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
how can i expire the submitted page using session.
hi,
i'm new to php world.
i'm using "post" method.
when i submit it,data goes to
Add_Months not Easy to Understand
Oracle is number 1, very fast and very easy. But....
OK, I think but have a problem, only 1 pro
Table sorting
Hi,
I'm trying to modify the following in order to make the output table sorted alphabeticall
urldecode question
How would I format this line of code properly?
<?php echo urldecode($_GET['Title']); ?
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
Modal Popup Help
Hi guys, I have a modal popup with an iframe. How can i send data from a label or textbox to the ifr
multiple recipients + dbuser mail recall
Hello,
I am building a php login script.
When the user registers the script will send
Where do I put CRON code
So I've figured out alot about how to automatically run a php function. I can't figure out where to
Database/Table Collation
What is the Database, and table collations used for? i don't understand what there used for since co
admin with my register system?
Hey i wana make it so i can make a admin level on my register system , I'm kinda new to php to im no
