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 
53 
Other forums
Email logic not working
I would like to send an email using the php email() function then if it does execute i.e sends i wou
Creating web pages by php
Hello again,
I was just wondering us there a way to use a php script to create a new web page. I
TimeZoneOffset
Hello,
Please i need your help. I have a system that users can use to punch in and out. This
IP question
ive got 2 ip addresses both global from same user how would i detect if they are local to each other
Adding Outlook 2007 items via file upload
I am looking for a way to be able to attach an Outlook item (an email message) in an ASP.NET 3.5 app
Progress bar tracking file downloads
Hey guys, was wondering if there was a way to track how far a file has been downloaded. I know there
Count
Getting the same count everytime
Code:
$visitquery = mysql_query("SELECT COUNT(*) FR
Multiple arrays inside data
Hi,
Simple question. I have a column called "array" in my database, and inserted in
Slashes
Have a small problem and I'm not able to understand why I'm getting the results I'm getting... and i
Deleted Delivery but material wont return
We deleted a delivery but the material its still pending.
We made a reverse goods movemen
