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

search function
HI guys,

if anyone could point us in the right direction of how to do this, or provide some t

Need Successful Return
Hello I am currently working a form here, and I have everything figured out except when I click the

Generate PDF
Hi guys,

I would like to know if there is a way to generate pdf when clicking on a link. In f

TemplatePower & AJAX
Hi all,



I'm currently implementing some AJAX features in my PHP-framework (which is b

xml element exists
Code: [Select]<?xml version="1.0"?>
<Addresses>
<

BSP Ext - tableView - Sort - NEWBIE
Hi,
I have been trying to get the sort to work. I have defined the column definitions by fillin

controlling/creating accounts with privileges
hi all,
i'm trying to figure out how i can create/control account with privileges, for instance a

Parse error: syntax error, unexpected T_ELSEIF in /home/......html/item.php on l
I do not know what is wrong with this. Hope some one can help. I do nto want to post the entire site

Scrolling news bar and MySQL
I am not sure if this is the correct forum to post this on. If not, I apologize. I am still pretty

mysq_num_rows
Hi,

I want to use:

Code: if(mysql_num_rows($ergebnis2)==2)
how can the value 2, be