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

'grab_files', multiple extension?
hey guys,

can anyone suggest a way to make to following line of code look for files with more

Filtering Tables
Hello Thanks for any help any one can give Im very new to PHP..

I need to pull data for clien

Required to login help
I'm trying to set up my site so users have to be logged into the forum to access the site.I've been

How to Handle more than one submit button in single form?
Hi
I have one PHP file which contains one Form. In this form there are two Submit type Buttons

Inserting a variable in a link
I have this code that I want to insert for my own variable but I have no idea how. This is what I wa

SWF image using php?
Hello once again.

My latest en devour requires me to produce an image of a static .swf that i

PHP SUBMIT
Code: <input name="doLogin" type="image" src="images/loginsubmit.jpg

constructor ?
i have written this program and made 3 constructors in the class and i want to call them in the main

Adding to an Int row in db
Hi, i have a database which houses all of the users of my site. One of the columns is for points whi

Send inserts to mysql thru port 80
Hi!

I have an application that must do some inserts in a mysql db. This db is behind a firewa