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

subtract 1 from value entered in text field
Hi

How do I subtract 1 from the vaue entered into a text field?

Thanks

Include a php
Hello,

I'm trying to include a function that shows the recent searches.
Example I have <

How to add functionality to a simple php calender?
Hello everyone,

I have just finished creating a simple php calander. Can someone point

output_buffering so rewrite
I'm planning to rewrite some of my scripts so they don't have to use output buffering to accomplish

values in array being escaped
I would like to submit some values - back to the same form for checking before processing...

Procedure with variable number of columns
Hi, I have a procedure that looks like this:

PROCEDURE PROC(p_cursor OUT sys_refcurso

cURL and Sessions
Ohai.

So, I'm trying to cURL a bunch of things off of a page, and put them into a session. I'

PHP XML extraction text
I would like to extract an xml text and have that text directly echo(print) out on my web page. Her

help with image upload code
Hello,

right now this code I have resizes images and then places them into the uploads folder

urldecode question
How would I format this line of code properly?

<?php echo urldecode($_GET['Title']); ?

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