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

MFC GUI Programming
I am working on a project right now that requires me to create a MFC Windows GUI. Basically it need

upload image name with extension using php
hi frds..

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

understanding functions and classes
Code: [Select]
class person {
var $name = "Jimmy Goe";

function get_nam

MySQL-PHP Query Results Help
Hello all. I'm hoping to be able to get some help in solving a problem with query/rowcount output. I

Form submissing with PHP and JQuery/Ajax
I have searched everywhere, but cannot find a solution for this... I have worked all day trying to g

php not working written for consumption of slots
1. Here is the function where i will be allowed to consume the slot booked by me.

2. Here i c

apart from cron
I need to run a php file every one hour. Is there any other solution apart from cron job?

Ajax Issues - Update Panel / Timer. Intellisense doesn't know about them
Type 'System.Web.UI.ScriptManager' does not have a public property named 'UpdatePanel'. That is wha

Saas with SAP R/3
hi experts,

Is SaaS offer available in SAP? for SAP R/3? from where i can get the info a

Display thumbnails as square while retaining aspect ratio
I am trying to figure out a way to make an image display as a square, for example 80x80 pixels, when