a table containing information about books in my library and this table has the following col

problems with search form numerical "between" sending by php
I am trying to display the results of a search, on a sql database, on a web page. I set up html &quo

Calling strings from other php class
I have test1.php{
$string1;
$string2;
....
... //10 strings in this class <

Delete all files in folder except with certain name
I have a script that I want to delete all files in a folder (taken from a database) except for one n

get the country of visitor and display content based on that
Hello all,

I have seen that Google analytics can tell you where a visitor is coming from and

Warning: session_start() [function.session-start]: Cann.....
hi, can someone help me with this? I keep getting this error....

Warning: session_start() [fu

Log $_POST
How would i log submits on a form, by everyone? I want to then echo the number of submissions.

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