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

Insert data in Mysql and move to another page
I'm stuck with this simple problem. I need to insert data in Mysql and then hit submit and move to a

Problem executing bash script using shell_exec
Hi there,
I created a bash script file using following code to convert doc documents to pdf using

How do I give a developer access to a specific directory and nothing else?
I want to give a develop access to a specific directory and nothing else

I can give them an F

Echo-ing MySQL content and Keep Formatting?
I have data in my MySQL such as:

QuoteBlah blah

Blah blah

etc
but when i ech

PHP & Java
Hello,

can PHP code be used inside java code?

Code: [Select]<SCRIPT LANGUAGE=&q

Date Question
I'm using the TIMESTAMP() function within mysql to set the date/time for certain events. However, ho

Problem with HTTP Caching...?
Hi there, im trying to implement caching. But it doesn't always work.
I post it here because ther

Renaming a file that a user uploads to site?
My site allows for registered users to upload images to the site under their own gallery. Currently

MS Exchange 2007 integration with ECC 6.0
Hello Experts,
We have ECC 6.0 and MS Exchange 2007. We need to integrate ECC 6 and MS Excha

Add 5 to a variable when a button is clicked, and re-run a for loop
So I'm making a feedback sort of section on a website with MySQL and PHP, I've gotten the script to

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