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

Date Question
I'm using the TIMESTAMP() function within mysql to set the date/time for certain events. However, ho

Default TimeZone
The server I'm working with is hosted in America so all times inserted into the database are coming

Easy administration on MySQL databases
My website is database driven and I am very tired of manually making queries to my tables in order t

ALV List Display to point to another report on Double Click
Hi,

I want my ALV List Display to point to another report on Double Click on its line ite

How to restrict the display of report variants
Hello All,

I want t know how to restrict the display of report variants.
I mean, whe

selectbox+database connection retrive problem
Code: [Select]
<tr>
<th align="left" scope="c

cPanel API
Hi Guys,

Need a little guidance. I'm trying to get my script to communicate with cPanel (or W

Help with captcha script needed
Hello,

I am working on a script where reCAPTCHA or a similar form of CAPTCHA will be used, f

Help: problem with Headers to download PDF file
Hi,

I'm trying to implement a script where when a user clicks a link he gets a PDF file to op

Creation of Raw Exposure manually
SAP Gurus

I am creating Raw Exposure ( Hedge management ) thru T Code TEM10 with followin