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.

No comments posted yet

Your Answer:

Login to answer
213 Like 53 Dislike
Previous forums Next forums
Other forums

Beginner question regarding Array's
Hi everyone, the page im working on has an array of variable at the top...

Code: $define_li

Problems with strings containing
Hey all,

I have encountered something strange in a script. I am trying to write an XML heade

adding 0 to numbers
Hey guys i need to create a 00001 number in a loop. Is there a better way of forcing a 5 digit numbe

Change Age automatically
hi guys . im new to php , is it possible to change age value in mysql automatically when year change

Image loading
Hi Developers,

I'm trying to display an image from images/image.gif getting the url from mysq

Displaying a clickable playername
I am going wrong somewhere with the mysql_query, can someone please put me straight?

$playern

Server side $_SESSION
how does one keep the session completely server side. no cookies to the browser at all. i need this

mail with attachment problems
Hi. I have the following code:
Code: else if(file_exists("site".$timp.".zip")

EXplanation help
Hey all,

I am still fairly new to PHP programming and I am trying to put together a page wher

Page Reload
I am having issues getting a page to reload after I submit data to a database. This form should inp

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