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
need to apply an if/else statement to Tim Thumb script
Not sure how to work this. I essentially want to call a variety of image sizes based on which style
Local file browser with php
Halo..
So this is what i want to create. I have a folder that i share and it has many movies.
Login Functionality Working Different on IE
This is an odd one, I have a site which has an admin section. The admin pages unsurprisingly require
Code Review - SQL and Insertion Attacks (Warning: Not for Newbs)
Hey guys,
Its been a while, I know. Use to love coming here to answer peoples questions, but
Values disappear from my array :( HELP!
hey all, I have a lil mysql/php/apache script that queries a database
and pulls put 5 integers.undefined offset help
Hi All,
I kept getting undefined offset PHP notice for a simple for loop. For eg
$va = arr
php unable to sent email
Hi, guys, I try to send a email through php but unfortunately the mail unable to sent. Here is my co
WELCOME SCREEN
first of all let me tell you what does my script do,
it´s a very simple query to show a e
gather checkbox data from form into email
Hello all,
First, i'd like to thank everyone who responded to my previous posts regarding set
Simultaneous select/update/insert
Hi
How would I need to go about when 2 users update a single row simultaneous? And how would
