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.

Did you know?Explore Trending and Topic pages for more stories like this.
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.
No comments posted yet

Your Answer:

Login to answer
213 Like 53 Dislike
Previous forums Next forums
Other forums

uploading video files into mysql in php
hi,
I have the video files which i have to upload into mysql db. along with creating thumbnails f

Online Event Ticket Sales
Has anyone wrote a script for online tickets sales?

I have been googling and found lots of th

Is there a way to override built in php functions without APD?
I am trying to use the
rename_function()
override_function()
options that are built into

need help in update query
hi
i have a dynamic form. i need help in how can i use update query when values from dynamic for

C problem struct and string
Hi guys,

This is my first post and I'm hoping the experts here can help me solve my problem.<

How to display objects in a row
I have 7 codes that i want to display in a row one next to another.
The first is {$ads->ad

Create comparison matrix?
I want to create a comparison script for forum software and was wondering is there any tutorial or b

returning data from an ssh2_exec()
here's what i got.


$conn = ssh2_connect($this->_host);
ssh2_auth_password($c

please hep to get values from a table row
can anyone tel me how I can select and get data from one row by pressing an Edit button in that row

Error when call dll from oracle
Hi all, please help me!

I have dll write C language, I want call it from oracle procedur

Sign up to write
Sign up now if you have flare of writing..
Login   |   Register
Follow Us
Indyaspeak @ Facebook Indyaspeak @ Twitter Indyaspeak @ Pinterest RSS



Play Free Quiz and Win Cash