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

C++ Http request?
Code: string Response = "LOGIN_UNSUCCESSFUL"; System.Net.WebRequest request = Sy

PECL uploadprogress for php5.2
Hey, I just installed PHP5 via .htaccess on my 1and1 Shared Hosting Account.

How would I exac

Aris, Netweaver BPM, Visual composer and X'app
Dear Experts,

Whats the relationship between the following components: Aris, Netweaver BP

change text color with a jQuery code
Hihow can I change the text in a asp:TextBox to a different color when I start typing using jQuery?I

reating a background image
I am building a site in drupal and have a php form in it, due to certain annoyances with module buil

single page with referrer to show correct page
I have a simple website with a couple of different pages. I would like to be able to in a div tag w

Small problem with image resize script
Hi!

I am a little bit new to php and I have an issue installing an image resize script I down

Images outside webroot
Im hopeing someone can help me with this because i cant figure it out.I have setup an ASP.NET websit

Extract specific information from a PHP Multidimensional Array
Howdy! I've racked my brain over this for 24 hours now. I think it's time I asked for help. I'm lear

Dump with added_funcion cl_salv_table
Hi there, I'm having some troubles adding a self defined function to an ALV in fullscreen. The thing