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
Help with Password Encoding/Decoding?
Trying to design a "change password" tool. On my signup code I'm using base64_encode, now
Problem with an browser game.
Hello,i just joined that great forum and i got php prob,its kinda freaky...anyway i got browser game
Appending GET data with form submition
Okay, what I'm trying to do is to use a form to append an already existing GET data string.
I
. and .. appearing instead of pictures
First of all, thanks very much for providing this forum. It is very much appreciated!
My son
Menu restriction
How can I restrict the individual menu that would appear when a user logs in so that all users are c
PEAR Email Attachment w/ $gpg
I have no issues with this code if I take out the attachement section and include the info in the em
Multiple server callbacks (NOT POSTBACKS)
Hello,
I have 2 different javascript client side functions that are on timers. When the timers elap
Change Sort Order to Display Newest File First
Hi Guys,
I have a page that sorts the contents (PDFs) of a directory and displays them on the
Automatic Webpage ??
I have a page www.mysite.com/test.php with a
<form>
<textarea name=&q
Wierd if else problem
Hi guys,
this probably aint wierd for you, but it seems like php is playin up to me. may b i
