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

Combining Two Queries
I have two scripts that each work fine by themselves. One is a search script with a variable that de

Values disappear from my array :( HELP!
hey all, I have a lil mysql/php/apache script that queries a database
and pulls put 5 integers.

MySQL noob question
hi guys

I have a simple mysql table set up, along the lines of

Col 1 - Col 2 - Date_l

Dynamic Array using glob?
Is there an easier way to do this?

I am trying to get create a dyamic array based on files wi

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

Login script (probably a simple error)
dbConfig.php
Code: <?
// Replace the variable values below
// with your specific dat

tell csv import script to ignore blank rows?
Hi i have the below script but i get an error if a row is blank ie a return in the csv file at the e

Refining of search Criteria
Dear Friends

I need a help, I have a search page which of cars related, which has different s

Libraries in C++
Hi all,

I have two libraries. one is based targeted on linux platform and uses another li

PHP page is blank
Hi Everyone,

I have a site in which I am able to open the first PHP webpage in my browser but

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