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

More pug propaganda.
http://www.youtube.com/watch?v=8Kkrmubsgf8

The commercial is definitely worth watching pug aw

Save User Inputs while javascript reloading!
hi..
i have written a PHP code in which i reload the page when user selects a value in dropdown..

PHP form help required
Hi all! Apologies in advance for having to message the forum for help. I know you must get a lot of

PHP and XML image gallery variable issue
I'm trying to display the large image on the same page as the thumbnails, to do that I'm passing a v

WHYISNT THIS MYSQL STATEMNT NOT WORKING? (php)
caps because its absolutely rediculous.
i dontunderstand why its not working. there is a column c

PHP Code To Change Font Color in Table Cell
I would appreciate help with the following snippet of my php code. I am just trying to change the f

Problem in OnClientClick and OnClick sync
Hi,Strange and irritating problem: I have below button declaration in markup of the aspx page:

Data storage spaces in varchar2
Trying to understand what's happening.
I am selecting a value from a table that is defined as c

Really need helps regarding Pagination with Sort
I need someone helps regarding pagination problem...i actually want to make my page limited to let s

Casting Decimals in Oracle
This code worked as a query in DB2, but I am not sure what the syntax is for casting decimals in Ora