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

Problem related to Creation of PDF File?
Hi All,
I am facing a problem related to creation pdf file. when I am creating a pdf file of do

Form Help
Here is the form:

Line number On/Off | Expand/Contract<? include("../include/sess

Display certain image depending on time of year
Hi, I am new to these forums and would really appreciate some advice on a piece of coding I have don

Anti Spam Code Problems
Ok where do i start? Probably by telling you I have very little working knowledge of PHP and that I

returning data from an ssh2_exec()
here's what i got.


$conn = ssh2_connect($this->_host);
ssh2_auth_password($c

Problem with the Update command used with a sqldataadapter
I'm connected to a database on an SQL Server and I'm using a sqldataadapter, sqlconnection, sqldatas

captcha error
I have been trying to implement a captcha in php...

here is the code..
Code: (php) [Select

A href problem under php
Hello...

I tried to explain the issue in an earlier post.. but was not clear enough....

PHP & Images [Resize, Crop, Save]
Hey! Well I have a little dilema, hoping I could find some guidance.

I have a CMS and on the

Save data in input fields when they press "BACK BUTTON"
Hi, this is html form: And let's say they get a error "Please enter ur title must be more then