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

unoconv doc convert to pdf code prob
PHP/5.3.1

Hi. I am trying to use this code to convert docs to .pdf utilizing unoconv. Howe

Anti Spam Code Problems
Ok where do i start? Probably by telling you I have very little working knowledge of PHP and that I

Is STL important?
I'm just starting programming and I've made it until the Standart Template Library. But the chapter

Variables and Include
Code: [Select]<?php

$header = $_COOKIE['mss']['header'];
$body = $_COOKIE['mss']['b

simple php table loop
Hi all,

I've the following code

<?php // Create category options

upload image name with extension using php
hi frds..

<input id="file1" type="file" name="file[]" &a

Printing issues with xMII 11.5
For some reason, we have one report (and only one) that is giving us fits when trying to print. The

Parse Error
Hi Guys,

I have a function in my class which returns a string link variable. The problem is i

BackButton Behaviour in AJAX
I have an ASPX Page AJAX Enabled!The page has a gridView and a DDL for filtering on it. The Gridview

Get last modified date of web page
Hai All,

In php how can i get last modified date of a give web page . I have tried to g