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 to use php and sql to check if values match the ones in a table (for logins)
How would I code it that the script takes two variables that are passed to it (UserID and PIN), and
Count on multidimensional array
Hi, i got an array as below:
Array
(
=> Array
(
update 2 columns by doing inner 2-column query
Hi,
is something like this possible?
update contract_all set col1,col2 =
(
Need understanding of this bit of code
Code: <?php
// WHERE clause filters
$arrSQLFilters = array();
//
Bandwidth monitoring?
Hi guys,
I need a little information I have written a php app and I occurred to that I need
mysql_real_escape_string making variable equal nothing
i post a form and i post the variable:
Code: $var = $_POST[variable];then i echo $var its what i
Problems with strings containing
Hey all,
I have encountered something strange in a script. I am trying to write an XML heade
What am I missing here? Help!
Hello all!. I can't seem to get this working right. Well - it renders right, but something is goin
Syntax Help
I'm trying to make a form that edits a php file which contains config settings. I'm using strings t
How do I get the row number from from an sql table query
Hi all
I have a table that I query and it returns a number of rows.
mysql_num_rows($query)
